Pancreatic Bicarbonate Response Research Articles

Pancreatic secretory response to intraileal amino acids: studies in dogs with an in situ neurally isolated ileum.

Intraileal carbohydrates and lipids affect the pancreatic exocrine secretion, but the effect of intraileal amino acids and the role of the extrinsic nerves of the ileum as mediators of the pancreatic bicarbonate and enzyme output are unknown. Four dogs underwent total extrinsic denervation of the entire ileum. Thomas-like cannulas were placed into the stomach, duodenum (to collect pure pancreatic juice), and at the jejuno-ileal junction. Eight neurally intact control dogs received only the three fistulas. After recovery, in both sets of dogs, dose-response studies of the pancreatic secretory response to intraileal infusion with graded loads of tryptophan (0.12-10.0 mmol/h) were performed, given against an intravenous (iv) background of secretin (20.5 pmol/kg/h) and cerulein (29.6 pmol/kg/h). On separate days, control experiments with intraileal infusion of 0.15 M NaCl were performed. In both sets of dogs, iv secretin plus cerulein significantly (p < 0.05) increased pancreatic bicarbonate and protein output above basal. Intraileal tryptophan caused a dose-dependent decrease in the pancreatic bicarbonate and protein response to secretin plus cerulein. In the dogs with denervated ileum, this inhibition was significantly stronger than in the intact animals. In both sets of dogs, the 225-min integrated bicarbonate (IBR) and protein response (IPR) to all loads of tryptophan were significantly lower than in control experiments. Both IBR and IPR were significantly lower in the denervated as compared with the intact animals. 1) Extrinsic denervation of the entire ileum is a valuable preparation to study the role of nerves in the control of pancreatic exocrine secretion; 2) both in the intact and denervated animals the amino acid tryptophan induces an "ileal brake" of the hormonally stimulated pancreatic bicarbonate and protein output; 3) the extrinsic nerves of the ileum are probably not the dominant mediators of the inhibitory action of intraileal tryptophan but rather counteract this effect.

Pancreatic bicarbonate response to intraduodenal tryptophan in dogs: role of muscarinic M1-receptors and cholecystokinin.

In dogs, 1. Activation of cholecystokinin-receptors is needed for an adequate pancreatic bicarbonate response to secretin; 2. Cholinergic nerve fibers ending on M1-receptors are probably of little or no importance for the bicarbonate response to secretin in the given dose; 3. The bicarbonate response to tryptophan, given with a secretin background, is controlled by cholinergic M1-fibers and by cholecystokinin; 4. M1-fibers mainly mediate the bicarbonate response to low loads of tryptophan, whereas cholecystokinin controls the response to low and high loads of tryptophan; and 5. Both mediators interact in a synergistic manner. In six conscious dogs with chronic gastric and duodenal fistulas, we compared the action of the M1-receptor antagonist telenzepine (20.25-81.0 nmol/kg/h), the cholecystokinin-receptor antagonist L-364,718 (0.025-0.1 mg/kg/h), and combinations of both on the pancreatic bicarbonate response to graded loads of intraduodenal tryptophan (0.37-10.0 mmol/h), given against a background of secretin (20.5 pmol/kg/h). Secretin significantly (p < 0.05) stimulated the pancreatic bicarbonate output above basal levels. All doses of L-374,718, but not telenzepine, significantly decreased the bicarbonate response to secretin by up to 64%. Additional administration of telenzepine together with L-364,718 had no further inhibitory effect on the secretin-stimulated bicarbonate output as compared to L-364,718 given alone. All loads of tryptophan significantly increased the bicarbonate output over that seen with secretin alone (= incremental bicarbonate response to tryptophan). Telenzepine significantly decreased the incremental bicarbonate response to the two lower loads (0.37-1.1 mmol/h) of tryptophan (by 82-124%); L-364,718 decreased the incremental bicarbonate response to all loads of tryptophan (by 50-118%). The incremental bicarbonate output, as well as the 180-min integrated bicarbonate response to all loads of tryptophan, were abolished by all combinations of both antagonists.

The effect of pancreatic denervation and atropine on the cholecystokinin-induced pancreatic exocrine response.

