Effect of intraduodenal sodium bicarbonate in rat and rabbit exocrine pancreatic secretion

The effect of intraduodenal sodium bicarbonate, 0.1 M, on exocrine pancreatic secretion and the release of two peptides, secretin and VIP, was studied in anesthetized rats and rabbits, two species largely used in the gastroenterology laboratories. In the rabbit, intraduodenal sodium bicarbonate perfusion had no effect either on exocrine pancreatic secretion or on portal plasma levels of secretin and VIP. By contrast, in the rat, intraduodenal sodium bicarbonate perfusion significantly increased hydroelectrolyte exocrine pancreatic secretion and portal plasma secretin levels. A clear interspecific difference reflecting the different gastrointestinal physiology of both species is observed.

Cholinergic mechanisms for secretin release after intraduodenal alkalinization in the anaesthetized rabbit

Exocrine pancreatic response to duodenal perfusion with alkaline solutions (pH 11.4) was studied in the anaesthetized rabbit; secretin and vasoactive intestinal polypeptide (VIP) levels in portal plasma were measured and the contribution of cholinergic mechanisms was also evaluated. Intraduodenal perfusion of sodium carbonate stimulated flow rate and bicarbonate output to a maximum of 322 +/- 44 and 609 +/- 105% respectively compared with basal levels. Significant increases of plasma secretin levels, with a maximum of 267 +/- 38% as compared with basal, were also observed. A lower increase in VIP levels (maximum of 151 +/- 12%) was seen. All these effects, except the VIP response, were substantially inhibited by atropine. Our results show that exocrine pancreatic response to intraduodenal sodium carbonate is specifically focused on hydroelectrolytic secretion. Keeping in mind what occurs after intraduodenal alkaline phosphate buffer administration (at the same pH as sodium carbonate: 11.4) it seems that about 50% of the pancreatic response to sodium carbonate may be ascribed to pH and the remaining 50% to the carbonate anion. Moreover, this response would mainly be mediated by secretin, whose release can be facilitated by a cholinergic reflex.

[Can we do without bone gammagraphy in the staging of prostatic cancer?]

Correlation between findings on bone gammagraphy and PSA levels in 144 patients with untreated prostate cancer are analyzed. With prevalence of metastatic disease in 57.6% cases and considering the predictive cut value of metastasis to be 20 ng/ml, there were positive and negative predictive values of 64.9% and 73.9%, with a diagnostic confidence of 66.6%. We conclude that bone gammagraphy is essential for staging prostate cancer even in patients with PSA below 20 ng/ml.

Cerulein-induced acute pancreatitis in the rat. Study of pancreatic secretion and plasma VIP and secretin levels

A study was made with different doses of cerulein (2, 4, 10 and 20 micrograms/kg) administered subcutaneously to rats by four injections at intervals of 1 hr; the aim of this work was to study exocrine pancreatic secretion of the rat under cerulein-induced acute pancreatitis, analyzing enzyme and hydroelectrolyte secretion of pancreatic juice. A further aim was to study the relationship between the dose of cerulein and the plasma levels of peptides controlling hydroelectrolyte secretion of the pancreas, like secretin and vasoactive intestinal peptide (VIP). At the lowest dose schedule, the amounts of total protein and enzymes (amylase and trypsin) in pancreatic juice decreased significantly, plasma amylase increased, and the pancreas became edematous. Higher doses magnified these effects. By contrast, ductular function (flow and HCO3-) was well preserved in cerulein-treated rats, and this was probably due to the significant increase in plasma levels of immunoreactive secretin whereas VIP levels were unchanged. The secretin released by treatment with cerulein is able to palliate the lack of flow from acinar origin that is affected in the process of acute pancreatitis, being a beneficial response to the cerulein treatment.

Cholinergic mechanisms involved in the effect of intraduodenal ethanol on exocrine pancreatic secretion

The effect of intraduodenal ethanol on exocrine pancreas of the rat in basal conditions has been studied. The pancreatic flow rate significantly increased to a maximum of 148% of basal after intraduodenal ethanol whereas only slight increases of protein output were observed. Ethanol perfusion in previously atropinized animals also elicited a significant increase of the flow rate up to a maximum of 177% of basal values but this increase appeared later than that observed in non-atropinized animals. Our results show that the ethanol action is successively stimulant followed by a simultaneously dual and antagonic effect (stimulant and inhibitory). Furthermore, this ethanol effect is mediated by cholinergic mechanisms. Finally, no effect of ethanol on portal plasma secretin and VIP levels was observed in atropinized or non-atropinized animals.

