Lacrimal gland flow and potentials during dinitrophenol, ouabain, and ethacrynic acid perfusion

Abstract

Acetylcholine (ACh)-evoked flow from the main excretory duct as well as ACh-induced secretory and resting membrane potentials from cells of the rabbit lacrimal gland were recorded during perfusion with inhibitors. During perfusion with 2,4-dinitrophenol (DNP), ouabain, or ethacrynic acid, ACh-induced flow was 5%, 20%, and 8% of control, respectively; ACh-induced hyperpolarizing secretory potential was 64%, 50%, and 63% of control, respectively; and the resting membrane potential was 79%, 64%, and 73% of control, respectively. Only during perfusion with ethacrynic acid was there a significant increase in the number of cells that did not respond to ACh with a change in potential. We have concluded that (1) ACh-induced secretion is highly dependent on oxidative metabolism and Na-K ATPase; (2) ACh-induced hyperpolarization is dependent on changes in ionic permeabilities, Na-K ATPase, and to lesser extent oxidative metabolism; and (3) the resting membrane potential is much less dependent on oxidative metabolism and Na-K ATPase activity.