Related Experiment Videos
Action of palytoxin on apical H+/K+-ATPase in rat colon
Georgios Scheiner-Bobis1, Thomas Hübschle, Martin Diener
1Institute for Biochemistry and Endocrinology, Institute for Veterinary Physiology, Justus-Liebig-University Giessen, Germany. Georgios.Scheiner-Bobis@vetmed.uni-giessen.de
Abstract:
Palytoxin stimulated a cation-dependent short-circuit current (Isc) in rat distal and proximal colon in a concentration-dependent fashion when applied to the mucosal surface of the tissue. The distal colon exhibited a higher sensitivity to the toxin. The palytoxin-induced Isc was blocked by vanadate but was resistant to ouabain or scilliroside, suggesting the conversion of a vanadate-sensitive H+/K+-ATPase into an electrogenic cation transporter. Cation substitution experiments with basolaterally depolarized tissues suggested an apparent permeability of the palytoxin-induced conductance of Na+>K+>Li+. Immunohistochemical control experiments confirmed the absence of the Na+/K+-ATPase in the apical membrane. Consequently, the pore-forming action of palytoxin is not restricted to Na+/K+-ATPase but is also observed with the colonic H+/K+-ATPase.