Pancreatic dose dependent effect of intraduodenal HCl in the anesthetized rabbit

1. A dose-response relationship between intraduodenal perfusion of different HCl loads (1.8, 4.5, 9, 18 and 45 mmol/hr) and volume, bicarbonate and protein outputs, from the exocrine pancreas of anaesthetized rabbits was observed. 2. This study also shows a dose-response relationship between the different HCl loads and the porta levels of secretin and VIP. 3. The secretin response showed a marked decrease during the stimulation period and this may suggest the involvement of a neural mechanism. 4. The plasma VIP responses were of a magnitude that might suggest a hormone role for VIP in this effect.

Glucocorticoids effects on exocrine pancreatic secretion in caerulein-induced acute pancreatitis in the rat

The present work reports on exocrine pancreatic secretion in control rats, adrenalectomized rats and hydrocortisone-treated (10 mg/Kg/d) rats during 7 days, under normal conditions and after induction of acute pancreatitis with caerulein (20 micrograms/Kg) by 4 subcutaneous injections at hourly intervals. Pancreatic secretion was seen to be affected by the procedure of adrenalectomy, which led to a marked reduction in the secretion of proteins and amylase with respect to control values. This was probably due to the decrease occurring in the zymogen granules in the acinar cells of the exocrine pancreas, a phenomenon which also led to a decrease in pancreatic weight observed in these animals. Treatment with hydrocortisone induced a decrease in the secretion of proteins and amylase, as well as an increase in pancreatic weight. This agrees with the accepted hypothesis that large amounts glucocorticoids stimulate the synthesis and storage of proteins in the exocrine pancreas, reducing the secretory phase. The administration of high doses of caerulein under these conditions led to acute pancreatitis in the three groups of animals. This was paralleled by a dramatic decrease in protein and amylase secretion and by severe interstitial edema of the pancreas and by increases in serum amylase values. In the case of the animals treated previously with hydrocortisone, the latter were tripled with respect to the control animals. The conclusion is offered that since the storage of enzyme proteins is governed by glucocorticoids, which furthermore increase the sensitivity of the acinar cells to stimulation by secretagogues, the administration of these substances during the development of pancreatic lesions such as acute pancreatitis is highly compromising to the organism.

Caerulein-induced acute pancreatitis in the rat. Pancreatic secretory response to cholecystokinin

The response of pancreatic exocrine secretion to cholecystokinin (CCK), has been studied in experimental acute pancreatitis induced in rats by supramaximal doses of caerulein. Several doses of caerulein were used (4, 20 and 40 micrograms/Kg) and each one was administered by four subcutaneous injections over 3 h at hourly intervals. Pancreatic juice was collected 9 h after the first injection. The caerulein-treated animals showed a statistically significant increase in serum amylase levels. Secretory activity of ductular cells remained unchanged in all the caerulein-treated animals, but total protein and amylase secretion decreased significantly at all the caerulein doses used, both in resting conditions and under stimulation with CCK (1.25 micrograms/Kg/h). Despite this the acinar cells of rats treated with the lowest dose of caerulein retained a certain degree of secretory function since amylase activity in pancreatic juice was greater than in other groups of rats treated with higher doses of caerulein. Moreover, the percentage of increase observed in total protein and amylase in response to CCK respect to basal secretion is similar to that of the untreated animals. At higher doses (20 and 40 micrograms/Kg) the secretory capacity in response to CCK was inhibited. Therefore CCK administration in slight acute pancreatitis could be used as a therapy since it favours the secretion of pancreatic enzymes at percentual levels similar to those of the controls.

Acinar cholecystokinin (CCK) receptors in the exocrine pancreas of the rat: effect of adrenalectomy

The binding of [125I]BH-CCK-8 to membranes of acinar cells from rats at 6 and 21 days after adrenalectomy was studied. The optimum conditions of time and temperature were previously established as being 120 min and 30 degrees C. Under these conditions, the membranes of the adrenalectomized animals of both groups (6 and 21 days) bound more radioligand than those from control rats. However, a qualitative study of the binding showed that the affinities of binding were much lower; in particular, the high affinity receptors had a Kd of 0.94 +/- 0.33 nM in the controls and this was 14.9 +/- 1.29 nM in the 6-day adrenalectomized animals, although the maximum binding capacity did not vary significantly. However, in the case of the low affinity receptors, there was a gradual increase in the maximum binding capacity as the time after adrenalectomy progressed: 717 +/- 121, 1,987 +/- 183, and 10,175 +/- 862 fmol/mg for the control, 6-day, and 21-day adrenalectomized rats, respectively. In the latter situation, the high affinity receptors completely disappeared. These results, which coincide with a marked deficit in protein secretion already described in adrenalectomized rats, can be accounted for in terms of the possible negative cooperativity exerted by the low affinity receptors on the high affinity hormone-receptor complex, the protein secretion of the acinar cells normally mediated by the high affinity receptors becoming paralyzed.

