Studies on relationship between Na,K-ATPase activity and sperm capacitation in guinea pig.
In order to elucidate the biochemical mechanism of sperm capacitation, the relationship between plasmalemma Na,K-ATPase, capacitation and acrosome reaction was investigated. Plasmalemma of guinea pig spermatozoa was isolated by sucrose gradient centrifugation for the determination of Na,K-ATPase activity. As far as the authors are aware, the Na,K-ATPase activity in plasmalemma of the guinea pig has never been detected. By treating sperm plasmalemma with 0.05% DOC (deoxycholate), enzyme activity could be quantitatively measured. After spermatozoa were incubated in capacitation medium for 8 h, Na,K-ATPase activity was found to be decreased to 35.6% as compared with that before incubation. The spermatozoa incubated for 10.5 h in capacitation medium containing 1 and 5 mumol/L ouabain showed 46.5% and 64.4% acrosome reactions respectively, while the acrosome reaction of the control group was only 27.4%. The above results suggest that the decrease in the Na,K-ATPase activity of guinea pig spermatozoa may be a prerequisite for capacitation. Experimental results demonstrated for the first time that Na,K-ATPase activity exists in the sperm plasmalemma of the guinea pig. It was further found that the decrease of Na,K-ATPase activity of plasmalemma enhances sperm capacitation. It is suggested that sperm capacitation in the guinea pig is possibly induced by the decrease in plasmalemma Na,K-ATPase and, as a consequence, the intracellular Na+ is increased, which would benefit the exchange of Na+out/Ca++in and the onset of acrosome reaction.
Hang
H Y
HY
Department of Endocrinology and Laboratory of Reproductive Biology, Institute of Zoology, Beijing, PRC.
Feng
B Y
BY
Zhang
Z Y
ZY
D000818:Animals; D002462:Cell Membrane / Q000201:enzymology; D003840:Deoxycholic Acid / Q000494:pharmacology; D006168:Guinea Pigs; D008297:Male; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D013075:Sperm Capacitation / Q000187:drug effects; D013094:Spermatozoa / Q000201:enzymology / Q000648:ultrastructure*
D003840:Deoxycholic Acid; D000254:Sodium-Potassium-Exchanging ATPase