title: Inhibitory effect of calmodulin inhibitors on palytoxin-induced K+ release from rabbit erythrocytes.
abstract: Palytoxin (PTX) caused K+ release from rabbit erythrocytes at a concentration as low as 10(-11) M. The K+ release due to PTX at a concentration below 10(-9) M was dependent on Ca2+ in medium. The effect of Ca2+ was substituted fully by Sr2+ and partially by Ba2+. W-7 (2 X 10(-4) M), a known inhibitor of calmodulin, markedly inhibited the rate of K+ release due to PTX. W-5 (2 X 10(-4) M), an analog of W-7 with lower affinity to calmodulin than W-7, showed weaker inhibition. Other calmodulin antagonists, such as prenylamine, chlorpromazine and compound 48/80, also inhibited the PTX-induced K+ release. These results suggest that the K+ release induced by PTX involves the process(es) mediated by intracellular Ca2+ and calmodulin.
mesh_terms: D000178:Acrylamides; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002147:Calmodulin / Q000037:antagonists & inhibitors*; D003064:Cnidarian Venoms / Q000494:pharmacology*; D004912:Erythrocytes / Q000187:drug effects / Q000378:metabolism*; D011188:Potassium / Q000097:blood*; D011817:Rabbits; D013324:Strontium / Q000494:pharmacology; D013449:Sulfonamides / Q000494:pharmacology; D013997:Time Factors; D000095702:Polyether Toxins
chemical_list: D000178:Acrylamides; D002118:Calcium; D002147:Calmodulin; D003064:Cnidarian Venoms; D011188:Potassium; D013324:Strontium; D013449:Sulfonamides; C017967:W 7; C034700:N-(6-aminohexyl)-1-naphthalenesulfonamide; C010272:palytoxin; D000095702:Polyether Toxins