- Email: [email protected]
Value of platelet sensitivity to antiaggregatory prostaglandins (PGI2, PGE1, PGD2) in 50 patients with myocardial infarction at young age
Prostaglandinsand Medicine 7: 125-132,1981
VALUE GLANDINS
OF
PLATELET
PGE1,
(PGIp DIAL
H. SINZINGER,
SENSITIVITY PGD$
INFARCTION
TO ANTIAGGREGATORY IN
50 PATIENTS
AT
YOUNG
J. KALIMAN, K. WIDHALM,
WITH
PROSTAMYOCAR-
AGE
0. PACHINGER
and
P. PROBST *) (Atherosclerosis Res. Group at the Dept. of Medical Physiology, Atherosclerosis and Thrombosis Res. Comm. of the Austrian Academy of Sciences, Dept. of Nuclear Medicine, Dept. of Cardiology and Pediatrics, University of Vienna, Austria) ABSTRACT Based upon earlier findings of our group that not only the synthesis of antiaggregatory prostaglandins by the vessel. wall is altered in atherosclerotic vascular tissue of patients, but also the sensitivity of their platelets to these prostaglandins is changed, we examined a well defined group of 50 patients with myocardial infarction before the age of 40 years. In all patients the coronary heart disease was verified by angiography. The sensitivity of the platelets was examined in relation to the smoking habit, the type and presence of hyperlipoproteinemia, one, two and three vessel disease and familial history. Except for hyperlipoproteinemia and smoking, all the patients were free of any additional risk factor. It is demonstrated that the platelet sensitivity to the antiaggregatory prostaglandins is significantly diminished in hyperlipoproteinemics in comparison to a control group. INTRODUCTION Prostacyclin formation by atherosclerotic arteries in both human (1) and experimental animals (2) is statistically significantly diminished. This alteration, which seems to oc-
*) The expert help of our technician Andrea Gall during this study is kindly acknowledged ! 125
cur within weeks or months (3) has been believed in recent years to play a key role in the disturbance of hemostatic balance (4) in atherosclerosis and related diseases. The sensitivity of platelets to the antiaggregatory prostaglandins (5), however, has been almost neglected, though a change can occur within a few seconds (6), and the amount of the alteration is sometimes very marked (7). Continuing studies of our group in which we found a decrease in platelet sensitivity in hyperlipoproteinemias and in diabetics (8), we investigated a well defined group of young patients suffering from myocardial infarction before the age of 40 years. PATIENTS, MATERIAL AND METHODS We studied 50 patients (3 females, 47 males) with myocardial infarction at an age of less than 40 years. The investigation was performed 6 - 36 months after the event. In all the patients the existence of coronary heart disease was verified by means of coronary angiography. None of the patients had hypertension or diabetes mellitus. 2 were obese. The smoking behaviour before and after the myocardial infarction is given on the tables. Except for R-blockers the patients took only digitalis and some of them vasodilating agents (nitro). Blood samples were withdrawn in the mornirig after an overnight fast of at least 12 hours for platelet sensitivity testing and serum lipid and lipoprotein profile examination. For platelet sensitivity testing blood was taken from a cubital vein without occlusion using 3,8% sodium citrate (1:9) as anticoagulant. The anticoagulated blood was sedimented at room temperature (22OC) for IO minutes and then centrifuged for 5 minutes at 150 g to obtain platelet rich plasma (PRP), which was carefully removed. The remaining material was centrifuged again for 15 minutes at 1500 g to obtain platelet poor plasma (PPP). PPP was adjusted with PRP to give a final platelet count of 250 x 103/~1. Aggregation was induced with 1 PM/~ ADP in 600 ~1 PRP samples, one minute after addition of 100~1 solution containing various concentrations of the antiaggregatory prostaglandins (PGEl, PGD2 and PG12 - kindly supplied by Dr. John E. Pike, The Upjohn Company, Kalamazoo, Michigan, USA and Prof. Dr. C. A. Gandolfi, Farmitalia Carlo Erba, Milano, Italy). The ADP-induced aggregation was inhibited by at least 3 concentration of each of the antiaggregatory prostaglandins. From a curve the ID50 (concentration necessary, to reduce the aggregation response by half) was calculated and verified by addition of this amount of the prostaglandin to the PRP. The sensitivity of the platelets is given in ng prostaglandin/ml (ID50). Determination of serum total cholesterol and triglycerides was done by means of full enzymatic methods. Quality control for cholesterol using lipid standard sera (Precilip; Boehringer Mannheim, GFR) resulted in a coefficient of variation between 2 and 3%. External quality control was done by the WHO Lipid Reference Laboratory, Prague (coefficient of variation below 2 %). Estimation of lipoproteins was performed according to the US-National Institutes of Health Methods Lipid Research Clinics Program). 126
The values for platelet sensitivity were correlated with the the coronary angiographic fintype of hyperlipoproteinemia, dings, the smoking behaviour before myocardial infarction and the use of B-blockers at the time of the study. 30 patients (healthy outpatients, age treated in the same way and served as had taken any medication for at least vestigation. All were non-smokers and
and sex matched) were controls. None of them 14 days before the inhad a normal body weight.
