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Effect of pyloric ligation on the gastric secretion of dissolved mucins in fasting rats
Lüe Sciences Vol . 10, Part I, pp. 541-548, 1971 . Printed in Great Britain
Pergamon Press
EFFECT OF PYLORIC LIGATION ON THE GASTRIC SECRETION OF DISSOLVED
MUCINS
IN
FASTING RATS . A. Lietti and G. Prino Crinos S.p .A ., Biological Research Laboratories, Villa Guardia (Como)
Italy
(Received in final form 22 March 1971) Summer : Two macros fractions: "glandular mucoprotein" and "mucoproteose", which were seen in human gastric juice, can be separatedin rat gastric aecre
tion also after pyloric ligation . We found that the secretion of "glandular mucoprotein" paralleled that of the peptic activity while the "mucoproteoae" was released at a rate comparable to that of the secretory volume . A comparison between the increase is ulceration produced by pyloric ligation and the output of mucus, peptic activity and hydrogen ions is presented .
The pyloric ligation technique is widely used to induce gastric ulceration in rats (1) . It was pointed out by Sun and Chen (2) that the increased
secre
tioas of hydrochloric acid and pepsin are essential factors in the production of lesions . The kinetics of acid (3,4) and peptic ($) secretion have also been investigated . The effect of rat pyloric ligation on the release of gastric mu~ cue has, however, not been demonstrated yet. Glass was able to separate two mu cin fractions from human gastric secretion, viz .,
"glandular mucoprotein"
a.nd
"mucoproteose" . The former was from the fondue glands and increased following vagal stimulation, and the latter was probably from secretions of the surface epithelium (6) . The ai.m of this study was to examine the effect of increasing times of pyloric ligation on dissolved mucins in gastric secretion. At the same time acid and pepsin secretion and the degree of gastric ulceration were deter mined. Materials and Methods Male Sprague Dawley rata we ighing about 200g were fasted for 48 hours but given water ad libitum. They were kept singly in cages with wire net bottoms to avoid coprophagy . The animals were subjected to pyloric ligation under light ether anaesthesia and were sacrificed after 90, 180 or 360 min. The stomachs were removed,,freed of their contents sad the degree of ulceration determined . For the evaluation of ulcer, the following scores were used 541
542
Gastric Secretion of Fasting Rats "0 .5" :
Vol . 10, No . 10
for haemorrhages or erosions or for each small ulcer (< 3mm)
" 1 " : for each marked ulcer (> 3~) " 5 " : for a perforated ulcer (or as ma xim,~m score) The measurement of total acidity, peptic activity and of the two dissolved macro fractions was performed on the undiluted gastric content of each rat. To tat acidity was determined by titrating gastric juice with 0 .01 N NaOH using phenolphtalein as indicator. In order to eliminate the insoluble mucus,
the gastric juices were fitte
red through gauze and centrifugated first at $,000 xg for 10 min and then at 30,000 xg for 20 min. The peptic activity and the two mucoprotein fractions we re measured in the supernate . To 1 volume of the supernate, 0.5 vol. of trichlo roacetic acid (TCA) 10~ was added. To enhance precipitation of serum proteins the mixture was left standing overnight at 4°C. After centrifugation at $,000 xg for 1$min, a small aliquot of supernate was used for peptic activity determina tions and two ml were kept for the determination of dissolved mucins by a slight modification of Glass' fractionation method (7) . These modifications consisted of prolonging the incubation with acetone for 2 hours and separating the "glan dular mucopretein" from "mucoproteose" by centrifugatiog at 30,000 xg for 20min. The presence of TCA did not denature rat gastric proteases . To substantiate this point each of 6 pools of rat gastric juice was divided into two portions : one was treated with TCA as previously described and the other with HC1 0 .1 N. One ml of TCA treated juices released 8 .$7 ~ 0.35 identical value,
moles Irtyrosine/hr and an almost
8 .54 f 0.45, was found for the juices TCA free .
