Gastrointestinal hormones.

Much has been learned about the nature, localization, and biological actions of a wide assortment of peptides present in the gastrointestinal tract. Measurement of some of these peptides has been made possible by development of immunoassay techniques. In some instances, ample information has been gained about the roles of these gastrointestinal peptides in physiological events and in pathophysiological states.

Gastrin content of columnar mucosal lining the lower (Barrett's) esophagus.

Tissue gastrin was determined in 36 biopsies obtained from the esophagus and 35 biopsies from the stomach in 12 patients with Barrett's esophagus. Histology of the mucosa from the area adjacent to the biopsy sites was also examined. Esophageal biopsies were obtained from three different sites in each patient.

A study of antibody production for the radioimmunoassay of gastrin.

Gastrin conjugated to bovine serum albumin was administered to New Zealand white rabbits by repeated injections at a standard immunizing dose of 2 mg BSA-gastrin conjugate, as well as at 0.2 mg (10%) and 0.02 (1%) of BSA-gastrin conjugate.

The gastrin-producing cells in tissue cultures of the rat pyloric antrum.

Tissue culture methods were used to study the gastrin-producing cells isolated from the pyloric antral mucosa of rats. Cultures were maintained for up to 7 days. Gastrin cells were identified by means of immunofluorescent and unlabeled antibody-enzyme techniques.

Serum gastrin in health and disease.

Recent developments have led to a further appreciation of the various species of circulating gastrin and to provocative tests for the presence of the Zollinger-Ellison syndrome. Studies of serum gastrin levels, together with other studies of physiologic response, have suggested some possible roles of gastrin in the complex gastric acid hypersecretory state that frequently accompanies duodenal ulcer. Finally, investigations of exogenous and endogenous serum gastrin have provided a mechanism to examine the possible physiologic effects of this hormone.

Stimulation of gastrin secretion and synthesis in antral organ culture.

The purpose of the present study was to examine stimulation of gastrin release and the synthesis of gastrin directly by measurement of incorporation of [(3)H]tryptophan into gastrin in rat antral mucosal explants maintained in organ culture. Gastrin synthesis and secretion were assessed simultaneously at intervals over the 24-h duration of explant culture. Antral mucosal explants from fed female Wistar rats (4-5 wk, 100-150 g) were cultured at 37 degrees C (95% O(2)/5% CO(2)) in medium containing 70% Trowell-T8 and 10% NCTC-135 without unlabeled tryptophan, 10% dialyzed fetal calf serum and [(3)H]tryptophan (100 muCi/ml).

Radioimmunoassay measurement of secretin half-life in man.

High titer antibodies to secretin were produced in rabbits by immunization with purified porcine secretin (from GIH) conjugated to bovine serum albumin in complete Freund's adjuvant. Synthetic porcine secretin (from Squibb) was radiolabeled with 125I using chloramine-T and radiosecretin was purified using talc-silica and fibrocellulose powder. Specificity of antibodies to secretin was extensively evaluated in studies examining (1) cross-reactivity with other naturally occurring hormones, (2) parellelism of serum dilutions and secretin standards, (3) quantitative recovery of secretin added to serum samples, and (4) changes in circulating immunoreactive secretin in response to intraduodenal acidification.

Relationship between internal calcium and outward current in mammalian ventricular muscle; a mechanism for the control of the action potential duration?

In sheep and calf ventricular bundles, increasing the internal calcium by increasing the frequency of voltage-clamping to plateau range potentials increased the time-independent outward current. This effect was more marked with higher [Ca]o, and was reduced if the Ca current blockers Verapamil or D 600 were used. 2.

Lower esophageal sphincter pressures and serum gastrin levels after cholinergic stimulation.

To define the role of gastrin, if any, in the response of the lower esophageal sphincter (LES) to bethanechol, serum gastrin determinations and LES pressure measurements were made in controls, patients with vagotomy and antrectomy (V&A), and patients with vagotomy and pyloroplasty (V&P). Despite significant differences in mean basal serum gastrin levels no differences were found in mean resting LES pressures among these groups. In controls significant increases in LES pressure occurred after subcutaneous bethanechol, but serum gastrin levels did not change from basal values.

Lower esophageal sphincter and gastric acid response to intravenous infusions of synthetic human gastrin I heptadecapeptide.

Human gastrin I heptadecapeptide was administered by constant intravenous infusion to 7 adult male volunteers without gastrointestinal disease, and serum gastrin concentrations and responses of the lower esophageal sphincter (LES) pressure and gastric acid output were measured and compared. Significant responses in LES pressure were found at gastrin infusion rates which produced submaximal gastric acid output. These LES pressure responses were quantitatively smaller than those occurring concomitantly with similar total immunoreactive gastrin levels evoked by administration of a protein meal in the same subjects.

Gastrin in the perinatal rat pancreas and gastric antrum: immunofluorescence localization of pancreatic gastrin cells and gastrin secretion in monolayer cell cultures.

The presence and development of immunoreactive gastrin (IRGa) in the fetal and neonatal pancreas and pyloric antrum of the rat were studied. IRGa appeared in both organs at least as early as the 16th day of fetal life. Antral IRGa increased rapidly and continuously in the neonatal period, while pancreatic IRGa concentration increased and was maintained at a relatively constant level from days 5 to 35.

Degradation of gastrin by gastric mucosal cells.

Specific binding of radiolabeled gastrin by gastric mucosal cells prepared from guinea pigs was detected and examined. Specific cell binding of gastrin was found to be both pH and temperature dependent. Maximum binding of radiolabeled gastrin by gastric mucosal cells was demonstrated at pH 7.

Is gastrin a major determinant of basal lower esophageal sphincter pressure? A double-blind controlled study using high titer gastrin antiserum.

Studies were performed in anesthetized opossums to determine the influence of binding of circulating gastrin with a high titer gastrin antiserum on lower esophageal sphincter pressure. Gastrin antiserum or control antiserum was administered intravenously in successive doses of 0.02, 0.

Gastrin and gastric surgery.

The development of the radioimmunoassay for gastrin has resulted in significant increases in our knowledge of the physiology of the stomach and antrum, and in an objective recognition of the interaction of the gastrin and vagus mechanisms. Recent identification of multiple species of gastrin in the circulation, however, raises questions as to the significance of early experimental results. Until the various aspects of gastrin and their relative contributions in the normal state and in pathologic processes are identified, the significance of gastrin levels in the evaluation of patients with uncomplicated ulcer disease is unclear.