RESULTS The sensitivity of the platelets to Prostacyclin (PGI2) in the control population was I,17 ng. In the patients with myocardial infarction, but normal serum lipids and normal lipoprotein profile the value was I,3 ng (table 1). In hyperlipidemic patients with myocardial infarction, the platelet sensitivity to exogenous, synthetic PGI2 was lower (i.e. higher amounts of PGI2 were necessary, to suppress the ADP-induced aggregation), depending on the type of hyperlipoproteinemia (HLP). The lowest sensitivity was found in type IIa according to Fredrickson (table 1).
TABLE 1 PGD2
PGEl
number
Patients
PGI2
MI (NL)
I,3 + 0,l
40,6 t 2,8
18,2 + I,5
20
MI + IIa
I,7 2 0,2
46,2 + 2,2*)
27,2 2 3,2*)
10
MI + IIb
I,5 + 0,2
36,4
+ 4,5
23,3 + 2,7
10
MI + IV
I,6 + 0,2
40,9
+ 4,7
26,4 2 2,3
10
HLP
I,6 2 o,l*)
41,9
_f I,9
25,6 z 111 *)
30
controls
I,2 + 0,l
35,2
z 2,0
17,8 + 0,5
30
x t SEM, *) p (O,Ol **) p co,05
;:;;e;;;,;~~;;;iy;;y
(ID5o ) in ng/ml in patients with myocar-
normolipemics (NL) and with the different types of HLP. Only in type IIa-HLP for PGD (p
127
ng PGE,
.30
0 :
‘. ..
.:.
..
‘. -.
:
._ ‘.
:
8
/.o.\v . . .. . ,...
‘.
,’
‘. ‘&
25
:
a-_,_
:’
6
/
\
/
/
//
.p/’
.. .
\
\
1 vessel
d.
2 vessel
d.
3 vessel
d.
\
---8 -0
/ /
b’
/
/
?? -0
\
\
T i
/ 0’ 1 t NL
ng
I
I
I
IIa
IIb
I
I
IV
I
PGD2 3
FIGURE
4. -___ _:’ .. ,I’ .. .’ (,.’ .,’
.o...._ _,.’ .<.. :’
45
._
?I
:.
0-.'
.-..._.6”
co
tota
‘\
\\\ /A //
/
0
\
1’
40
/
\
\
/
\
/
tL
35
\
/
30
,
??
NL
IIa
/ 8
/ 4\ / \\ / /I \ / ‘2, \
IIb
2 + SEM 128
IV
/
total
T
0
I
co
Comparing the values for all the patients with HLP together with the controls on the one hand and those with myocardial infarction and normal lipids on the other hand, it can be seen, that HLP might be the cause for the significant alteration in the sensitivity (table 1). Analysing the data in table 1, the infarction alone seems to have no effect. From the methodological point of view, it seems to us noteworthy, that the primary response of the platelets to ADP was more active in HLP-patients and normolipemics with myocardial infarction. However, the responses were not statistically significant (table 2) TABLE 2 alpha
A Tmax.
controls
72,2 + I,5
51,8 + I,9
MI (NL)
75,l + 2,5
53,4 + 3,8
HLP
78,5 + 1,5
53,9 + 3,3
x t SEM; n.s. Analysing the platelet sensitivity according to the number of involved coronary vessels, it can be seen, that for all. the prostaglandins (PG12 - figure 1; PGEl - figure 2; PGD2 - figure 3) the lowest sensitivity can be found in the case of one vessel disease, whereas in three vessel disease the sensitivity was always the highest. With the exception of prostaglandin D2 the pathological alterations were much more pronounced in type IIa than type IV, followed by type IIb patients. As in some subgroups the total number of patients decreased to 4, we did not calculate any statistics for figures 3 - 5 (all data were given as a mean value). FIGURE
1
ng PGI I,75
vessel dis I,50 vessel
I,25 I
dis.