Peptic activity was measured on albumin substrate . Two tenth mla of gastric juice were added to 1 ml of 0.5~ bovine cristalline albumin solution in 0.01 N HC1, pH 2, and incubated for 20 min at 37°C . A background control tube (gastric juice blank) was run simultaneously, in which albumin was replaced by 1 ml of 0.01 N HC1. The hydrolysis was stopped by adding 2 ml of 10~ TCA . All tubes were placed in a boiling water bath for 5 min, cooled and filtered through Whatman n° 42 filter paper . To 2 ml of the filtrate were added 0.8 ml of 2.$ N NaOH and 0.2m1 of Folin Ciocalteu reagent . The volume was brought to 20m1 with distilled water and absorbancy was measured at 700 nm . Total hexoses of the mucin fractions were measured with the anthrone method (8) and expressed as galactose.
Vol . 10, No . 10
Cxastric Secretion od Fasting Rats
TA~.E
543
1
Effect of Pyloric Ligation on Rat Gastric Secretion (Mean Values f 3,E .) .
Period of pyloric ligation 18o e~ from
I
90
(14)
(12)
I
160 (13)
I
90~
from
~90+
Volume Output
ml
Secretion rate
ml~hr
2,9 f
0.3
6.1 f
o .4~
1 .9 f
0.2
2.0 f
0,1
+107
8,8 f
o.6x~°
+200
1.j t 0,1°
- 25
Total acidity Output 1~Q
305 .9 f 35 .9
991 .7 f 55 .1~
+224
1056 .E f 64 .9~
+245
204 .8 f 24 .2
332 .1 f 17 .7~
+ 62
176.1 f 10 .8°
- 14
Secretion rate ~Q~~~ Peptic activity Output
tyrosine
moles
Secretion rate
tyros .umoles/hr
1.3
30 .5 f
3.8~
+210
60,1 f
8.0~°
+511
6.6 t 0.8
10 .2 f
1 .3~
+ 55
lo .o f
1 .3#
+ 53
266.9 f 24 .1~
+205
9 .8 f
Glandular mucoproteina Output
tyrosine ~g Secretion rate
tyrosine ~g/hr
87 .4 f 13 .E 58 .2 t 9.1
89 .o f
S .o*
+ 53
160.4 t 14 .5~
+106
480.4 f 37 .9#° 80,2 f
6,3#
+450 + 38
Muconroteose Output
tyrosine ug
77 .9 f
9.5
Secretion rate tyrosine ~g/hr
51 .9 f
6 .3
53 .5 f
4.9
273 .3 f 22 .3~°
3
45 .E f
- In brackets : number of animals ~ Significantly different fron
90~ group
~ Significantly different from
180 group
3 .7
+251 12
544
C,'aetric Secretion of Fasting Rats
Vol. 10, No. 10
Results Table 1 shows the effects induced by pyloric ligation on the following parameters of rat gastric secretion: volume, total acidity, peptic activity and soluble mucins secretion. The percent changes in output or secretion rate were calculated with respect to the values obtained after 90 min of pyloric ligation . The rate of gastric juice secretion was constant up to 3 hours after ligation and then decreased. The same behaviour was observed for the'~ucoproteo se" fraction . On the other hand, the rate of pepsin, "glandular mucoprotein" and acid secretion increased markedly (55X, 53% and 62~, respectively) between 90 and 180 min of pyloric ligation . No further increase in these parameters could
be seen at 360 min and in fact acid secretion declined by 14X with
respect to the 90 min value . The ratio between the secretion rate of pepsin (expressed as umoles tyrosine released by 1 ml of gastric juice/hr) and that of "glandular mucoprotein"
(as ~g of tyrosine/ml of gastric juice/hr) did not vary
with time . Taking the whole gastric secretion into consideration it can be seen that at 6 hours the greatest rise in output was shown by the peptic activity and by the "glandular mucoprotein" fraction . It was approximately double the rise
in
gastric juice volume, total acidity and "mucoproteose" . Table 2,summarizes experiments performed on 9 pools of rat gastric
juice
for each pyloric ligation time . Tyrosine and total hexoses content of the solu ble mucin fractions were determined . The "glandular mucoprotein" was characterized by a greater protein to hexo se ratio (total hexoses/tyrosine ratio between 0 .74 and 0 .93) while the proteose" was represented by a major glucidic portion revealed by a total
"muco hexo
ses/tyrosine ratio between 3 .43 and 3 .93 . pyloric ligation induced an increase in "glandular mucoprotein" concentration based both on increases in total ses and tyrosine . In fact, at 180 min, tein" fraction increased by 43X,
hexo
total hexoses of the "glandular mucopro
and tyrosine content by 61X while at 360
min
the increases were 88X and 128X, respectively . The hexoses and tyrosine contents of the soluble "mucoproteose" fraction of gastric juice increased only slightly at 180 min while larger increases were observed after 360 min of pyloric tion (58X and 39X increases, respectively) .
