Pancreatic Secretion by the Anaesthetized Rabbit in Response to Secretin, Cholecystokinin, and Carbachol

Abstract

Considerable differences exist among species in the patterns of regulation of pancreatic secretion. Although rabbit pancreas is quite often used for in vivo and in vitro studies of pancreatic function, responses of this gland in vivo to common pancreatic stimuli have never been characterised in detail. That was the purpose of this study. The data demonstrate the existence of a spontaneous fluid secretion that can be increased by intravenous infusions of secretion (sevenfold), cholecystokinin-octapeptide (CCK8) (threefold), and carbachol (sixfold). The electrolyte composition of the secretion evoked by each of these stimuli was similar: sodium and potassium concentrations were constant and slightly higher than those in plasma at all secretory rates, whereas bicarbonate concentration rose with secretory rate to approach a plateau of about 125 mmol/L, and chloride concentration fell to a plateau of about 35 mmol/L. In terms of protein secretion, secretin caused a small but significant rise in output, while CCK8 and carbachol evoked the expected large increase. Thus, regulation of pancreatic electrolyte secretion in rabbit differs from that in dog, cat, and human, on the one hand, and rat, on the other hand, and most closely resembles the pattern observed in guinea pig.