To study the influence of extrapancreatic neural and cholinergic activity on the pancreatic response to cholecystokinin (CCK), six dogs underwent creation of Herrera pancreatic fistulas, placement of Thomas gastric cannulas, and distal pancreatectomies (innervated; INN). Six additional dogs were prepared similarly, with the addition of total extrinsic pancreatic denervation (denervated; DEN). The pancreatic protein and bicarbonate response to graded 12.5 to 200 ng/kg/h CCK doses was determined for INN and DEN animals both alone and with 10 micrograms/kg/h atropine infusion. The influence of extra-pancreatic neural and cholinergic activity on secretin's potentiation of the CCK-induced pancreatic response was then determined by repeating the studies with a 125 ng/kg/h secretin infusion. The latter results were compared to those predicted by summating the responses seen during separate 12.5-200 ng/kg/h CCK dose-response and 125 ng/kg/h secretin studies. Unstimulated protein output was diminished by atropine in INN animals (78 +/- 21 vs. 39 +/- 9 mg/15 min; p < 0.05) but not in DEN animals. Unstimulated bicarbonate outputs, integrated bicarbonate and protein outputs, and bicarbonate and protein dose-response curves were unaffected by denervation or atropine. Potentiation of CCK-induced bicarbonate output by secretin was also unaffected by atropine and denervation. We conclude that cholinergic elements are involved in unstimulated, but not CCK-induced, enzyme secretion. Further, potentiation of CCK-induced bicarbonate output by secretin does not depend on extrinsic neural or cholinergic elements.

Pituitary adenylate cyclase-activating polypeptide (PACAP) stimulates exocrine pancreas in conscious preruminating calves

The effects of new hypothalamic peptides, PACAP-27 and PACAP-38, and secretin and VIP on the interdigestive pancreatic secretion and duodenal myoelectric activity during the asecretory phase of the pancreatic interdigestive cycle, compared with the milk ingestion phase, were examined in five calves. Peptides were infused for 5 min into the external jugular vein (0, 3, 10, 30 and 100 pmol/kg body wt during the asecretory phase of the pancreatic interdigestive cycle, and the pancreatic secretory response was compared with that obtained during milk ingestion. Intravenous infusion of PACAP-27 caused dose-related stimulation of pancreatic juice flow and bicarbonate and protein output; this effect was identical to infusion of secretin. The effect of PACAP-38 was less pronounced, and that of VIP was the weakest. Pancreatic juice volume and bicarbonate responses during milk ingestion were similar to responses obtained with the highest doses of hypothalamic peptides and secretin, whereas postprandial protein secretion was much greater than the secretion stimulated with peptides. It was concluded that PACAP from the VIP/secretin family may stimulate pancreatic exocrine secretion in conscious calves and a part of the pancreatic response to food intake can be mediated by PACAP.

Pituitary adenylate cyclase-activating polypeptide (PACAP) stimulates exocrine pancreas in conscious preruminating calves

The effects of new hypothalamic peptides, PACAP-27 and PACAP-38, and secretin and VIP on the interdigestive pancreatic secretion and duodenal myoelectric activity during the asecretory phase of the pancreatic interdigestive cycle, compared with the milk ingestion phase, were examined in five calves. Peptides were infused for 5 min into the external jugular vein (0, 3, 10, 30 and 100 pmol/kg body wt during the asecretory phase of the pancreatic interdigestive cycle, and the pancreatic secretory response was compared with that obtained during milk ingestion. Intravenous infusion of PACAP-27 caused dose-related stimulation of pancreatic juice flow and bicarbonate and protein output; this effect was identical to infusion of secretin. The effect of PACAP-38 was less pronounced, and that of VIP was the weakest. Pancreatic juice volume and bicarbonate responses during milk ingestion were similar to responses obtained with the highest doses of hypothalamic peptides and secretin, whereas postprandial protein secretion was much greater than the secretion stimulated with peptides. It was concluded that PACAP from the VIP/secretin family may stimulate pancreatic exocrine secretion in conscious calves and a part of the pancreatic response to food intake can be mediated by PACAP.