liga
voi . io, xo. i o
Gastric Secretion oaf Fasting Rats
545
TABLE 2 Tyrosine and total Hexoses content in Dissolved Nucoprotein and Mucoproteoae of Rat Gastric Juice . Each Figure is the mean of 9 Pools of gastric juice. Each pool is made up of 4 juices . Period of pyloric ligation 90'
~
180'
from 90'
360'
from 90'
Qandular muc~rotein Total hexoses
pg/ml
29 .3 f 2 .4
42 .o f 5 .7.x~
+ 43 .4
55 .o f 5 .8~
Tyrosine
~g/ml
3z .4 f 2.1
5z .1 f 1.3~
+ 61 .1
73 .7 f 2.0°~ +127 .9
0 .9 f o.1
0.8 f o.1
- 11 .8
Total hexoses/tyrosine ratio
0.7 f o.1
+ 87 .8 - 20 .4
Hucoproteose Total hexoses
~g/ml
83 .1 f 6.2
89 .5 f 5.7
+ 7 .7 ~31 .5 t.7 .1°* + 58 .2
Tyrosine
pg/ml
24 .1 t 1.2
24 .8 f o.8
+ ~ 2 .8
3 .4 f o.1
3 .6 f 0 .3
+ 6 .1
Total hexoses/tyrosine ratio
33 .6 f 1 .1°~ + 39 .2 3 .9 f o.2
+ 14 .6
Significantly different from 90' group ° Significantly different from 180' group
Figure 1 shows a comparison between the total output of the eac~~n ed parameters of rat gastric secretion and the severity of the lesions.
Fic. 1
Variation in gastric secretion output (data of table 2) and ulcer severity in the same animals . The data were calculated after setting = 100 the parameters wean values at 90 min of pyloric ligation . A m ulcer severity ; B m total acidity; C - gastric juice volume ; D s peptic activity ; E - "glandular mucoprotein ; F = "mucoproteose" .
546
Gastric Secretion of Fasting Rats
Vol . 10, No . 10
The ulceration was small between 90 and 180 min after pyloric ligation but then worsened greatly at 360 min. The percent increase in the ulcer severity was tom parable to the percent increase in pepsin and "glandular mucoprotein" output at 360 min .
Discussion
Pyloric ligation in the rat produces a hypersecretion of gastric juice which is characterized by a marked increase in total acidity (3) and pepsin con centration ($) . Our findings demonstrate that mucous secretion also is affected by this experimental technique . Our interest was focused on the dissolved matins of gastric juice which were measured according to the fractionation method
by
Glass (7) . We found that in rat gastric juice it was possible to differentiate two main classes of dissolved matins . One of these fractions,
the so-called "mucoproteose" fraction was characters
zed by a greater carbohydrate content, evidenced by a total hexose/tyrosine ratio of about 3 .6 . The second fraction,"glandular mucoprotein" revealed a significant protest component and a total hexose/tyrosine ratio
of about 0.8 . Qass found a
total hexose/tyrosine ratio of about 8 .$ for dissolved" mucoproteo.ae" and a ratio of about 0 .$ for dissolved"glandular mucoprotein" in human gastric
juice (6) .
The output of these two macro fractions increased with the duration of pY loric ligation but their respective rates of secretion were sharply different . The"mucoproteose" fraction was released into the gastric lumen at a constant ra to and its output strictly paralleled the outflow of total fluid. On the contra
I9, the"glandular mucoprotein" fraction was characterized by an increased rate of secretion between 90 and 180 min and then remained constant for the following three hours . The secretioy behaviour of "glandular mucoprotein"
was almost iden
tical to that displayed by the peptic activity, The secretioy rate of hydrogen ions was peculiar ; a marked rise occurred in the secretion rate between 90 and 180 min was followed by a comparable steep de crease . The decline could have been due to the inhibitory effect exerted by the raised endogastric pressure (9) . The close relationship between the secretion of peptic activity and a solu ble macro fraction suggested the possibility that pepsin could be present in the rats stomach as a glycoproteic complex. This would be similar to that in man (6) and dogs (10) .