T v.d.
1
I
,oo
0,75
r_
t
0r50 NL
IIa
IIb
x + SEM -_
IV
total
CO
srlly LX platelet sensitivity with respect to smoking behaviour, we found that the data for all the prostaglandins used were not different between the group of continuing smokers and the patients who stopped smoking after the event (table 3). However, the sensitivity of non-smokers u-
L-ulaLy
TABLE 3 PGI2
PGD2
PGEl
smokers
I,44
43,3
23,2
smoker bef.MI
I,45
40,8
22,8
non-smokers
1,22*'
44,5
1.7,3*'
x;
“)
p-co,01
sing PGI and PGE., was significantly different (p&0,01), whereas $his was not the case for PGD2. An analysis of smoking behaviour using the subgroups listed above as well as a correlation with the R-blocker medication did not show any differences. DISCUSSION Whereas the vascular prostacyclin formation has been analyzed in human (1,9,10) and experimental animal models (2, 11,12), the roles of the other antiaggregatory prostaglandins (E.,and D2) have been neglected. A similar story occured with the platelets (13-16), where prostacyclin attracted the main interest of the researchers in this field. In general, though the platelets are circulating in a vessel in close vicinity to the vascular endothelial cells, the role of interaction between the produced amounts of antiaggregatory prostaglandins and the sensitivity of the platelets to these substances has been underestimated. In an earlier communication having studied only a small population with advanced atherosclerosis, i.e. coronary heart disease and peripheral vascular disease (16) we found, that the platelet sensitivity to PGI2 was diminished, but not to a statistically significant degree. Only the patients who also had diabetes mellitus exhibited a significant difference. Having now analysed a larger number of patients with peripheral vascular disease without any other risk factor we have observed that the response to PG12 by the platelets was really significantly different. These data point out that severe atherosclerosis, at least in hums.ns is associated with an alteration in the platelet response to PGI2. In a young patient group with recently discovered hyperlipoproteinemia we also found a significant decrease of platelet sensitivity (8). This fact, as well as the unknown influences of many risk factors on the platelet sensitivity to antiaggregatory prostaglandins stimulated us to look at a well defined patient group suffering from myocardial infarction below the age of 40 years, in which a high percentage of 60% had different types of hyperlipoproteinemias. The disadvantage of this group is that when analysing some influencing 130
factors, the number of the patients be relatively low (4-5).
in some subgroups may
Surprisingly, the patients with and without hyperlipoproteinemia have the lowest platelet sensitivity in case of single vessel disease and the highest in three vessel disease. We described very recently (18) using the same patient group a relation between the type and intensity of hyperlipoproteinemia. A strong correlation between HLP and invo1vemen.t of more than one of the heart vessels and an influence of HLP alone on platelet sensitivity was observed too. It seems to us# that not only HLP but also the involvement of the vessels (number ? localization ? extent ?) might play a role in perpetuation of the atherosclerotic process in influencing the platelet vessel wall interaction. Other factors well known to enhance the risk of coronary heart disease such as smoking also exert a bad influence. Surprisingly, the behaviour was not different between patients still smoking and those who stopped smoking after the event. In addition, it seems to us that the more the number of risk factors, the lower is the platelet sensitivity to antiaggregatory prostaglandins. However, this must be accepted very cautiously due to the small number of patients analyzed. Our findings of a parallelism in the sensitivity between PGI2 and PGEl support the hypothesis that both these prostaglandins share the same receptor on the platelet surface. An other important fact, that essential fatty acid deficiency might reduce the sensitivity has not been examined in this our study. Summarizing,our data suggest that platelet sensitivity not only to prostacyclin, but also to PGEl and PGD seems to play a key role in maintaining the hemostatic i? alance. Analysing the risk factors presented in this study, it seems to us that not only the synthesis of PGs but also the sensitivity of cells to them and their degradation might be all key events for initiation and progression of human atherosclerosis and should be studied further.