The Inhibitory Effect of Octreotide on Exocrine Pancreatic Secretion in Conscious Dogs

The effects of somatostatin and its analogue, octreotide (SMS201-995), on pancreatic secretion and gastroduodenal motility in response to secretin and cholecystokinin octapeptide (CCK-8) were studied in five conscious dogs. Intravenous infusions of octreotide or somatostatin (1 nmol kg-1 h-1) inhibited periodic pancreatic secretion and the potentiation of fluid and bicarbonate responses to secretin at 60 ng kg-1 h-1 associated with the interdigestive gastroduodenal motility peaks (migrating motor complex). Pancreatic fluid and bicarbonate responses to secretin (125-1,000 ng kg-1 h-1) were not inhibited by octreotide or somatostatin. Pancreatic protein and enzyme responses to secretin and CCK-8 at 50 and 100, but not at 200 and 400, ng kg-1 h-1 were inhibited by octreotide and somatostatin. These inhibitory effects were similar to those of atropine (25 micrograms kg-1 h-1). The inhibition of protein responses to CCK-8 (100 ng kg-1 h-1) was dependent on octreotide dose. It is concluded that both octreotide and somatostatin, like atropine, inhibit interdigestive pancreatic secretion and the responses to small, but not large, doses of secretin and CCK-8 in conscious dogs.

Hormonal Control of Pancreatic Secretion by Intrajejunal HCl

To elucidate the role of hormones in the control of pancreatic secretion, we developed, in seven dogs, a model of total extrinsic denervation of the jejunoileum by autotransplanting this segment of bowel. A Thomas-like cannula was placed into the stomach, the duodenum (to collect pure pancreatic juice), and the proximal part of the jejunum. Thus, intestinal stimulants could only stimulate the pancreas via release of humoral (= hormonal) mediators. Seven control dogs received only the three fistulas. After recovery, dose-response curves of pancreatic bicarbonate and protein response to perfusion of the extrinsically denervated or innervated jejunoileum with HCl (1.5 to 48 mmol h-1) were performed with and without atropine (14 nmol kg-1 h-1 i.v.). Plasma levels of secretin were determined by radioimmunoassay. The maximal bicarbonate output occurred in response to 24 mmol h-1 of HCl and was significantly (p less than 0.05) higher in intact as compared to denervated animals. Atropine only significantly depressed the bicarbonate response to HCl in dogs with a denervated jejunoileum. HCl caused a dose-dependent increase in plasma levels of secretin, which was not altered by denervation and/or atropine. Irrespective of the innervation of the small bowel, pancreatic protein output was only significantly stimulated above basal when high loads (12-48 mmol h-1) of HCl were given. Atropine significantly reduced these responses.(ABSTRACT TRUNCATED AT 250 WORDS)

Pancreatic Secretory Responses to Long-Term Infusions of Secretin and Cerulein in Humans

We measured pancreatic enzyme and bicarbonate responses to graded doses of intravenous secretin or cerulein alone or together in healthy human subjects. Bicarbonate responses were steady and well maintained during the last 3.5 h of the 4 h of infusions of secretagogues, giving evidence for a constant pancreatic flow rate. Potentiation (more-than-additive response) was observed between secretin and cerulein for bicarbonate secretion, but not for enzyme secretion. Secretin stimulated pancreatic enzyme secretion. The effect was most pronounced with amylase secretion and less prominent with lipase, trypsin, and chymotrypsin secretion. Changes in the proportion of enzymes were seen over time, with trypsin and chymotrypsin output declining towards the end of cerulein infusion. We conclude that in humans the effects of secretin on pancreatic enzyme secretion are complex and include time-dependent changes in the enzyme mixture, but potentiation between secretin and cerulein does not occur for enzyme output.