Vol . 10, No . 10
Gastric Secretion of Fasting Rats
547
Nevertheless, the possibility exists that, as was shown by Schrager (11), the measurement of dissolved'g].andular mucoprotein" by means of its tyrosine con tent would estimate only pepsin which was not precipitated by TCA, Our experi means demonstrate, however, that the concentration of "glandular mucoprotein" was increased with the duration of pyloric ligatioa when measured by means of glucidic content. The secretion features of the "mucoproteose" fraction auggea ~ed that this macro class is of different cellular derivation from that of "glandular mucoprotein", In the rat "mucoproteose" could be derived also from the secretion of surface epithelial glands, which has a protective role (6), Plotting the increase in the severity of the lesions against the time of pyloric ligation we noticed that the severity of ulcers showed a percent incre ment of the same order as that manifested by the output of "glandular mucopro taro" and peptic activity . At the same time it appeared that the difference in output between "mucoproteoae" on one sides and "glandular mucoprotein" and pep sin on the other, increased progressively with time . Acknowledgements We thank Dr . Gianfranca Nardi for her helpful suggestions . The assistance of Mr . Giovanni Ghiazone is greatly appreciated . References H. Shap, S.A . Komarov, S,S. Fels, D. Meranze, M. Gruenatein and H.A, Siplet, Gastroenterolopy, ~,
2.
D.C, Sun and J.K . Chen in "Pathophpsioloas of Peptic Ulcer" (Ed. S,C. Skor~ na) p.
3.
141,
McGill University Press, Canada
D.A . Brodie, Am . J, dig. Dis .,
4. x. 5.
q3 (1945)
Ishü, Jap, J . Pharmacol.,
(1963) .
11,
231 (1966) .
~
125 (1969) .
H.I . Hirachowitz, D.K . O~Leary and LN. Marks, Am. J . Phvsiol ., ~
108
(1960) .
6.
G.B,J . Glana, Ann. N.Y . Acad . Sci,, 1~0, art.
2, 80¢ (1967) .
7.
G.B,J . Qass and L,J. Hoyd, Gastroeaterolo~y,
12, 821 (1949),
8.
T.A . Scott and E,H . Melvin, Anal . Chem ,, ~
9.
G. F. Korot'ko and A .M . Musaev, Hyull, eksper . Biol . Med., Trass. Hull . exp. Biol . Med.,
~
1091
1656 (1953) .
-,8 22 (1969) 6
(1969),
J. De Graef, A . Gerard, R. Lev. and G.H .J . Glana in "The Physiolo~ of
548
Gastric Secretion od Fasting Rats
Vol. 10, No . 10
Gastric Secretion" (Eds . L.S, Semb and J . Myren) p. 124, Universitetsforla get, Oslo, 1968, 11, J,
Schrager, Gut, 2, 37 (1961),
Pergamon Press
EFFECT OF PYLORIC LIGATION ON THE GASTRIC SECRETION OF DISSOLVED
MUCINS
IN
FASTING RATS . A. Lietti and G. Prino Crinos S.p .A ., Biological Research Laboratories, Villa Guardia (Como)
Italy
(Received in final form 22 March 1971) Summer : Two macros fractions: "glandular mucoprotein" and "mucoproteose", which were seen in human gastric juice, can be separatedin rat gastric aecre
tion also after pyloric ligation . We found that the secretion of "glandular mucoprotein" paralleled that of the peptic activity while the "mucoproteoae" was released at a rate comparable to that of the secretory volume . A comparison between the increase is ulceration produced by pyloric ligation and the output of mucus, peptic activity and hydrogen ions is presented .
