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Thrombi formation parameters in mesenteric arterioles and venules in rats
THROMBOSIS RESEARCH 72; 347352,1993 00493848/93 $6.00 + .OO Printed in the USA. Copyright (c) 1993 Pergamon Press Ltd. All rights reserved.
BRIEF COMMUNICATION THROME41FORMATIOM
PARAMES!RRS IN MEZZNTERIC VENULES IN RATS
ARTERIOLES AND
N.N. Petrishchev, 1-A. Mikhailova St -Petersburg
(Received
Medical Institute, Lev Tolstoy str., 6/8, St-Petersburg, Russia 11 .1.1993; accepted in revised form 21.7.1993 by Editor V.K. Kibirev) (Received by Executive Editorial Office 31.8.1993)
Cellular elements.in the walls of arteries and veins demonstrate different activity in production of substances reaponsible for tbrombus formation. For example, more pro&e&yelin is formed in the arteries of the rats (1). Consequently, differences in the rate of thrombue formation in the arteries and in the veins may be related not only to some hemodynamic factors but also the specificity of thrombogenic and thromboresistant properties of the vessels, which are associated with metabolie conditions of cellular elements:in the vessel wall. The lack of thorough study of the causes of difference in the rate of thrombus formation in the arterial and venous vessels prompted us to undertake the present investigation. Our main object was to study thrombogenic and throtioresistant properties of arterioles and venules using quantitative evaluation of the parameters of the thrombi formation. METHODS AND MATERIALS Initiation of tbrombi formation -in the microcirculation. The dynamics of thrombi growth was studied in arteriole8 and
Key words8
laser, thrombosis, venules, arterioles 347
348
LASER INDUCED THROMBOSIS
Vol. 72, No. 4
venulee (d=40-5Orm) of the mesenterium in rats. Ilrjuryof the luminal surface of the vessels was induced with a laser beam ( h = 337 nm) focused through the microscope (2). Thrombi formation was associated with the ab.sorption of the laser energy by?hemoglobin of the red blood cells. The temperature increase inside the irradiated volume of blood aaused the damage of the vessel wall, Laser irradiation with a wavelength of 33? nm has been shown to have similar thermal injuring effect when applied to the arterioles and venules of the same diameter. This is due to the fact that hemoglob&n and oxyhemoglobin have the same coefficient of absorption at the wavelength of 33'7nm, the cellular components of the vessels wall and of the blood plasma being practically transparent in this wavelength range. We use nitrogen impulse laser with following parameters: the duration of each impulse was lO'*s, the frequency of impulses was 50 Hz, energy of irradiation was 0.002 to 0.04 J. The laser beam diameter on the vascular wall was 10 /u m. Quantitation of - tbrombi formation parameters. TV'-camera and video monitor were used to survey the process of thrombi development. The parameters.under observation were as follows: the time of the thrombus formation from the moment of the wall damage to the detachment of the first embolus (t,); the time of ultimate fixation of the thrombus to the vessel wall (t,); the erea of the thrombus cross section (S); the length of the thrombus along the vessel wall (I,).The quantitation was done at the moment of the first emboUaation. The frequency of the thrombi formation ($6from the total.number of experiments) and the time of primary hemostasis in oases of rupture of the vessels were registered as well. RESULTS The effect of various irradiation energies on thrombi formation parameters is shown in Table 1. Time parameters of thrombi form&ion. The data presented in Table 1 indFoate that the reUtion of the rate of thrombi formation (tl and t2j to the irradk&ion dose is not monotonous. With all irradiation energies studied the rate of thrombi growth was greater in the arterioles than in the venules (p< 0.01).