Duodenal alkalinization releases secretin and vasoactive intestinal polypeptide and stimulates exocrine pancreatic secretion in the anesthetized rat

The effect of various intraduodenal alkaline solutions (0.1 M NaHCO3, 0.1 M Na2CO3 and 0.025 M NaOH) on exocrine pancreatic secretion and the release of two peptides, secretin and vasoactive intestinal polypeptide, was studied in anesthetized rats. The flow rate of the pancreatic juice was stimulated up to a maximum of 179, 158 and 180% and the protein output up to 181, 131 and 162% (compared with basal) after duodenal perfusion of, respectively, 0.1 M NaHCO3, 0.1 M Na2CO3 and 0.025 M NaOH. Maximum increases in portal plasma secretin concentrations of 143, 146 and 190% and maximum increases in VIP of 116, 155 and 147% after, respectively, intraduodenal 0.1 M NaHCO3, 0.1 M Na2CO3, and 0.025 M NaOH were found. In conclusion duodenal alkalinization in the rat produces a pancreatic exocrine secretory response that may be partially ascribed to the effect of secretin and VIP.

Alpha-adrenergic influences on exocrine pancreatic secretion in the rabbit

Action of phenylephrine (35 micrograms/Kg/min) alone or previously blocked by phentolamine (100 micrograms/Kg/min) on exocrine pancreatic secretion of anaesthetized rabbits has been studied, in basal state or under stimulation by secretin (1 C.U./Kg/h) or by the octapeptide of cholecystokinin (OP-CCK) (0.15 Ivy dog units/Kg/h). Phenylephrine increased arterial pressure. This effect was blocked by phentolamine. However no variations were seen in pancreatic blood flow in any of the experimental conditions assayed. Phenylephrine produced a secretin-like effect on hydroelectrolytic secretion in basal conditions. This action was maintained after the infusion of secretin but not after OP-CCK. This effect was not blocked by phentolamine. Phenylephrine increased protein secretion in the basal state, an action that was blocked by phentolamine. After secretin or OP-CCK stimulation phenylephrine did not increase protein secretion. It is concluded that phentolamine blocks the effects of phenylephrine on acinar cells but not on ductular cells.

Exocrine pancreas in rabbits fed a copper-deficient diet: structural and functional studies

The effects of a copper-deficient diet supplemented with D-penicillamine on both the structure and exocrine function of the pancreas were studied in rabbits. The pancreases of the animals kept on this diet for 13 weeks showed lesions in the acinar tissue but not in ductal or islet tissue. The weights of the glands were markedly reduced. Copper deficiency caused a slight (non-significant) reduction in the flow of pancreatic juice and in sodium output and significantly decreased chloride output (p less than 0.01). No changes were observed in bicarbonate and potassium output. Total protein and amylase secretions were maintained at clearly detectable levels in pancreatic juice, although they decreased significantly (p less than 0.01 and p less than 0.001, respectively), in the copper-deficient animals compared with the controls. The pancreases of the animals kept on a copper-deficient diet were seen to maintain their capacity for response to secretin, cholecystokinin (CCK), and bethanechol. Our results show that rabbit pancreatic acinar tissue is less sensitive to copper deficiency than that of other species studied. Additionally, the data on secretion of water and electrolytes suggest that in the rabbit the acinar cells may contribute to the secretory process with a chloride-rich fluid.

