Characteristics of the Luminal Proton Pump in Malpighian Tubules of the Ant
作者:
S. Dijkstra,
E. Lohrmann,
E. Van Kerkhove,
R. Greger,
期刊:
Kidney and Blood Pressure Research
(Karger Available online 1994)
卷期:
Volume 17,
issue 1
页码: 27-39
ISSN:1420-4096
年代: 1994
DOI:10.1159/000173785
出版商: S. Karger AG
关键词: Malpighian tubule;V-type ATPase;Proton pump;Luminal pH;Bafilomycin;N-Ethylmaleimide;Schering compound;Omeprazole;Vanadate
数据来源: Karger
摘要:
The active pump mechanisms involved in K+ secretion of the malpighian tubules of the ant and present in the luminal membrane were investigated on isolated, luminally perfused tubules of Formica. The specific blocker for vacuolar type ATPases, bafilomycin A1, was found to half-maximally inhibit secretion at a concentration of 10-5 mol/l when added to the lumen. N-Ethylmaleimide reduced the calculated short circuit current (Isc) to 78 and 21% of control value when added at 5 · 10-4 mol/l, respectively, to the lumen and the bath. Reducing luminal pH inhibited Isc with a half-maximal inhibition at a luminal pH of 4.5. Acidified omeprazole, Schering compound 28080 and vanadate (both 10-3 and 10-4 mol/l) inhibited Isc only partially. The present data suggest that the luminal membrane of ant malpighian tubules contains a H+ pump. This pump is only poorly bafilomycin-sensitive. Furthermore, additional active transport systems responsible for secretion may be present. Part of these results have been published as abstracts
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