REFERENCES 1 .
Sinzinger,H.,Feigl,W.,Silberbauer,K. Prostacyclin generation human atherosclerotic arteries. Lancet 1980, ii, 469.
by
2. Dembinskakiec,A.,Gryglewska,T.,Zmuda,A.,Gryglewski,R.J. The generation of prostacyclin by arteries and by the coronary vascular bed is reduced in experimental atherosclerosis in rabbits. Atherosclerosis 1977, 14, 1025. 3. Sinzinger,H., Silberbauer,K.,Winter,M.,Clopath,P. Effects of experimentally induced atherosclerosis on prostacyclin generation in arteries of miniature swine. Artery 1980, 5, 448. 4. Moncada,S.,Higgs,E.A.,Vane,J.R. Human arterial and venous tissue generate prostacyclin (prostaglandin x1, a potent inhibitor of platelet aggregation. Lancet 1977, i, 18.
171
5. Moncada,S .,Whittle,B.J.R. Relative potency of prostacyclin, prostaglandin E., and D as inhibitors of platelet aggregation in several species. J. Pl?ysiol. 1977, 273, 2. 6. Burghuber,O.,Sinzinger,H.,Silberbauer,K.,Leithner,Ch.,Haber,P. Decreased platelet sensitivity to prostacyclin after jogging and squash. Prostaglandins and Medicine 1981 (in press). 7. Sinzinger,H.,Kaliman,J. Prostacyclin sensitivity of human platelets in coronary heart disease with and without diabetes mell.itus (submitted for publication). 8. Sinzinger,H.,Widhalm,K .,Gall,A. Decreased sensitivity of human platelets to antiaggregatory prostaglandins (PGI PGEl, PGD ) in patients with different types of hyperlipopro 4'. einemia (sul& mitted for publication). 9. Silberbauer,K.,Schernthaner,G.,Sinzinger,H.,Piza-Katzer,H.,Winter,M. Decreased vascular prostacyclin in juvenile-onset diabetes. The New Engl. J. Med. 1979, 400, 366. 10. D'Angelo,V.,Villa,S.,Mysliwiec,M.,Donati,~.B.,DeGaetano,G. Defective fibrinolytic and prostacyclin-like activity in human atheromatous plaques. Thromb. Haemost. 1978, 39, 535. Effect of 11. Silberbauer,K.,Clopath,P.,Sinzinger,H.,Schernthaner,G. experimentally induced diabetes on swine vascular prostacyclin (PG12-)synthesis. Artery 1980, 8, 30. 12. Sinzinger,H.,Clopath,P.,Silberbauer,K. minipig aortic prostacyclin formation 1980, 8, 23.
The effect of ballooning - a time course. Artery
on
13. Siegl,A.M.,Smith,J.B.,Silver,M.J.,Nicolaou,K.C.,Ahern,D. Selective binding site for 3H-prostacyclin on platelets. J. Clin. Invest. 1979, 63, 215. 14. Garcia-Conde,J.,Amado,J.A.,Merino,J.,Benet,I. Prostaglandins and platelet function in diabetes. Thromb. Haemost. 1979, 42, 798. 15.
Klein,K.,Kaliman,J.,Sinzinger,H.,Silberbauer,K. Plattchensensitivitat fiir Prostacyclin bei diabetischen und nicht-diabetischen Patienten mit atherosklerotischen GefaBveranderungen - ein MaB fiir die Prostacyclinrezeptoren der Plattchenmembran ? VASA 1980, 9, 123.
16. Klein,K .,Sinzinger,H., Silberbauer,J.Kaliman. Enhanced prostacyclin formation but normal platelet sensitivity in women taking oral contraceptives. Pharm. Res. Comm. 1980, 4, 325. Decreased platelet sensitivity to the an17. Kaliman,J.,Sinzinger,H. tiaggregatory prostaglandins in patients with peripheral vascular disease. (submitted for publication). 18. Kaliman,J.,Sinzinger,H.,Widhalm,K.,Probst,P.,Pachinger,O. Serum lipoproteins and platelet function in patients with myocardial infarction below the age of 40. Proceedings of the Meeting "Myocardial infarction at young age", Bad Krozingen, January 1981, H. Roskam (ed.).