Geranyl-Geranyl Acetone

Geranyl-geranyl acetone (GGA), a new acyclic polyisoprenoid, anti-ulcer drug appears to exert its beneficial effect by stimulating bicarbonate secretion from the stomach and pancreas. Its efficacy in stimulating pancreatic bicarbonate is particularly striking, and this study was designed to examine the mechanism for this action. Since it is structurally similar to the side chain of the prostaglandin molecule, its ability to stimulate bicarbonate secretion could be a direct one. On the other hand, the magnitude of pancreatic bicarbonate response (about 50% of maximal response to secretin) suggests it might act by releasing secretin. Two types of experiments were performed in dogs with pancreatic fistulas: first, secretagogue interactions were examined by studying the effect of intraduodenal GGA (8 mg/kg) or its carrier (control) on the dose-response curves to exogenous secretin and cholecystokinin octapeptide (CCK-8); second, the effect of graded doses of intraduodenal GGA on pancreatic bicarbonate and plasma secretin-like immunoreactivity (SLI) responses was tested directly. Pancreatic bicarbonate responses (micromoles per 30 min) were to secretin doses of 32, 125, and 500 ng/kg/h. Without and with GGA, responses were 74 +/- 27, 952 +/- 215, and 2,000 +/- 425 and 599 +/- 110, 1,624 +/- 472, and 2,129 +/- 398 ng/kg/h, respectively. Similarly, the bicarbonate responses to CCK-8 were augmented. Basal plasma SLI was 1.5 +/- 0.6 pM/ml. Peak plasma SLI in response to 2, 4, and 8 mg of GGA intraduodenally were 6.8 +/- 0.7, 8.9 +/- 3.1, and 19.6 +/- 2.7 pM/ml, respectively. It is concluded that GGA is a potent stimulant of pancreatic bicarbonate secretion, and this action appears to be mediated by the release of duodenal secretin.

Pancreatic bicarbonate response to HCl before and after cutting the extrinsic nerves of the pancreas in dogs.

In two sets of dogs with gastric and pancreatic fistulas, we studied the effect of atropine on pancreatic bicarbonate output and release of secretin in response to intraduodenal HCl before and after stepwise removal of the extrinsic nerves of the pancreas, i.e., celiac and superior mesenteric ganglionectomy alone or truncal vagotomy alone and truncal vagotomy plus celiac and superior mesenteric ganglionectomy. Ganglionectomy alone did not alter the incremental bicarbonate response to HCl. Truncal vagotomy alone significantly (P less than 0.05) decreased the incremental bicarbonate response to low (1.5 and 3 mmol/h) but not high (6 to 24 mmol/h) loads of HCl. Additional ganglionectomy restored the bicarbonate response to prevagotomy levels. With the extrinsic nerves intact and after ganglionectomy, but not after truncal vagotomy and truncal vagotomy plus ganglionectomy, intravenous atropine (14 nmol.kg-1.h-1) significantly reduced the incremental bicarbonate response to low (1.5 and 3 mmol/h) but not high loads of HCl. Neither the different surgical procedures nor atropine significantly altered plasma levels of secretin basally and in response to intestinal HCl. We conclude that 1) cholinergic fibers within the vagus nerves but not the splanchnic nerves are important mediators of the pancreatic bicarbonate response to low loads of HCl and 2) release of secretin by intestinal HCl is not under cholinergic and splanchnic control.

Subtypes of muscarinic receptors in canine pancreatic secretion in vivo and in vitro

In conscious dogs with esophageal, gastric and pancreatic fistulae, sham-feeding and meat feeding increased the pancreatic protein secretion to a peak, reaching about 39% and 69% of CCK8 maximum, and raised plasma pancreatic polypeptide (PP) levels. Pirenzepine given intravenously (i.v.) (30 nmol.kg-1 or 3 mumol.kg-1) reduced dose-dependently the pancreatic protein and plasma PP responses to sham-feeding and meat feeding, being about 100 times less potent as an inhibitor than atropine. Neither pirenzepine nor atropine affected near-maximal pancreatic bicarbonate and protein responses to secretin (164 pmol.kg-1.h-1) and CCK8 (170 pmol.kg-1.h-1), but both antimuscarinic agents significantly inhibited pancreatic responses to lower doses of these secretagogues. When added to the incubation medium of dispersed canine pancreatic acini, pirenzepine reduced dose-dependently the amylase responses only to urecholine, and not to CCK or gastrin, being about 1000 times less potent as an inhibitor than atropine. This report provides an evidence that pirenzepine inhibits pancreatic secretion in a similar manner to atropine, but that pirenzepine, in both in vivo and in vitro studies, is 2-3 orders of magnitude less potent as an inhibitor than atropine, indicating that the muscarinic pathway of the exocrine pancreas has a low affinity for pirenzepine and may thus involve M2-receptors.

