¹ From the Cardiovascular Research Institute and the Department of Medicine, University of California School of Medicine, San Francisco.

Dr. Maffly's present address is the Department of Medicine, Stanford University School of Medicine, Palo Alto

The relationship of the short-circuit current to metabolism was studied in the toad bladder in vitro. Substrates and inhibitors were added to the bathing medium and the effect on the short-circuit current was determined. The spontaneous decline in the short-circuit current that occurred in substrate-free media was prevented or reversed by the addition of glucose, pyruvate, lactate, or ß-hydroxybutyrate, whereas acetate and tricarboxylic acid cycle intermediates had no effect. A variety of metabolic inhibitors depressed the short-circuit current; depression by iodoacetate and by malonate was delayed by prior addition of pyruvate or lactate but not by glucose. The ability of a substrate to stimulate the current did not correlate with its rate of oxidation to CO₂. On the basis of earlier studies, the metabolic effects on the short-circuit current were assumed to reflect equivalent effects on the rate of active Na transport. It is suggested that the energy for Na transport is provided not by a general cellular metabolic pool but by a specific metabolic pathway or pathways spatially linked to the transport mechanism.

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

Home | Help | Feedback | Subscriptions | Archive | Search | Table of Contents