132
VALUE GLANDINS
OF
PLATELET
PGE1,
(PGIp DIAL
H. SINZINGER,
SENSITIVITY PGD$
INFARCTION
TO ANTIAGGREGATORY IN
50 PATIENTS
AT
YOUNG
J. KALIMAN, K. WIDHALM,
WITH
PROSTAMYOCAR-
AGE
0. PACHINGER
and
P. PROBST *) (Atherosclerosis Res. Group at the Dept. of Medical Physiology, Atherosclerosis and Thrombosis Res. Comm. of the Austrian Academy of Sciences, Dept. of Nuclear Medicine, Dept. of Cardiology and Pediatrics, University of Vienna, Austria) ABSTRACT Based upon earlier findings of our group that not only the synthesis of antiaggregatory prostaglandins by the vessel. wall is altered in atherosclerotic vascular tissue of patients, but also the sensitivity of their platelets to these prostaglandins is changed, we examined a well defined group of 50 patients with myocardial infarction before the age of 40 years. In all patients the coronary heart disease was verified by angiography. The sensitivity of the platelets was examined in relation to the smoking habit, the type and presence of hyperlipoproteinemia, one, two and three vessel disease and familial history. Except for hyperlipoproteinemia and smoking, all the patients were free of any additional risk factor. It is demonstrated that the platelet sensitivity to the antiaggregatory prostaglandins is significantly diminished in hyperlipoproteinemics in comparison to a control group. INTRODUCTION Prostacyclin formation by atherosclerotic arteries in both human (1) and experimental animals (2) is statistically significantly diminished. This alteration, which seems to oc-
*) The expert help of our technician Andrea Gall during this study is kindly acknowledged ! 125
cur within weeks or months (3) has been believed in recent years to play a key role in the disturbance of hemostatic balance (4) in atherosclerosis and related diseases. The sensitivity of platelets to the antiaggregatory prostaglandins (5), however, has been almost neglected, though a change can occur within a few seconds (6), and the amount of the alteration is sometimes very marked (7). Continuing studies of our group in which we found a decrease in platelet sensitivity in hyperlipoproteinemias and in diabetics (8), we investigated a well defined group of young patients suffering from myocardial infarction before the age of 40 years. PATIENTS, MATERIAL AND METHODS We studied 50 patients (3 females, 47 males) with myocardial infarction at an age of less than 40 years. The investigation was performed 6 - 36 months after the event. In all the patients the existence of coronary heart disease was verified by means of coronary angiography. None of the patients had hypertension or diabetes mellitus. 2 were obese. The smoking behaviour before and after the myocardial infarction is given on the tables. Except for R-blockers the patients took only digitalis and some of them vasodilating agents (nitro). Blood samples were withdrawn in the mornirig after an overnight fast of at least 12 hours for platelet sensitivity testing and serum lipid and lipoprotein profile examination. For platelet sensitivity testing blood was taken from a cubital vein without occlusion using 3,8% sodium citrate (1:9) as anticoagulant. The anticoagulated blood was sedimented at room temperature (22OC) for IO minutes and then centrifuged for 5 minutes at 150 g to obtain platelet rich plasma (PRP), which was carefully removed. The remaining material was centrifuged again for 15 minutes at 1500 g to obtain platelet poor plasma (PPP). PPP was adjusted with PRP to give a final platelet count of 250 x 103/~1. Aggregation was induced with 1 PM/~ ADP in 600 ~1 PRP samples, one minute after addition of 100~1 solution containing various concentrations of the antiaggregatory prostaglandins (PGEl, PGD2 and PG12 - kindly supplied by Dr. John E. Pike, The Upjohn Company, Kalamazoo, Michigan, USA and Prof. Dr. C. A. Gandolfi, Farmitalia Carlo Erba, Milano, Italy). The ADP-induced aggregation was inhibited by at least 3 concentration of each of the antiaggregatory prostaglandins. From a curve the ID50 (concentration necessary, to reduce the aggregation response by half) was calculated and verified by addition of this amount of the prostaglandin to the PRP. The sensitivity of the platelets is given in ng prostaglandin/ml (ID50). Determination of serum total cholesterol and triglycerides was done by means of full enzymatic methods. Quality control for cholesterol using lipid standard sera (Precilip; Boehringer Mannheim, GFR) resulted in a coefficient of variation between 2 and 3%. External quality control was done by the WHO Lipid Reference Laboratory, Prague (coefficient of variation below 2 %). Estimation of lipoproteins was performed according to the US-National Institutes of Health Methods Lipid Research Clinics Program). 126
The values for platelet sensitivity were correlated with the the coronary angiographic fintype of hyperlipoproteinemia, dings, the smoking behaviour before myocardial infarction and the use of B-blockers at the time of the study. 30 patients (healthy outpatients, age treated in the same way and served as had taken any medication for at least vestigation. All were non-smokers and
and sex matched) were controls. None of them 14 days before the inhad a normal body weight.
