Impact of Ca2+ flux inhibitors on acrosome reaction of hamster spermatozoa.
Ca(2+) plays a prominent role in the regulation of critical functions of spermatozoa, such as capacitation, acrosome reaction (AR), and fertilization. While there is consensus that Ca(2+) is essential, researchers have reported conflicting results as to what happens to Ca(2+) flux across the sperm membrane during capacitation and AR. The purpose of the present study was to further delineate the function of Ca(2+) channels and their role in sperm capacitation and AR. Epididymides were obtained from healthy adult male hamsters. Spermatozoa were washed with modified Tyrode medium supplemented with 0.3% bovine serum albumin, adjusted to 4.5 x 10(7) motile sperm/mL and incubated in 200-microL droplets for 4 hours at 37 degrees C in the presence of trifluoperazine (TFP), a calmodulin inhibitor, at 25, 50, 100, or 150 nM; verapamil (VP), a Ca(2+) channel inhibitor, at 25, 50, 100, or 150 nM; or nifedipine (NF), a voltage-dependent Ca(2+) channel inhibitor, at 50, 100, 200, or 400 nM. Spermatozoa were assessed for AR by using Coomassie brilliant blue staining techniques. Results indicated that incubation of sperm with Ca(2+) channel inhibitors for 4 hours significantly reduced AR in the study groups (TFP: 88% +/- 2.3%, 65% +/- 2.0%, 60% +/- 2.2%, 54 % +/- 2.2%, respectively; VP: 45% +/- 1.3%, 23 % +/- 1.2%, 12% +/- 1.0%, 8% +/- 0.6%, respectively; and NF: 11% +/- 0.8%, 9% +/- 0.3%, 7.0% +/- 0.1%, 6.0% +/- 0.1%, respectively) compared with control group (95% +/- 3.0%, P < .05). However, increasing the concentrations of TFP and NF did not result in further suppression of AR. In summary, the antagonists of calmodulin and Ca(2+) channel inhibitors suppress sperm AR.
Feng
Huai L
HL
The Center for Human Reproduction, Department of Obstetrics and Gynecology, North Shore University Hospital, 300 Community Drive, Manhasset, NY 11030, USA. hfeng@nshs.edu
Han
Yi B
YB
Hershlag
Avner
A
Zheng
Lei J
LJ
D020101:Acrosome Reaction / Q000502:physiology*; D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D002147:Calmodulin / Q000037:antagonists & inhibitors; D006224:Cricetinae; D003412:Cricetulus; D008297:Male; D009543:Nifedipine / Q000494:pharmacology; D013094:Spermatozoa / Q000187:drug effects / Q000502:physiology*; D014268:Trifluoperazine / Q000494:pharmacology*; D014700:Verapamil / Q000494:pharmacology*
D002121:Calcium Channel Blockers; D002147:Calmodulin; D014268:Trifluoperazine; D014700:Verapamil; D009543:Nifedipine