Effect of alloxan diabetes on exocrine pancreatic secretion in the anesthetized rabbit

The influence of the endocrine pancreas on the exocrine pancreatic secretion of both electrolytes and enzymes was studied in rabbits made diabetic by alloxan administration. No alterations were observed in the flow of pancreatic juice. Bicarbonate concentrations were considerably increased, whereas chloride concentrations were clearly reduced in the alloxan-diabetic rabbits compared with the control animals. Insulin treatment restored anion levels to normal. Similar, although less pronounced changes were seen in the output values of bicarbonate and chloride. There were no significant differences between the control and alloxan-treated animals in the output of sodium and potassium; however, potassium concentrations exhibited a significant rise both in untreated and insulin-treated diabetic rabbits compared with the controls. Total protein and amylase secretion decreased markedly in the diabetic animals. The secretion of amylase was not brought back to control values by additional administration of insulin. These results suggest that the endocrine pancreas plays an extremely important role in exocrine pancreatic function.

Exocrine pancreatic response to isoproterenol in the rabbit under secretin and CCK stimulation

The effect of isoproterenol (0.3 micrograms/Kg/min) on exocrine pancreatic secretion stimulated by secretin (1. C.U./Kg/h) and the octapeptide of cholecystokinin (OP-CCK 0.15 Ivy dog units/Kg/h) was studied in anaesthetized rabbits. Pancreatic blood flow remained unaffected by the action of isoproterenol; however, the administration of the beta-adrenergic agonist over an infusion of secretion an OP-CCK led to an increase in pancreatic juice flow (approximately 146% for secretin and 125% for OP-CCK) and HCO3-output (approximately 194% for secretin and 150% for OP-CCK), a potentiation being observed between the effects of secretin and isoproterenol. This kind of response, independent of vascular changes, is due to a direct action of isoproterenol on the ductular cells. Isoproterenol interferes with the action of secretin and OP-CCK in that it partially inhibits the stimulatory action of OP-CCK on the enzymatic secretion of the acinar cells in the rabbit pancreas and at the same time protein secretion decreases in the presence of secretin.

Exocrine pancreatic response to secretin and bethanechol in rabbits under hypothermia

The effect of the administration of secretin and bethanechol on exocrine pancreatic secretion was studied in rabbits subjected to temperature changes; these involved a drop from 38 degrees C +/- 1 to 28 degrees C +/- 1 (hypothermia) and a subsequent return to 38 degrees C +/- 1 (normothermia). It was observed that hypothermia does not depress the action of secretin on the secretion of fluid, HCO3- and Cl-. Neither was the action of bethanechol on the enzyme secretion affected by changes in body temperature.

The effect of hypothermia on exocrine pancreatic secretion in rabbits

The effects of experimentally induced hypothermia on exocrine pancreatic secretion in rabbits were investigated. During hypothermia the flow of pancreatic juice decreased to 50% of basal values and recovered after rewarming. Hypothermia scarcely affected HCO-3, Cl- and Na+ concentrations but did cause significant alterations in K+ concentrations. During hypothermia and later normothermia a parallel secretion in the enzymes amylase, chymotrypsin and trypsin was seen to take place. Enzyme secretion decreased throughout the experimental period in the rabbits undergoing hypothermia and later normothermia, as in the case of the control animals.

[Nervous system regulation of exocrine pancreatic secretion in the chicken]

Acute assays were carried out using broiler chickens in which a reentry catheter had previously been placed chronically in the main pancreatic duct. Samples of pancreatic juice were collected after manoeuvres of blockage and stimulation with different neurotransmitters and blocking agents, both cholinergic and adrenergic, as well as electrical stimulation of the left vagosympathetic trunk. Stimulation of the vagus nerve induced a marked increase in the pancreatic flow but with no changes in the enzyme content. Acetylcholine was seen to cause a slight but significant increase in pancreatic flow and a non-significant increase in amylase activity. The drop in the flow of pancreatic juice in response to adrenaline was not very sensitive to adrenergic blockers. The effect of adrenaline on pancreatic secretion cannot be attributed to vascular changes.

A monoclonal antibody GR2110 reactive with a P24 antigen present in a subgroup of acute lymphoid leukemias

A monoclonal antibody IgG1K against a P24 antigen has been obtained. This antigen is present on a subgroup of non-T-ALL and platelets. GR2110 monoclonal antibody was produced by immunizing with a CALL (CALLA+, Ia+, IgS-, E-, T3-) This P24 antigen is absent in normal T-lymphocytes, monocytes, mitogen-activated T-cells; weakly expressed on B-cells and granulocytes and negative with several cell lines, except with KM3. GR2110 monoclonal antibody was tested with chronic and acute human leukemias. It was positive only with some CALL, NULL ALL, B-ALL and negative with B-CLL, T-CLL, T-cell lymphoma, Hairy cell leukemia, AML, T-ALL. The immunoprecipitation of 125I-labeled cell membrane with the monoclonal antibody and SDS-PAGE analysis revealed a 24 kD molecular weight polypeptide. The comparison of GR2110 and FMC 8 in capping experiments and cellular reaction patterns, showed that both antibodies react with the same molecule but probably with different epitopes.