The pyloric ligation technique is widely used to induce gastric ulceration in rats (1) . It was pointed out by Sun and Chen (2) that the increased
secre
tioas of hydrochloric acid and pepsin are essential factors in the production of lesions . The kinetics of acid (3,4) and peptic ($) secretion have also been investigated . The effect of rat pyloric ligation on the release of gastric mu~ cue has, however, not been demonstrated yet. Glass was able to separate two mu cin fractions from human gastric secretion, viz .,
"glandular mucoprotein"
a.nd
"mucoproteose" . The former was from the fondue glands and increased following vagal stimulation, and the latter was probably from secretions of the surface epithelium (6) . The ai.m of this study was to examine the effect of increasing times of pyloric ligation on dissolved mucins in gastric secretion. At the same time acid and pepsin secretion and the degree of gastric ulceration were deter mined. Materials and Methods Male Sprague Dawley rata we ighing about 200g were fasted for 48 hours but given water ad libitum. They were kept singly in cages with wire net bottoms to avoid coprophagy . The animals were subjected to pyloric ligation under light ether anaesthesia and were sacrificed after 90, 180 or 360 min. The stomachs were removed,,freed of their contents sad the degree of ulceration determined . For the evaluation of ulcer, the following scores were used 541
542
Gastric Secretion of Fasting Rats "0 .5" :
Vol . 10, No . 10
for haemorrhages or erosions or for each small ulcer (< 3mm)
" 1 " : for each marked ulcer (> 3~) " 5 " : for a perforated ulcer (or as ma xim,~m score) The measurement of total acidity, peptic activity and of the two dissolved macro fractions was performed on the undiluted gastric content of each rat. To tat acidity was determined by titrating gastric juice with 0 .01 N NaOH using phenolphtalein as indicator. In order to eliminate the insoluble mucus,
the gastric juices were fitte
red through gauze and centrifugated first at $,000 xg for 10 min and then at 30,000 xg for 20 min. The peptic activity and the two mucoprotein fractions we re measured in the supernate . To 1 volume of the supernate, 0.5 vol. of trichlo roacetic acid (TCA) 10~ was added. To enhance precipitation of serum proteins the mixture was left standing overnight at 4°C. After centrifugation at $,000 xg for 1$min, a small aliquot of supernate was used for peptic activity determina tions and two ml were kept for the determination of dissolved mucins by a slight modification of Glass' fractionation method (7) . These modifications consisted of prolonging the incubation with acetone for 2 hours and separating the "glan dular mucopretein" from "mucoproteose" by centrifugatiog at 30,000 xg for 20min. The presence of TCA did not denature rat gastric proteases . To substantiate this point each of 6 pools of rat gastric juice was divided into two portions : one was treated with TCA as previously described and the other with HC1 0 .1 N. One ml of TCA treated juices released 8 .$7 ~ 0.35 identical value,
moles Irtyrosine/hr and an almost
8 .54 f 0.45, was found for the juices TCA free .
Peptic activity was measured on albumin substrate . Two tenth mla of gastric juice were added to 1 ml of 0.5~ bovine cristalline albumin solution in 0.01 N HC1, pH 2, and incubated for 20 min at 37°C . A background control tube (gastric juice blank) was run simultaneously, in which albumin was replaced by 1 ml of 0.01 N HC1. The hydrolysis was stopped by adding 2 ml of 10~ TCA . All tubes were placed in a boiling water bath for 5 min, cooled and filtered through Whatman n° 42 filter paper . To 2 ml of the filtrate were added 0.8 ml of 2.$ N NaOH and 0.2m1 of Folin Ciocalteu reagent . The volume was brought to 20m1 with distilled water and absorbancy was measured at 700 nm . Total hexoses of the mucin fractions were measured with the anthrone method (8) and expressed as galactose.
Vol . 10, No . 10
Cxastric Secretion od Fasting Rats
TA~.E
543
1
Effect of Pyloric Ligation on Rat Gastric Secretion (Mean Values f 3,E .) .
