Extracellular calcium protects against verapamil-induced metaphase-II arrest and initiation of apoptosis in aged rat eggs.
Non-specific L-type calcium channel blockers, such as verapamil (> or =50 microM), induce metaphase-II (M-II) arrest and apoptosis in aged rat eggs cultured in Ca(2+)-deficient medium. However, the effects of extracellular Ca(2+) on verapamil-induced M-II arrest and apoptosis have not yet been reported. We have demonstrated that postovulatory aging induced exit from M-II arrest by extruding a second polar body, a morphological sign of spontaneous egg activation (SEA). Verapamil inhibited SEA and induced egg apoptosis in a dose-dependent manner in Ca(2+)-deficient medium. The initiation of apoptotic features was observed at 50 microM of verapamil. Extracellular Ca(2+) (1.80 mM) reduced intracellular H2O2 level, bax protein expression, caspase-3 activity, DNA fragmentation and protected against 50 microM, but not higher concentrations of > or =100 microM in verapamil-induced egg apoptosis. These results suggest that extracellular Ca(2+) ions have a role during SEA and protect against verapamil induced apoptosis in aged rat eggs.
Chaube
S K
SK
Department of Zoology, Banaras Hindu University, Varanasi, Uttar Pradesh, India. shailchaubey@gmail.com
Tripathi
Anima
A
Khatun
Sabana
S
Mishra
S K
SK
Prasad
P V
PV
Shrivastav
T G
TG
D000818:Animals; D017209:Apoptosis; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D020746:Calcium Channels, L-Type / Q000378:metabolism; D053148:Caspase 3 / Q000378:metabolism; D016922:Cellular Senescence; D006861:Hydrogen Peroxide / Q000378:metabolism; D008677:Metaphase / Q000187:drug effects; D010063:Ovum / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D014700:Verapamil / Q000494:pharmacology*; D051028:bcl-2-Associated X Protein / Q000378:metabolism
D002121:Calcium Channel Blockers; D020746:Calcium Channels, L-Type; D051028:bcl-2-Associated X Protein; D006861:Hydrogen Peroxide; D014700:Verapamil; D053148:Caspase 3; D002118:Calcium