RESULTS The sensitivity of the platelets to Prostacyclin (PGI2) in the control population was I,17 ng. In the patients with myocardial infarction, but normal serum lipids and normal lipoprotein profile the value was I,3 ng (table 1). In hyperlipidemic patients with myocardial infarction, the platelet sensitivity to exogenous, synthetic PGI2 was lower (i.e. higher amounts of PGI2 were necessary, to suppress the ADP-induced aggregation), depending on the type of hyperlipoproteinemia (HLP). The lowest sensitivity was found in type IIa according to Fredrickson (table 1).
TABLE 1 PGD2
PGEl
number
Patients
PGI2
MI (NL)
I,3 + 0,l
40,6 t 2,8
18,2 + I,5
20
MI + IIa
I,7 2 0,2
46,2 + 2,2*)
27,2 2 3,2*)
10
MI + IIb
I,5 + 0,2
36,4
+ 4,5
23,3 + 2,7
10
MI + IV
I,6 + 0,2
40,9
+ 4,7
26,4 2 2,3
10
HLP
I,6 2 o,l*)
41,9
_f I,9
25,6 z 111 *)
30
controls
I,2 + 0,l
35,2
z 2,0
17,8 + 0,5
30
x t SEM, *) p (O,Ol **) p co,05
;:;;e;;;,;~~;;;iy;;y
(ID5o ) in ng/ml in patients with myocar-
normolipemics (NL) and with the different types of HLP. Only in type IIa-HLP for PGD (p
127
ng PGE,
.30
0 :
‘. ..
.:.
..
‘. -.
:
._ ‘.
:
8
/.o.\v . . .. . ,...
‘.
,’
‘. ‘&
25
:
a-_,_
:’
6
/
\
/
/
//
.p/’
.. .
\
\
1 vessel
d.
2 vessel
d.
3 vessel
d.
\
---8 -0
/ /
b’
/
/
?? -0
\
\
T i
/ 0’ 1 t NL
ng
I
I
I
IIa
IIb
I
I
IV
I
PGD2 3
FIGURE
4. -___ _:’ .. ,I’ .. .’ (,.’ .,’
.o...._ _,.’ .<.. :’
45
._
?I
:.
0-.'
.-..._.6”
co
tota
‘\
\\\ /A //
/
0
\
1’
40
/
\
\
/
\
/
tL
35
\
/
30
,
??
NL
IIa
/ 8
/ 4\ / \\ / /I \ / ‘2, \
IIb
2 + SEM 128
IV
/
total
T
0
I
co
Comparing the values for all the patients with HLP together with the controls on the one hand and those with myocardial infarction and normal lipids on the other hand, it can be seen, that HLP might be the cause for the significant alteration in the sensitivity (table 1). Analysing the data in table 1, the infarction alone seems to have no effect. From the methodological point of view, it seems to us noteworthy, that the primary response of the platelets to ADP was more active in HLP-patients and normolipemics with myocardial infarction. However, the responses were not statistically significant (table 2) TABLE 2 alpha
A Tmax.
controls
72,2 + I,5
51,8 + I,9
MI (NL)
75,l + 2,5
53,4 + 3,8
HLP
78,5 + 1,5
53,9 + 3,3
x t SEM; n.s. Analysing the platelet sensitivity according to the number of involved coronary vessels, it can be seen, that for all. the prostaglandins (PG12 - figure 1; PGEl - figure 2; PGD2 - figure 3) the lowest sensitivity can be found in the case of one vessel disease, whereas in three vessel disease the sensitivity was always the highest. With the exception of prostaglandin D2 the pathological alterations were much more pronounced in type IIa than type IV, followed by type IIb patients. As in some subgroups the total number of patients decreased to 4, we did not calculate any statistics for figures 3 - 5 (all data were given as a mean value). FIGURE
1
ng PGI I,75
vessel dis I,50 vessel
I,25 I
dis.