Dose-response effects of atropine on pancreatic secretory response to intestinal tryptophan in dogs.

In dogs with gastric and pancreatic fistulas, we studied the effect of intravenous infusion of atropine in doses of 0.9, 1.8, 7, and 29 nmol X kg-1 X h-1 on the pancreatic secretory response to graded loads of intraduodenal infusions of tryptophan, given with a secretin background. Infusions of 1.8, 7, and 29, but not 0.9 nmol X kg-1 X h-1 of atropine sulfate significantly (P less than 0.05) decreased the incremental protein response to all loads of tryptophan. The cumulative incremental protein output was reduced by 44, 37, and 52%, respectively. Infusions of 1.8, 7, and 29 nmol X kg-1 X h-1 of atropine significantly decreased by approximately 50% the incremental bicarbonate response to low (0.12 and 0.37 mmol/h) but not high loads (1.1, 3.3, and 10 mmol/h) of tryptophan. The inhibitory potency of the effective doses of atropine did not differ significantly. Only the highest dose of atropine significantly increased heart rate by 76%. These findings indicate that 1) in the intact animal, the minimal dose of atropine required for inhibition of pancreatic bicarbonate and protein response to intraduodenal tryptophan seems to be 1.8 nmol X kg-1 X h-1, a dose that causes probably few systemic effects, since it does not increase heart rate; and 2) the inhibitory action of atropine on the pancreatic response to tryptophan appears to be an "all-or-none" effect.

Action of atropine on the pancreatic secretory response to secretin before and after cutting the extrinsic nerves of the pancreas in dogs

In two sets of dogs with gastric and pancreatic fistulas, we studied the effect of atropine on the pancreatic secretory response to intravenous secretin before and after cutting the extrinsic nerves of the pancreas, i.e., celiac and superior mesenteric ganglionectomy alone or truncal vagotomy plus celiac and superior mesenteric ganglionectomy. Neither truncal vagotomy alone nor ganglionectomy alone, nor the two together, altered the incremental bicarbonate response to secretin. Irrespective of the degree of integrity of the extrinsic vagal and splanchnic innervation of the pancreas, intravenous atropine (14 nmol/kg · h) significantly (p < 0.05) depressed the incremental bicarbonate responses to the two lowest (5.2 and 10.3 pmol/kg · h) doses of secretin by 85% and 61%, respectively, but had no significant effect on responses to high doses. We conclude that the pancreatic bicarbonate response to secretin, and the action of atropine on that response, are independent of an intact extrinsic innervation of the gland. The observation of the persistent inhibitory action of atropine after extrinsic denervation of the pancreas is compatible with the hypothesis that endogenous cholinergic activity augments the pancreatic bicarbonate response to secretin.

Characteristics of secretin-stimulated pancreatic secretion in dogs.

The effect of the periodic interdigestive activity of the gut on secretin-stimulated pancreatic secretion was studied in eight conscious dogs each with a Thomas duodenal fistula, a gastric fistula and a Heidenhain pouch. Pancreatic water and bicarbonate responses to a small dose of secretin were greatly augmented in phase with the spontaneous periodic activity of the gut. This augmentation was closely related to pancreatic protein secretion. As the dose of secretin was increased the interval between peaks was prolonged, the peaks became less sharp, the nadirs were raised, and finally the periodic activity was no longer seen. Bilateral cervical vagal blockade with local anaesthetics reduced the secretin-stimulated bicarbonate secretion by 50% but the augmentation at the peak was not abolished. Atropine abolished the periodic augmentation completely and reduced the bicarbonate response by 80%. The peak response of volume and bicarbonate to secretin obeyed Michaelis-Menten kinetics. The nadir secretin dose response, however, was a sigmoid curve with a Hill coefficient larger than one. The action of atropine or hexamethonium was to shift the peak response kinetics to the nadir kinetics. It is concluded that the pancreatic response to secretin is greatly modulated by the spontaneous periodic activity of nerves.