Vol. 72, No. 4
LASER INDUCED THROMBOSIS
349
TABLE 1 Parametera of Thrombi Formation in the Mesenteric Venules, and Arterioles in Rats
*-Irradiation energy X lo* J
Thrombus formation parameters Mean + SEM
Mumber of observations
t1, s
t2, s
s,,m*
Lpm
Venules
1.0
15 54
200
72
4.0
24
0.2
1722 555 3123 1022
3025 llO+lO 12028 50210
960$0 1050+0 168050
505 56f9 76~5
2280250
9225
Arterioles 0.2
1.0 2.0 4.0
13 47 64 17
521 1622
205
360220
525
455
620&80
449
2022
605
73050
476
3*1
3Ok5
183Ojr70
7oi5
The period of embolization (t,) was longer in the venules than in the arterioles in spite of an increased flow velocity in the latters (p< 0.05). The area of the thrombua cross ,sectiondownward -the blood ---flow. The size of a thrombus is also related to the amount of the laser irradiation focused on the microvessel The area of the thrombus cross section in the irradiated vessels increased with the increase of the irradiation dose and in all obserrations it was larger in the venules than in the arterioles (p< 0.05). The length of a thrombus along the vessel wall. This parameter determines the interaction zone b,etweenthe platelets and the damaged endothelium. Experiments with large energies of ir-
350
LASER INDUCED THROMBOSIS
Vol. 72, No. 4
radiation (0.02 and 0.04 J> showed that in the venules the length of the thrombus was greater than in the arterioles (~(0.05). There is no significant difference in the length of tbrombi in the arterioles when the energy of irradiation was 0.002, 0.01 and 0.02 J. It means that when the irradiation energy increases from 0.002 up to 0,02 J the thrombus grows mainly in the direction across the vascular wall. Frequency of thrombosis. Within the same irradiation energies we evaluated the frequency of thrombua formation (in % to the total number of observations). In the venules it increased from 38&2% to 9524% (with the minimal and maximal irradiation energy respectively), In the arterioles this index ranged from 13*2$ to 72+3%. TABLE 2 Time of Primary Hemostas:is in Cases of Rupture of Arterioles and Penules' (mean +,SEM)
Irradiation energy,
Arterioles number of okervations
0.01 0.02 OS.04
time of primazy hemostasis, s
42 34
16+_3 2025
51
16t5
Venules number of 00aervations 39 40 48
time of pri mary hemostfisis,s 2527 36~10 42ilO
Time of primary hemostasie. The increase of irradiation -energy led to the increasing numb~er of microvessel ruptures (from 15&l% up to 5O;t4$in the venules and from 20&2% up to 6823% in the arterioles). It must be noted that with al.1irradiation doses. studied the number of ruptures of the arterioles
Vol. 72, No. 4
LASER INDUCED THROMBOSIS
351
was larger than the same index of the venules. The time of primary hemostasis was determined after each rupture (see Table 2). It was larger in the venules in comparison to the arterioles (p
352
LASER INDUCED THROMBOSIS
Vol. 72, No. 4
the venules exceeded those of the arterioles. On the basis of these results one may suggest that the difference in the parameters depends on the functional capacity of the vessels rather than on the difference in blood flow velocity. The tendency of blood platelets to aggregate is known to be considerably greater in the arterioles than in the venules (3). This may seem to account for the fact that with the increase of the laser irradiation energy the thrombus in the arterioles grows in the direction of the lumen while in the venules it grows along the vessel wall. It is noteworthy that all irradiation energies used the measured time of primary hemostasis in ruptured microvessels was shorter in the arterioles than in the venules. The above mentioned data show that arterial thrombi (as compared to the venous ones in the microvessels of the same diameter) grow more rapidly, but have less length along the vascu lar wall and lesser sizes. The frequency of thrombosis in the arterioles is less than in the venules, also the time of primary hemostasis is shorter in arterioles. All these facts tes,tify to a greater thrombogenic potential of the arterioles. REFERENCES
1. SKIDGEL R.A., PRINTZ MwI.P. Pg-12-production by rat blood vessels diminish prostacyclin formation in veins compared to arteries. Prostaglandins, l6, 1-16, 1978. 2. ARFCRS K.E., DHALL D.P., BNGESET J. et al. Biolaser endothelial trauma as a means of quantifying platelet activity in vivo. Nature, 218, 887, 1968.
3. DON1 N.G., BOTTECCIA D. What a provoking different aggregation between arterial and venous platelet in rat? Haemosta@, l4, 495-500, 1984.
4. GROOT P.D.,
SIXMA J.J. Platelet adhesion. A concerted action of hemodynamic and biochemic processes. In: New Trends & HAEMOSTASIS. J.Harenberg, D.L. Heene, G,Stehle, G.Schetler (Eds) Berlin, Heidelberg, New York: Springer-Verlag, 1992, p. 69-87.
