Author:
Rheault Mark R.,Debicki Donna M.,O'Donnell Michael J.
Abstract
Basolateral transport of the prototypical type I organic cation tetraethylammonium (TEA) by the Malpighian tubules of Drosophila melanogaster was studied using measurements of basolateral membrane potential (Vbl) and uptake of [14C]-labeled TEA. TEA uptake was metabolically dependent and saturable (maximal rate of mediated TEA uptake by all potential transport processes, reflecting the total transport capacity of the membrane, 0.87 pmol·tubule−1·min−1; concentration of TEA at 0.5 of the maximal rate of TEA uptake value, 24 μM). TEA uptake in Malpighian tubules was inhibited by a number of type I (e.g., cimetidine, quinine, and TEA) and type II (e.g., verapamil) organic cations and was dependent on Vbl. TEA uptake was reduced in response to conditions that depolarized Vbl(high-K+saline, Na+-free saline, NaCN) and increased in conditions that hyperpolarized Vbl(low-K+saline). Addition of TEA to the saline bathing Malpighian tubules rapidly depolarized the Vbl, indicating that TEA uptake was electrogenic. Blockade of K+channels with Ba2+did not block effects of TEA on Vblor TEA uptake indicating that TEA uptake does not occur through K+channels. This is the first study to provide physiological evidence for an electrogenic carrier-mediated basolateral organic cation transport mechanism in insect Malpighian tubules. Our results also suggest that the mechanism of basolateral TEA uptake by Malpighian tubules is distinct from that found in vertebrate renal tubules.
Publisher
American Physiological Society
Subject
Physiology (medical),Physiology
Reference40 articles.
1. Anomalous Rectification in the Squid Giant Axon Injected with Tetraethylammonium Chloride
2. Ashburner M.Drosophila: A Laboratory Manual. Cold Spring Harbor, NY: Cold Spring Harbor Laboratory Press, 1989.
3. Boom SAP, Gribnau FWJ, and Russel FGM.Organic cation transport and cationic drug interactions in freshly isolated proximal tubular cells of the rat.J Pharmacol Exp Ther263: 445–450, 1992.
4. Brändle Eand Greven J.Transport of Cimetidine across the basolateral membrane of rabbit kidney proximal tubules: characterization of transport mechanisms. J Pharmacol Exp Ther258: 1038–1045, 1991.
5. N1-methylnicotinamide transport by isolated perfused snake proximal renal tubules
Cited by
8 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献