Expression of a rapidly inactivating Ca2+ channel in Pleurodeles oocytes during the resting season.
Two kinds of Ca2+ channel activities have been recorded in unfertilized Pleurodeles oocytes during the resting season: the previously described L-type and a transient one. The transient Ba current (I(Ba-t)) exhibited a voltage threshold of -36+/-7 mV, peaked at -18+/-8 mV and reversed around +50 mV. It showed a fast monoexponential decay with an inactivation time course of 31.4+/-1.7 ms at -20 mV. I(Ba-t) was insensitive to nifedipine and omega-conotoxin-GVIA but blocked by Ni2+ (50 microM). Moreover, Cd2+ also reduced I(Ba-t) but was less efficient than Ni2+. When using Ca2+ as the charge carrier, the amplitude and the decay of I(ca-t) were largely similar to those of I(Ba-t). These data demonstrated that the population of Ca2+ channels could be seasonally modulated in Pleurodeles oocytes.
Ouadid
H
H
Centre de Biologie Cellulaire, Laboratoire de Physiologie Cellulaire, SN3, USTL, Villeneuve d'Ascq, France. ouadid@pop.univ-lille1.fr
D000818:Animals; D001464:Barium / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism*; D005260:Female; D009532:Nickel / Q000494:pharmacology; D009543:Nifedipine / Q000494:pharmacology; D009865:Oocytes / Q000187:drug effects / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D010455:Peptides / Q000494:pharmacology; D010999:Pleurodeles; D012621:Seasons; D020866:omega-Conotoxin GVIA
D002121:Calcium Channel Blockers; D015220:Calcium Channels; D010455:Peptides; D001464:Barium; D009532:Nickel; D020866:omega-Conotoxin GVIA; D009543:Nifedipine; D002118:Calcium