A comparison of the effect of bile salts on maximal hepatic excretion of certain organic anions in the rabbit under urethane and pentobarbitone

The influence of two different anaesthetics, sodium pentobarbitone and ethyl urethane, on the enhancement of maximal bilirubin and bromosulphthalein (BSP) excretion induced by bile salts was investigated in rabbits. Two micelle-forming (glycodeoxycholate and taurocholate) and one non-micelle-forming (dehydrocholate) bile salts were used. Under urethane anaesthesia the bile flow was lower than with pentobarbitone, and this could be attributed to a smaller bile salt non-dependent fraction of secretion. The effect of bile salts on the maximal excretion of the two organic anions appeared more clearly related to some kind of micelle interaction in rabbits anaesthetized with urethane than in pentobarbitone-anaesthetized animals. Thus, under urethane, infusions of glycodeoxycholate substantially increased the maximal excretion of bilirubin and BSP, taurocholate exerted an intermediate and dehydrocholate only a small effect. Under pentobarbitone, however, the augmenting action of all three bile salts was similar. The influence of bile salts on the endogenous excretion of bile pigments in experiments in which the test anion was BSP showed corresponding differences dependent upon the anaesthetic used. Possible explanations for those results are discussed.

Enhancement of maximal bilirubin excretion by bile salts in the anaesthetized rabbit

The influence of glycodeoxycholate, taurocholate and dehydrocholate on the maximal hepatic excretion of bilirubin was investigated in rabbits anaesthetized with sodium pentobarbitone. Biliary secretion of dehydrocholate was much less than that of the other two bile salts, which could be explained by its metabolism in the hepatocytes. Glycodeoxycholate and dehydrocholate had a greater choleretic effect than taurocholate. Only glycodeoxycholate and taurocholate increased the secretion of biliary lipids, suggesting that dehydrocholate or its metabolites were unable to form micelles. All three bile salts, however, increased maximal bilirubin excretion to a similar extent. These results indicate that the action of bile salts on the excretion of bilirubin cannot be fully explained in terms of binding to mixed micelles.

Effect of sympathetic stimulation on salivary secretion in submandibular gland in the rabbit stimulated by pilocarpine

The sympathetic stimulation under slow pilocarpine-induced flow conditions brought about a decrease in this flow rate that could be due to vasoconstriction, since such an effect was not observed after the administration of phentolamine (4 mg/kg i.v.). Contrariwise the injection of a beta-adrenergic blocking agent (propranolol 2-2.5 mg/kg i.v.) produced a decrease of the salivary flow rate that was even greater than in the control animals. These results suggest that the secretory effect in this gland and species is predominantly beta-adrenergic. The stated results are related to the changes observed in the blood outflow from the gland.

Role of alpha and beta adrenoceptors on the salivary secretion in the mandibular gland of the rabbit

The stimulation of the superior cervical ganglion increased the salivary flow rate (about five-fold) in all 35 rabbits studied but two. The administration of alpha or beta adrenoceptor blocking drugs was unable to eliminate the positive effect of the sympathetic stimulation on the salivary flow, though the flow rate fell about 50% with the administration of each of the blockers. According to these results both types of receptors may be involved in the secretory response of this gland. Nevertheless it seems that the beta-adrenoceptors play a more important role in the secretory response and the alpha-adrenoceptors in the motor one.

Active secretion of bicarbonate by rabbit colon

A serosa-mucosa movement of bicarbonate against concentration gradient was detected at this intestinal level. This movement is partially dependent on oxidative phosphorylation since it is abolished by DNP administration, but as it is not affected by acetazolamide administration it can be supposed as dependent on carbonic anhydrase activity.

Relative changes in bile secretion during rat liver regeneration

The influences of partial hepatectomy (66%) on some aspects of rat biliary secretion were studied at different time intervals after surgery (0, 40, 96, 192 and 384 h). Bile salt independent and bile salt dependent fractions were determined. During the first intervals (40 and 96 h) bile salt independent fraction clearly decreased after which it slowly recovered (192 h) until control levels were reached (384 h). These results are interpreted as proof of a faster compensatory hyperplastic regeneration in zone I of the hepatic acinus than in zone III.