T v.d.
1
I
,oo
0,75
r_
t
0r50 NL
IIa
IIb
x + SEM -_
IV
total
CO
srlly LX platelet sensitivity with respect to smoking behaviour, we found that the data for all the prostaglandins used were not different between the group of continuing smokers and the patients who stopped smoking after the event (table 3). However, the sensitivity of non-smokers u-
L-ulaLy
TABLE 3 PGI2
PGD2
PGEl
smokers
I,44
43,3
23,2
smoker bef.MI
I,45
40,8
22,8
non-smokers
1,22*'
44,5
1.7,3*'
x;
“)
p-co,01
sing PGI and PGE., was significantly different (p&0,01), whereas $his was not the case for PGD2. An analysis of smoking behaviour using the subgroups listed above as well as a correlation with the R-blocker medication did not show any differences. DISCUSSION Whereas the vascular prostacyclin formation has been analyzed in human (1,9,10) and experimental animal models (2, 11,12), the roles of the other antiaggregatory prostaglandins (E.,and D2) have been neglected. A similar story occured with the platelets (13-16), where prostacyclin attracted the main interest of the researchers in this field. In general, though the platelets are circulating in a vessel in close vicinity to the vascular endothelial cells, the role of interaction between the produced amounts of antiaggregatory prostaglandins and the sensitivity of the platelets to these substances has been underestimated. In an earlier communication having studied only a small population with advanced atherosclerosis, i.e. coronary heart disease and peripheral vascular disease (16) we found, that the platelet sensitivity to PGI2 was diminished, but not to a statistically significant degree. Only the patients who also had diabetes mellitus exhibited a significant difference. Having now analysed a larger number of patients with peripheral vascular disease without any other risk factor we have observed that the response to PG12 by the platelets was really significantly different. These data point out that severe atherosclerosis, at least in hums.ns is associated with an alteration in the platelet response to PGI2. In a young patient group with recently discovered hyperlipoproteinemia we also found a significant decrease of platelet sensitivity (8). This fact, as well as the unknown influences of many risk factors on the platelet sensitivity to antiaggregatory prostaglandins stimulated us to look at a well defined patient group suffering from myocardial infarction below the age of 40 years, in which a high percentage of 60% had different types of hyperlipoproteinemias. The disadvantage of this group is that when analysing some influencing 130
factors, the number of the patients be relatively low (4-5).
in some subgroups may
Surprisingly, the patients with and without hyperlipoproteinemia have the lowest platelet sensitivity in case of single vessel disease and the highest in three vessel disease. We described very recently (18) using the same patient group a relation between the type and intensity of hyperlipoproteinemia. A strong correlation between HLP and invo1vemen.t of more than one of the heart vessels and an influence of HLP alone on platelet sensitivity was observed too. It seems to us# that not only HLP but also the involvement of the vessels (number ? localization ? extent ?) might play a role in perpetuation of the atherosclerotic process in influencing the platelet vessel wall interaction. Other factors well known to enhance the risk of coronary heart disease such as smoking also exert a bad influence. Surprisingly, the behaviour was not different between patients still smoking and those who stopped smoking after the event. In addition, it seems to us that the more the number of risk factors, the lower is the platelet sensitivity to antiaggregatory prostaglandins. However, this must be accepted very cautiously due to the small number of patients analyzed. Our findings of a parallelism in the sensitivity between PGI2 and PGEl support the hypothesis that both these prostaglandins share the same receptor on the platelet surface. An other important fact, that essential fatty acid deficiency might reduce the sensitivity has not been examined in this our study. Summarizing,our data suggest that platelet sensitivity not only to prostacyclin, but also to PGEl and PGD seems to play a key role in maintaining the hemostatic i? alance. Analysing the risk factors presented in this study, it seems to us that not only the synthesis of PGs but also the sensitivity of cells to them and their degradation might be all key events for initiation and progression of human atherosclerosis and should be studied further.
