Abstract
Summary In the isolated urinary bladder of the toad, 10−5–10−4M 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.