Influence of amphotericin, amiloride, ionophores, and 2,4-dinitrophenol on the secretion of the isolated cat's pancreas.

Abstract

The isolated cat pancreas was perfused with a Krebs-Henseleit-solution containing different concentrations of Amphotericin, Amiloride, Gramicidin, Dinitrophenol, Valinomycin, and Nigericin. In order to separate functionally the effects of these substances on the mitochondrial and the plasma membrane, we tested their influence on the secretory flow rate under aerobic and anaerobic conditions. A Na+−K+- and a HCO3 −-ATPase have been found in membrane fractions of pancreatic homogenates. Since there is a possibility that these enzymes are involved in active ion transport, we tested the effect of all substances on the level of activity of both Na+K+-ATPase and HCO3 −-ATPase. The following were found: All tested substances except Gramicidin had an effect on pancreatic electrolyte secretion. Concerning the aerobic experiments, the inhibitory effect of Dinitrophenol and the ionophores might be due to uncoupling of oxidative phosphorylation. The results of the anaerobic experiments are interpreted as being due to changes of cell membrane permeability. As the effects of Nigericin, Valinomycin and Amiloride in the anaerobic experiments correspond to the effects of these substances on the ATPase activity, we suggest that these enzymes might be involved in the active transport processes of NaHCO3 −-secretion.