Effect of calmodulin antagonists on calcium pump of ram spermatozoa plasma membrane.
Plasma membranes isolated from ram spermatozoa contain calmodulin, which represents approximately 0.03% of the total sperm calmodulin and 0.025% of the membrane protein. When membranes were isolated in the presence of ethylene glycol (beta-aminoethyl ether) N,N,N',N'-tetraacetic acid (EGTA), the amount of calmodulin associated with the plasma membranes was reduced by only 20%. The ATP-dependent calcium transport activity of the isolated plasma membranes is not enhanced by adding calmodulin and not inhibited by the calmodulin antagonists trifluoperazinc (TFP), compound 48/80, or calmidazolium. In fact, there is an enhancement of calcium uptake by the calmodulin antagonists and this enhancement can be blocked by the Ca2+-channel blocker D-600. It is suggested that the ATP-dependent calcium transport activity in the plasma membrane of ram spermatozoa is not regulated by calmodulin.
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002147:Calmodulin / Q000037:antagonists & inhibitors*; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D004533:Egtazic Acid / Q000494:pharmacology; D005711:Gallopamil / Q000494:pharmacology; D007093:Imidazoles / Q000494:pharmacology; D008297:Male; D012756:Sheep; D013094:Spermatozoa / Q000166:cytology* / Q000378:metabolism; D014268:Trifluoperazine / Q000494:pharmacology; D003189:p-Methoxy-N-methylphenethylamine / Q000494:pharmacology
D002147:Calmodulin; D007093:Imidazoles; D014268:Trifluoperazine; D005711:Gallopamil; D003189:p-Methoxy-N-methylphenethylamine; C031938:calmidazolium; D004533:Egtazic Acid; D002118:Calcium