Disappearance half-time of endogenous and exogenous secretin in dogs.

Abstract

SUMMARY We have used a sensitive and specific radioimmunoassay to measure the disappearance half-times of exogenous porcine secretin and endogenous canine secretin in the dog and found them to be 2-45 and 2-85 minutes, respectively.Since the discovery of secretin in 1902 by Bayliss and Starling, quantitative estimations of secretin activity have been based on the ability of the hormone to stimulate flow of bicarbonate-rich pancreatic juice. Since about the time of the initial isolation of the hormone from hog intestine by Jorpes and Mutt (1959), there have been refinements in bioassay technique (Ivy and Janecek, 1959;Mutt and Soderberg, 1959;Heatley, 1968) which have produced considerable standardisation of results. Unfortunately, these techniques lacked specificity and precision, and were incapable of measuring basal levels of secretin in the circulating plasma of animals and man.Calculations of the disappearance half-time (TI) of secretin were, however, made in laboratory animals using pancreatic secretion as an index of secretin activity (Clark et al., 1967;Lehnert et al., 1969;Hubel, 1972).We have recently validated a radioimmunoassay which is both sensitive and specific and can accurately measure concentrations of secretin of less than 20 pg/mi in plasma (Rayford et al., 1976).Using this assay technique, we have measured plasma levels of secretin in dogs after an infusion of pure natural porcine hormone and have calculated its disappearance half-time. We have also measured basal and stimulated levels of endogenous secretin in dogs and have calculated its disappearance halftime. proximately 20 kg were placed in Pavlov stands and an intravenous catheter placed in a foreleg and a hind leg of each dog. After collecting two 5 ml basal blood samples, 10 minutes apart, each dog received an infusion of pure natural secretin (Professor V.Mutt, Gastrointestinal Hormone Laboratory [GIH], Karolinska Institute, Stockholm), 1.5 unit/kg body weight, dissolved in 50 ml 0-9 % NaCI. This secretin preparation contains 3500 clinical units/mg. The infusion was delivered over 30 minutes into a foreleg vein using a Harvard syringe pump. Blood samples were collected from the hind leg catheter at five-minute intervals during the infusion. The infusion was then terminated and samples collected at one-minute intervals for 10 minutes, then at two-minute intervals for 10 minutes. DISAPPEARANCE HALF-TIME OF ENDOGENOUS SECRETINA further six fasting, adult, mongrel dogs were anaesthetized with intravenous sodium pentobarbital ,(25,mg/kg), and the abdomen opened. A segment of bowel, comprising the whole of the duodenum and the proximal 50 cm of the jejunum, was prepared for stimulation of secretin release by ligation of the pylorus, ligation of the superior pancreaticoduodenal vein at its entry into the portal vein, and division of the jejunum and its mesentery 50 cm distal to the ligament of Treitz. A cannula was introduced into the proximal duodenum for infusion of acid, and the distal end of the segment of bowel was left open to allow f...

Elimination of Porcine Secretin in Pigs

“…The mean half-life of 2-6 min in anaesthetized pigs found in our experiments is in agreement with the results of Boden, Essa, Owen & Reichle (1974) (i 0lJ = 2-8 min) and Curtis, Fender, Rayford & Thompson (1976) (i 0 . 5 = 2-45 min) for infused secretin in anaesthetized dogs, and of Kolts & McGuigan (1977) (i 0 .…”

Secretin-Activated Brown Fat Mediates Prandial Thermogenesis to Induce Satiation

“…To test this hypothesis, fasted mice were injected with 5 nmol secretin before refeeding. Secretin reduced food intake compared with PBS-injected mice ( Figure 3C) during the first 2-3 hr of refeeding, possibly due to the short half-life of secretin (Curtis et al, 1976).…”

Catabolism of gastrin and secretin

“…We conclude that extraction of gastrin and secretin occurs on transit of all capillary beds and appears to be a nonspecific process. Gastrin and secretin, in common with other peptide hormones, have a short disappearance half-time from the circulation as measured by radioimmunoassay [1][2][3][4][5][6]. We and others have shown that both endogenous and exogenous gastrin are inactivated by the kidney [4,[7][8][9][10][11][12].…”