Period of pyloric ligation 18o e~ from
I
90
(14)
(12)
I
160 (13)
I
90~
from
~90+
Volume Output
ml
Secretion rate
ml~hr
2,9 f
0.3
6.1 f
o .4~
1 .9 f
0.2
2.0 f
0,1
+107
8,8 f
o.6x~°
+200
1.j t 0,1°
- 25
Total acidity Output 1~Q
305 .9 f 35 .9
991 .7 f 55 .1~
+224
1056 .E f 64 .9~
+245
204 .8 f 24 .2
332 .1 f 17 .7~
+ 62
176.1 f 10 .8°
- 14
Secretion rate ~Q~~~ Peptic activity Output
tyrosine
moles
Secretion rate
tyros .umoles/hr
1.3
30 .5 f
3.8~
+210
60,1 f
8.0~°
+511
6.6 t 0.8
10 .2 f
1 .3~
+ 55
lo .o f
1 .3#
+ 53
266.9 f 24 .1~
+205
9 .8 f
Glandular mucoproteina Output
tyrosine ~g Secretion rate
tyrosine ~g/hr
87 .4 f 13 .E 58 .2 t 9.1
89 .o f
S .o*
+ 53
160.4 t 14 .5~
+106
480.4 f 37 .9#° 80,2 f
6,3#
+450 + 38
Muconroteose Output
tyrosine ug
77 .9 f
9.5
Secretion rate tyrosine ~g/hr
51 .9 f
6 .3
53 .5 f
4.9
273 .3 f 22 .3~°
3
45 .E f
- In brackets : number of animals ~ Significantly different fron
90~ group
~ Significantly different from
180 group
3 .7
+251 12
544
C,'aetric Secretion of Fasting Rats
Vol. 10, No. 10
Results Table 1 shows the effects induced by pyloric ligation on the following parameters of rat gastric secretion: volume, total acidity, peptic activity and soluble mucins secretion. The percent changes in output or secretion rate were calculated with respect to the values obtained after 90 min of pyloric ligation . The rate of gastric juice secretion was constant up to 3 hours after ligation and then decreased. The same behaviour was observed for the'~ucoproteo se" fraction . On the other hand, the rate of pepsin, "glandular mucoprotein" and acid secretion increased markedly (55X, 53% and 62~, respectively) between 90 and 180 min of pyloric ligation . No further increase in these parameters could
be seen at 360 min and in fact acid secretion declined by 14X with
respect to the 90 min value . The ratio between the secretion rate of pepsin (expressed as umoles tyrosine released by 1 ml of gastric juice/hr) and that of "glandular mucoprotein"
(as ~g of tyrosine/ml of gastric juice/hr) did not vary
with time . Taking the whole gastric secretion into consideration it can be seen that at 6 hours the greatest rise in output was shown by the peptic activity and by the "glandular mucoprotein" fraction . It was approximately double the rise
in
gastric juice volume, total acidity and "mucoproteose" . Table 2,summarizes experiments performed on 9 pools of rat gastric
juice
for each pyloric ligation time . Tyrosine and total hexoses content of the solu ble mucin fractions were determined . The "glandular mucoprotein" was characterized by a greater protein to hexo se ratio (total hexoses/tyrosine ratio between 0 .74 and 0 .93) while the proteose" was represented by a major glucidic portion revealed by a total
"muco hexo
ses/tyrosine ratio between 3 .43 and 3 .93 . pyloric ligation induced an increase in "glandular mucoprotein" concentration based both on increases in total ses and tyrosine . In fact, at 180 min, tein" fraction increased by 43X,
hexo
total hexoses of the "glandular mucopro
and tyrosine content by 61X while at 360
min
the increases were 88X and 128X, respectively . The hexoses and tyrosine contents of the soluble "mucoproteose" fraction of gastric juice increased only slightly at 180 min while larger increases were observed after 360 min of pyloric tion (58X and 39X increases, respectively) .
liga
voi . io, xo. i o
Gastric Secretion oaf Fasting Rats
545
TABLE 2 Tyrosine and total Hexoses content in Dissolved Nucoprotein and Mucoproteoae of Rat Gastric Juice . Each Figure is the mean of 9 Pools of gastric juice. Each pool is made up of 4 juices . Period of pyloric ligation 90'
~
180'
from 90'
360'
from 90'
Qandular muc~rotein Total hexoses
pg/ml
29 .3 f 2 .4
42 .o f 5 .7.x~
+ 43 .4
55 .o f 5 .8~
Tyrosine
~g/ml
3z .4 f 2.1
5z .1 f 1.3~
+ 61 .1
73 .7 f 2.0°~ +127 .9
0 .9 f o.1
0.8 f o.1
- 11 .8
Total hexoses/tyrosine ratio
0.7 f o.1
+ 87 .8 - 20 .4
Hucoproteose Total hexoses
~g/ml
83 .1 f 6.2
89 .5 f 5.7
+ 7 .7 ~31 .5 t.7 .1°* + 58 .2
Tyrosine
pg/ml
24 .1 t 1.2
24 .8 f o.8
+ ~ 2 .8
3 .4 f o.1
3 .6 f 0 .3
+ 6 .1
Total hexoses/tyrosine ratio
33 .6 f 1 .1°~ + 39 .2 3 .9 f o.2
+ 14 .6
Significantly different from 90' group ° Significantly different from 180' group
Figure 1 shows a comparison between the total output of the eac~~n ed parameters of rat gastric secretion and the severity of the lesions.
