Effects of A-23187 and verapamil on the active transport enzymes in turtle bladder epithelial cells

The American Journal of Physiology
S Sabatini

Abstract

These experiments were designed to examine the effects of A-23187 (5 x 10(-4) M) and verapamil (100 microM) on membrane transport, 45Ca fluxes, and adenosine-triphosphatase (ATPase) activities in turtle bladder. In the intact membrane, the calcium ionophore decreased proton secretion and sodium transport [short-circuit current (SCC)] to approximately the same degree (by approximately 55% at 30 min). During the same period of time, verapamil decreased SCC (by approximately 58%), but proton secretion was unaffected. The turtle bladder membrane is composed predominantly of two cell types: 1) the mitochondrial-rich cells (MR cells) thought to be involved in proton (and bicarbonate) secretion containing significant H(+)-ATPase and Ca(2+)-ATPase and 2) the granular cells (G cells), postulated important in sodium reabsorption, having abundant Na(+)-K(+)-ATPase. That Na(+)-K(+)-ATPase activity was unchanged by either a calcium ionophore or a calcium channel blocker suggests that the decrease in SCC noted in the intact membrane is not directly mediated by changes in the sodium "pump." The decrease of H(+)-ATPase in MR cells, which resulted after the A-23187, suggests that it probably exerts a direct action on the proton pump, which decr...Continue Reading

Citations

Nov 13, 2001·American Journal of Physiology. Renal Physiology·H Y KwanX Yao

❮ Previous
Next ❯

Related Concepts

Related Feeds

ATP Synthases

ATP synthases are enzymes located in the inner mitochondrial membrane that catalyze the synthesis of ATP during cellular respiration. Discover the latest research on ATP synthases here.

Bladder Carcinoma In Situ

Bladder Carcinoma In Situ is a superficial bladder cancer that occurs on the surface layer of the bladder. Discover the latest research on this precancerous condition in this feed.