BRIEF COMMUNICATION THROME41FORMATIOM
PARAMES!RRS IN MEZZNTERIC VENULES IN RATS
ARTERIOLES AND
N.N. Petrishchev, 1-A. Mikhailova St -Petersburg
(Received
Medical Institute, Lev Tolstoy str., 6/8, St-Petersburg, Russia 11 .1.1993; accepted in revised form 21.7.1993 by Editor V.K. Kibirev) (Received by Executive Editorial Office 31.8.1993)
Cellular elements.in the walls of arteries and veins demonstrate different activity in production of substances reaponsible for tbrombus formation. For example, more pro&e&yelin is formed in the arteries of the rats (1). Consequently, differences in the rate of thrombue formation in the arteries and in the veins may be related not only to some hemodynamic factors but also the specificity of thrombogenic and thromboresistant properties of the vessels, which are associated with metabolie conditions of cellular elements:in the vessel wall. The lack of thorough study of the causes of difference in the rate of thrombus formation in the arterial and venous vessels prompted us to undertake the present investigation. Our main object was to study thrombogenic and throtioresistant properties of arterioles and venules using quantitative evaluation of the parameters of the thrombi formation. METHODS AND MATERIALS Initiation of tbrombi formation -in the microcirculation. The dynamics of thrombi growth was studied in arteriole8 and
Key words8
laser, thrombosis, venules, arterioles 347
348
LASER INDUCED THROMBOSIS
Vol. 72, No. 4
venulee (d=40-5Orm) of the mesenterium in rats. Ilrjuryof the luminal surface of the vessels was induced with a laser beam ( h = 337 nm) focused through the microscope (2). Thrombi formation was associated with the ab.sorption of the laser energy by?hemoglobin of the red blood cells. The temperature increase inside the irradiated volume of blood aaused the damage of the vessel wall, Laser irradiation with a wavelength of 33? nm has been shown to have similar thermal injuring effect when applied to the arterioles and venules of the same diameter. This is due to the fact that hemoglob&n and oxyhemoglobin have the same coefficient of absorption at the wavelength of 33'7nm, the cellular components of the vessels wall and of the blood plasma being practically transparent in this wavelength range. We use nitrogen impulse laser with following parameters: the duration of each impulse was lO'*s, the frequency of impulses was 50 Hz, energy of irradiation was 0.002 to 0.04 J. The laser beam diameter on the vascular wall was 10 /u m. Quantitation of - tbrombi formation parameters. TV'-camera and video monitor were used to survey the process of thrombi development. The parameters.under observation were as follows: the time of the thrombus formation from the moment of the wall damage to the detachment of the first embolus (t,); the time of ultimate fixation of the thrombus to the vessel wall (t,); the erea of the thrombus cross section (S); the length of the thrombus along the vessel wall (I,).The quantitation was done at the moment of the first emboUaation. The frequency of the thrombi formation ($6from the total.number of experiments) and the time of primary hemostasis in oases of rupture of the vessels were registered as well. RESULTS The effect of various irradiation energies on thrombi formation parameters is shown in Table 1. Time parameters of thrombi form&ion. The data presented in Table 1 indFoate that the reUtion of the rate of thrombi formation (tl and t2j to the irradk&ion dose is not monotonous. With all irradiation energies studied the rate of thrombi growth was greater in the arterioles than in the venules (p< 0.01).