Fic. 1
Variation in gastric secretion output (data of table 2) and ulcer severity in the same animals . The data were calculated after setting = 100 the parameters wean values at 90 min of pyloric ligation . A m ulcer severity ; B m total acidity; C - gastric juice volume ; D s peptic activity ; E - "glandular mucoprotein ; F = "mucoproteose" .
546
Gastric Secretion of Fasting Rats
Vol . 10, No . 10
The ulceration was small between 90 and 180 min after pyloric ligation but then worsened greatly at 360 min. The percent increase in the ulcer severity was tom parable to the percent increase in pepsin and "glandular mucoprotein" output at 360 min .
Discussion
Pyloric ligation in the rat produces a hypersecretion of gastric juice which is characterized by a marked increase in total acidity (3) and pepsin con centration ($) . Our findings demonstrate that mucous secretion also is affected by this experimental technique . Our interest was focused on the dissolved matins of gastric juice which were measured according to the fractionation method
by
Glass (7) . We found that in rat gastric juice it was possible to differentiate two main classes of dissolved matins . One of these fractions,
the so-called "mucoproteose" fraction was characters
zed by a greater carbohydrate content, evidenced by a total hexose/tyrosine ratio of about 3 .6 . The second fraction,"glandular mucoprotein" revealed a significant protest component and a total hexose/tyrosine ratio
of about 0.8 . Qass found a
total hexose/tyrosine ratio of about 8 .$ for dissolved" mucoproteo.ae" and a ratio of about 0 .$ for dissolved"glandular mucoprotein" in human gastric
juice (6) .
The output of these two macro fractions increased with the duration of pY loric ligation but their respective rates of secretion were sharply different . The"mucoproteose" fraction was released into the gastric lumen at a constant ra to and its output strictly paralleled the outflow of total fluid. On the contra
I9, the"glandular mucoprotein" fraction was characterized by an increased rate of secretion between 90 and 180 min and then remained constant for the following three hours . The secretioy behaviour of "glandular mucoprotein"
was almost iden
tical to that displayed by the peptic activity, The secretioy rate of hydrogen ions was peculiar ; a marked rise occurred in the secretion rate between 90 and 180 min was followed by a comparable steep de crease . The decline could have been due to the inhibitory effect exerted by the raised endogastric pressure (9) . The close relationship between the secretion of peptic activity and a solu ble macro fraction suggested the possibility that pepsin could be present in the rats stomach as a glycoproteic complex. This would be similar to that in man (6) and dogs (10) .
Vol . 10, No . 10
Gastric Secretion of Fasting Rats
547
Nevertheless, the possibility exists that, as was shown by Schrager (11), the measurement of dissolved'g].andular mucoprotein" by means of its tyrosine con tent would estimate only pepsin which was not precipitated by TCA, Our experi means demonstrate, however, that the concentration of "glandular mucoprotein" was increased with the duration of pyloric ligatioa when measured by means of glucidic content. The secretion features of the "mucoproteose" fraction auggea ~ed that this macro class is of different cellular derivation from that of "glandular mucoprotein", In the rat "mucoproteose" could be derived also from the secretion of surface epithelial glands, which has a protective role (6), Plotting the increase in the severity of the lesions against the time of pyloric ligation we noticed that the severity of ulcers showed a percent incre ment of the same order as that manifested by the output of "glandular mucopro taro" and peptic activity . At the same time it appeared that the difference in output between "mucoproteoae" on one sides and "glandular mucoprotein" and pep sin on the other, increased progressively with time . Acknowledgements We thank Dr . Gianfranca Nardi for her helpful suggestions . The assistance of Mr . Giovanni Ghiazone is greatly appreciated . References H. Shap, S.A . Komarov, S,S. Fels, D. Meranze, M. Gruenatein and H.A, Siplet, Gastroenterolopy, ~,
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