Vanadate: non-selective inhibition of transepithelial transport of Na+, H+ and water.

In the isolated urinary bladder of the toad, 10(-5)-10(-4)M orthovanadate produces inhibition of the active transport of Na+ and H+ ions as well as of antidiuretic hormone-mediated osmotic flow of water. Since transport of H+ ions and osmotic water flow are not inhibited when (Na+ + K+)-ATPase is inhibited by ouabain, biological actions of vanadate are not necessarily related to inhibition of (Na+ + K+)-ATPase.