Elimination of Porcine Secretin in Pigs

Abstract

1. The elimination of immunoreactive secretin was studied in anaesthetized pigs by using constant infusions of pure natural porcine secretin. 2. The mean metabolic clearance rate was 15.4 ml min-1 kg-1, and was independent of the level at which it was determined. The mean distribution space was 64.4 ml/kg. The half-life of secretin after termination of the infusion averaged 2.6 min. 3. During intravenous infusion of secretin in a dose of 27.8 pmol h-1 kg-1 the renal extraction was 52%. Exclusion of the kidneys increased plasma secretin concentration from 26.5 pmol/l to 47.3 pmol/l and increased the half-life to 4.4 min. 4. Exclusion of the liver during infusion of secretin in a dose of 27.8 pmol h-1 kg-1 resulted in an increment in plasma secretin concentration of 7.8 pmol/l and an increase of the half-life to 3.6 min. 5. A gradient of endogenous secretin across the liver was present but no arteriovenous difference was found across the foreleg. 6. Incubation of secretin with whole blood or serum for 20 min at 37 degrees C did not result in any degradation of secretin.

Secretin Levels in Plasma and Tissue of the Neonatal Swine

“…The current study documents fasting hy persecretinemia in the neonatal swine when compared to the values in the adult animals [8]. These data confirm the findings of Rog ers et al [7] regarding similar elevations in serum secretin levels in human neonates.…”

“…In our present study, the mean half-life of exogenously administered secretin in the newborn swine was estab lished as 3.6 min. which is significantly lon ger when compared to the 2.6 min reported in adult pigs [8] (0.05 > p > 0.02). These data appear to implicate a defective clearance of secretin as contributing to the fasting and stimulated hypersecretinemia in the neonatal swine.…”

“…To ex plore these hypotheses further, an animal model is obviously necessary as ethical con siderations make it a difficult project to un dertake in the human neonate. As the pig is an omnivore and its gastrointestinal physiol ogy is closely related to that of humans, this animal has served successfully as a model to gain insight into the function of the gastroin testinal tract of the human subject [7,8],…”

Endogenous Secretin in the Rat — Evidence for a Role as an Enterogastrone but Failure to Influence Serum Calcium Homeostasis

“…Blood sampling into pre-chilled tubes: after termination of the secretory study animals were anaesthetized (see above), laparotomized, the abdominal aorta punctured and blood drawn, all within 5-8 min and during ongoing id and iv infusion. This was necessary because the plasma half-life of secretin is <3 min (Wittmann, 1983;Fahrenkrug et al, 1978), and in order to sample sufficient blood for determination of hormones, especially secretin (see below). Serum and plasma (1.2 mg EDTA, 500 KIU Aprotinin per ml blood) were stored at 30 oc until analyzed.…”

Effect of renal failure on gastrointestinal hormones

“…The development of a radioimmunoassay for the measurement of secretin in body fluids has helped resolve this problem. In both dogs [19] and pigs [20], the kidney has been shown to account for 45-50% of the catabolism of secretin and, thus, is the major site for secretin breakdown.…”