Electrolyte secretion from rabbit pancreas in vitro

Abstract

A technic has been developed permitting direct collection of undiluted rabbit pancreatic secretion in vitro without vascular perfusion. The rates of secretion and output of electrolytes were comparable to those obtained in situ. When secretin was added, flow and bicarbonate concentration increased. Secretion in vitro ceased when inhibitors of glycolysis and aerobic metabolism were added to the bathing solution. The sodium concentration of the secretion exceeded that of the bathing solution in all but one observation. Potassium concentrations in secretion were linearly related (slope = 0.93) to the potassium concentration in the bath over a range of 5.8–12.0 mm. After 4–5 hr in vitro, the total carbon dioxide concentration of secretion had decreased while chloride concentration increased with no significant change in the rate of secretion. When secretory rate changed over a range of approximately 30–600 µliters/hr, chloride and carbon dioxide output varied directly with the rate of secretion. The osmolarity of the bathing solution and secretion were always equivalent. These results are incompatible with direct plasma filtration and bicarbonate-chloride exchange as the main mechanisms of pancreatic secretion.