Pancreatic bicarbonate response to food-bound hydrogen ion along the gut

Recent reports suggest most solid food enters the duodenum as small particles. Our studies showed that small particles of liver were capable of binding hydrogen ions (H+), but there was slow equilibration of H+ between particulate and aqueous phases. We wondered whether titratable acid as H+ bound to meat particles could effectively stimulate pancreatic bicarbonate secretion despite slow diffusion. We studied mongrel dogs with chronic pancreatic fistulas; the intestinal lumen was washed free of endogenous pancreatic enzymes. Pancreatic bicarbonate and protein responses were measured during duodenal perfusion with pH 2 or pH 3 gels that delivered 1, 2, or 4 mEq/15 min of titratable acid (endpoint pH 4.5). Gels consisted of acidified, 0.1–0.7-mm particles of beef liver or bovine serum albumin or lactic acid suspended with 2% starch in 0.15 M NaCl. The liver, bovine serum albumin, and lactate had similar titration curves. At pH 2 or pH 3, liver particles were about as effective as bovine serum albumin in stimulating pancreatic bicarbonate secretion. Likewise, pH 3 liver particles were equipotent with pH 3 lactate on pancreatic bicarbonate secretion when both perfusates were allowed access to the whole intestine. However, when confined to the first 45 cm of proximal intestine, much less H+ was dissipated from the liver versus the lactate; and, correspondingly, there was a much greater decrement in pancreatic bicarbonate secretion from whole gut responses with liver versus lactate. We conclude that titratable acid bound to solid food particles is a potent stimulus of pancreatic bicarbonate secretion despite its slow diffusion. Our studies suggest that H+ slowly diffusing from particles excites pancreatic bicarbonate secretion by triggering H+ receptors along more distal intestine.

Plasma secretin and pancreatic response to various stimulants including a meal.

In dogs with gastric and duodenal Thomas cannulas, we investigated the threshold dose range of exogenous secretin and intraduodenal HCl for pancreatic bicarbonate secretion and, with a recently developed radioimmunoassay, measured the increase in plasma secretin concentrations. Synthetic secretin (2.5, 7.5, and 22.5 ng X kg-1 X h-1) was dissolved in saline or 0.1% dog albumin and given with or without a background infusion of 30 ng X kg-1 X h-1 of caerulein. The minimal dose of secretin that elicited a significant pancreatic bicarbonate response as well as an increase in plasma secretin concentration was 7.5 ng X kg-1 X h-1 when administered with albumin and 22.5 ng X kg-1 X h-1 without albumin. The threshold dose for duodenal HCl was 2 mmol X h-1. The threshold secretin dose for bicarbonate secretion and for an increase in plasma secretin levels was unchanged with a background caerulein infusion. Furthermore, postprandial secretin concentrations were measured. After a meat meal plasma secretin release appeared to occur in spikes up to 10 pmol X l-1 corresponding to secretin levels seen during infusion of 7.5 ng X kg-1 X h-1 of secretin and intraduodenal acid perfusion at a dose of 2 mmol X h-1.

Does basal cholinergic activity potentiate exogenous secretin for stimulation of pancreatic bicarbonate output in dogs?

In conscious dogs with gastric and pancreatic Thomas fistulas, we studied the effect of atropine sulfate (20 micrograms kg-1 h-1 intravenously) on bicarbonate output basally and in response to intravenous infusion of synthetic secretin (62.5, 125, 250, 500, 1,000 and 2,000 ng kg-1 h-1). We analyzed the data in an attempt to determine whether basal cholinergic activity potentiates the pancreatic bicarbonate response to secretin. Assuming that atropine suppresses all basal cholinergic activity, C (= bicarbonate response to basal cholinergic activity alone) was calculated by subtracting basal pancreatic bicarbonate output with atropine from that without atropine, S (= response to secretin alone) was calculated by subtracting basal pancreatic bicarbonate output with atropine from that in response to secretin with atropine. SwC was defined as the response to secretin acting simultaneously with (w) basal cholinergic activity and was calculated by subtracting basal pancreatic bicarbonate output with atropine from the response to secretin without atropine. If SwC was significantly greater than S + C (= sum of effects of stimulus alone and basal cholinergic activity alone) potentiation between basal cholinergic activity and secretin was assumed to exist. C was 30 +/- 9 mumol 15 min-1 for bicarbonate output. SwC of bicarbonate output was significantly (p less than 0.05) greater than S + C in response to the four lowest doses (62.5-500 ng kg-1 h-1) of secretin. We conclude that potentiation exists between basal cholinergic activity and low doses of exogenous secretin. Thus, basal cholinergic activity is an important modulator of pancreatic bicarbonate response to secretin.