REFERENCES 1 .
Sinzinger,H.,Feigl,W.,Silberbauer,K. Prostacyclin generation human atherosclerotic arteries. Lancet 1980, ii, 469.
by
2. Dembinskakiec,A.,Gryglewska,T.,Zmuda,A.,Gryglewski,R.J. The generation of prostacyclin by arteries and by the coronary vascular bed is reduced in experimental atherosclerosis in rabbits. Atherosclerosis 1977, 14, 1025. 3. Sinzinger,H., Silberbauer,K.,Winter,M.,Clopath,P. Effects of experimentally induced atherosclerosis on prostacyclin generation in arteries of miniature swine. Artery 1980, 5, 448. 4. Moncada,S.,Higgs,E.A.,Vane,J.R. Human arterial and venous tissue generate prostacyclin (prostaglandin x1, a potent inhibitor of platelet aggregation. Lancet 1977, i, 18.
171
5. Moncada,S .,Whittle,B.J.R. Relative potency of prostacyclin, prostaglandin E., and D as inhibitors of platelet aggregation in several species. J. Pl?ysiol. 1977, 273, 2. 6. Burghuber,O.,Sinzinger,H.,Silberbauer,K.,Leithner,Ch.,Haber,P. Decreased platelet sensitivity to prostacyclin after jogging and squash. Prostaglandins and Medicine 1981 (in press). 7. Sinzinger,H.,Kaliman,J. Prostacyclin sensitivity of human platelets in coronary heart disease with and without diabetes mell.itus (submitted for publication). 8. Sinzinger,H.,Widhalm,K .,Gall,A. Decreased sensitivity of human platelets to antiaggregatory prostaglandins (PGI PGEl, PGD ) in patients with different types of hyperlipopro 4'. einemia (sul& mitted for publication). 9. Silberbauer,K.,Schernthaner,G.,Sinzinger,H.,Piza-Katzer,H.,Winter,M. Decreased vascular prostacyclin in juvenile-onset diabetes. The New Engl. J. Med. 1979, 400, 366. 10. D'Angelo,V.,Villa,S.,Mysliwiec,M.,Donati,~.B.,DeGaetano,G. Defective fibrinolytic and prostacyclin-like activity in human atheromatous plaques. Thromb. Haemost. 1978, 39, 535. Effect of 11. Silberbauer,K.,Clopath,P.,Sinzinger,H.,Schernthaner,G. experimentally induced diabetes on swine vascular prostacyclin (PG12-)synthesis. Artery 1980, 8, 30. 12. Sinzinger,H.,Clopath,P.,Silberbauer,K. minipig aortic prostacyclin formation 1980, 8, 23.
The effect of ballooning - a time course. Artery
on
13. Siegl,A.M.,Smith,J.B.,Silver,M.J.,Nicolaou,K.C.,Ahern,D. Selective binding site for 3H-prostacyclin on platelets. J. Clin. Invest. 1979, 63, 215. 14. Garcia-Conde,J.,Amado,J.A.,Merino,J.,Benet,I. Prostaglandins and platelet function in diabetes. Thromb. Haemost. 1979, 42, 798. 15.
Klein,K.,Kaliman,J.,Sinzinger,H.,Silberbauer,K. Plattchensensitivitat fiir Prostacyclin bei diabetischen und nicht-diabetischen Patienten mit atherosklerotischen GefaBveranderungen - ein MaB fiir die Prostacyclinrezeptoren der Plattchenmembran ? VASA 1980, 9, 123.
16. Klein,K .,Sinzinger,H., Silberbauer,J.Kaliman. Enhanced prostacyclin formation but normal platelet sensitivity in women taking oral contraceptives. Pharm. Res. Comm. 1980, 4, 325. Decreased platelet sensitivity to the an17. Kaliman,J.,Sinzinger,H. tiaggregatory prostaglandins in patients with peripheral vascular disease. (submitted for publication). 18. Kaliman,J.,Sinzinger,H.,Widhalm,K.,Probst,P.,Pachinger,O. Serum lipoproteins and platelet function in patients with myocardial infarction below the age of 40. Proceedings of the Meeting "Myocardial infarction at young age", Bad Krozingen, January 1981, H. Roskam (ed.).
132