Vol. 72, No. 4
LASER INDUCED THROMBOSIS
349
TABLE 1 Parametera of Thrombi Formation in the Mesenteric Venules, and Arterioles in Rats
*-Irradiation energy X lo* J
Thrombus formation parameters Mean + SEM
Mumber of observations
t1, s
t2, s
s,,m*
Lpm
Venules
1.0
15 54
200
72
4.0
24
0.2
1722 555 3123 1022
3025 llO+lO 12028 50210
960$0 1050+0 168050
505 56f9 76~5
2280250
9225
Arterioles 0.2
1.0 2.0 4.0
13 47 64 17
521 1622
205
360220
525
455
620&80
449
2022
605
73050
476
3*1
3Ok5
183Ojr70
7oi5
The period of embolization (t,) was longer in the venules than in the arterioles in spite of an increased flow velocity in the latters (p< 0.05). The area of the thrombua cross ,sectiondownward -the blood ---flow. The size of a thrombus is also related to the amount of the laser irradiation focused on the microvessel The area of the thrombus cross section in the irradiated vessels increased with the increase of the irradiation dose and in all obserrations it was larger in the venules than in the arterioles (p< 0.05). The length of a thrombus along the vessel wall. This parameter determines the interaction zone b,etweenthe platelets and the damaged endothelium. Experiments with large energies of ir-
350
LASER INDUCED THROMBOSIS
Vol. 72, No. 4
radiation (0.02 and 0.04 J> showed that in the venules the length of the thrombus was greater than in the arterioles (~(0.05). There is no significant difference in the length of tbrombi in the arterioles when the energy of irradiation was 0.002, 0.01 and 0.02 J. It means that when the irradiation energy increases from 0.002 up to 0,02 J the thrombus grows mainly in the direction across the vascular wall. Frequency of thrombosis. Within the same irradiation energies we evaluated the frequency of thrombua formation (in % to the total number of observations). In the venules it increased from 38&2% to 9524% (with the minimal and maximal irradiation energy respectively), In the arterioles this index ranged from 13*2$ to 72+3%. TABLE 2 Time of Primary Hemostas:is in Cases of Rupture of Arterioles and Penules' (mean +,SEM)
Irradiation energy,
Arterioles number of okervations
0.01 0.02 OS.04
time of primazy hemostasis, s
42 34
16+_3 2025
51
16t5
Venules number of 00aervations 39 40 48
time of pri mary hemostfisis,s 2527 36~10 42ilO
Time of primary hemostasie. The increase of irradiation -energy led to the increasing numb~er of microvessel ruptures (from 15&l% up to 5O;t4$in the venules and from 20&2% up to 6823% in the arterioles). It must be noted that with al.1irradiation doses. studied the number of ruptures of the arterioles
Vol. 72, No. 4
LASER INDUCED THROMBOSIS
351
was larger than the same index of the venules. The time of primary hemostasis was determined after each rupture (see Table 2). It was larger in the venules in comparison to the arterioles (p
352
LASER INDUCED THROMBOSIS
Vol. 72, No. 4
the venules exceeded those of the arterioles. On the basis of these results one may suggest that the difference in the parameters depends on the functional capacity of the vessels rather than on the difference in blood flow velocity. The tendency of blood platelets to aggregate is known to be considerably greater in the arterioles than in the venules (3). This may seem to account for the fact that with the increase of the laser irradiation energy the thrombus in the arterioles grows in the direction of the lumen while in the venules it grows along the vessel wall. It is noteworthy that all irradiation energies used the measured time of primary hemostasis in ruptured microvessels was shorter in the arterioles than in the venules. The above mentioned data show that arterial thrombi (as compared to the venous ones in the microvessels of the same diameter) grow more rapidly, but have less length along the vascu lar wall and lesser sizes. The frequency of thrombosis in the arterioles is less than in the venules, also the time of primary hemostasis is shorter in arterioles. All these facts tes,tify to a greater thrombogenic potential of the arterioles. REFERENCES
1. SKIDGEL R.A., PRINTZ MwI.P. Pg-12-production by rat blood vessels diminish prostacyclin formation in veins compared to arteries. Prostaglandins, l6, 1-16, 1978. 2. ARFCRS K.E., DHALL D.P., BNGESET J. et al. Biolaser endothelial trauma as a means of quantifying platelet activity in vivo. Nature, 218, 887, 1968.
3. DON1 N.G., BOTTECCIA D. What a provoking different aggregation between arterial and venous platelet in rat? Haemosta@, l4, 495-500, 1984.
4. GROOT P.D.,
SIXMA J.J. Platelet adhesion. A concerted action of hemodynamic and biochemic processes. In: New Trends & HAEMOSTASIS. J.Harenberg, D.L. Heene, G,Stehle, G.Schetler (Eds) Berlin, Heidelberg, New York: Springer-Verlag, 1992, p. 69-87.