Effect of atropine on pancreatic response to HCl and secretin.

In dogs with gastric and pancreatic fistulas, we studied the effect of atropine on the pancreatic secretory response to secretin and intestinal HCl. Atropine sulfate (20 micrograms.kg-1.h-1 iv) significantly depressed basal bicarbonate and protein output. Atropine depressed bicarbonate responses to low doses (62.5, 125, 250, and 500 ng.kg-1.h-1) of secretin but had no significant effect on responses to high doses (1,000 and 2,000 ng.kg-1.h-1). Secretin, with or without atropine, did not stimulate pancreatic protein output above basal. Atropine depressed bicarbonate responses to low loads (3, 6, and 12 mmol.h-1) of HCl but had no significant effect on responses to high loads (12, 24, and 48 mmol.h-1). Intraduodenal HCl produced a dose-dependent increase in protein output. Atropine abolished protein responses to low loads (3 and 6 mmol.h-1) but did not affect responses to high loads (24 and 48 mmol.h-1) of HCl. These findings are compatible with the hypotheses that a) endogenous cholinergic activity augments the pancreatic bicarbonate response to secretin, and b) the pancreatic protein response to intraduodenal HCl is, at least in part, mediated cholinergically.

Low sweat electrolytes in a patient with cystic fibrosis

A patient with the clinical syndrome of cystic fibrosis characterized by chronic pulmonary disease, infection with mucoid Pseudomonas aeruginosa, sinusitis, nasal polyposis, abnormal pancreatic bicarbonate response to secretin stimulation, but normal levels of trypsin and chymotrypsin in the duodenal drainage, and a sibling with autopsy-documented cystic fibrosis, is described. Sweat chloride ranged from 20 to 44 meq/liter and sweat sodium from 36 to 55 meq/liter. Immunoglobulin deficiency, α 1-antitrypsin deficiency, tuberculosis and abnormalities of ciliary ultrastructure were excluded. Review of sweat electrolytes in 213 patients with cystic fibrosis revealed that patients with normal pancreatic enzyme release have significantly lower sweat sodium and chloride concentrations (p <0.0005) than do patients with pancreatic insufficiency. Chronic pulmonary disease, pancreatic insufficiency and elevated levels of sweat electrolytes comprise the classic diagnostic triad for cystic fibrosis. The expression of these features may be variable, but the sweat test remains the cardinal laboratory confirmation of the diagnosis. Over 98 percent of patients with cystic fibrosis have sweat chloride values greater than 60 meq/liter, 1 to 2 percent between 50 and 60 meq/liter, and only about one in 1,000, like our patient, less than 50 meq/liter. Patients with cystic fibrosis with borderline sweat chloride values frequently have chronic pulmonary disease but intact pancreatic enzyme release. In such patients, family history, ancillary clinical features and systematic exclusion of other syndromes assume special diagnostic importance.

Serum and pancreatic juice carcinoembryonic antigen in pancreatic and biliary disease.

Serum and pancreatic juice carcinoembryonic antigen (CEA) concentrations were studied in a group of 144 patients undergoing endoscopic retrograde cholangiopancreatography (ERCP) with a variety of benign and malignant pancreatic and biliary diseases. Serum CEA was found to be a poor diagnostic and discriminating marker for pancreatic disorders and was raised in obstructive jaundice from various causes correlating with serum alkaline phosphatase. A pancreatic juice CEA concentration of greater than 106 mcg/l was associated with pancreatic disease but did not distinguish benign from malignant lesions. Criteria derived from pancreatic juice volumes and bicarbonate responses provided additional diagnostic differentiation of normal from pancreatic disease but not cancer from pancreatitis. Pancreatic juice CEA may have a limited application where imaging techniques have failed or are not available and additional study of pancreatic juice biochemistry is required before adequate diagnostic criteria can be established.