Seasonal influences on the functional expression of the endogenous L-type Ca2+ channels in Pleurodeles oocytes: role of cAMP?
We have investigated the seasonal regulation of the Ba current (IBa) through the L-type Ca2+ channels in Pleurodeles oocytes and its relation with the intracellular cAMP level. IBa-density remained relatively constant from January to February, increased from March to April (with a maximum increase in March) and decreased from May to July. While the permeable cAMP analogue 8Br-cAMP reduced IBa during the breeding season, it was without effect during the resting season. However, IBa recorded during the two seasons was increased by a dihydropyridine agonist Bay K 8644 and blocked by cadmium. The main conclusion is that the seasonal reduction in the L-type Ca2+ current amplitude may be correlated with a high intracellular cAMP level and may account for the inability of oocytes to mature during the resting season.
Ouadid-Ahidouch
H
H
Centre de Biologie Cellulaire, Laboratoire de Physiologie Cellulaire, SN3, USTL, Villeneuve d'Ascq, France. ouadid@pop.univ-lille1.fr
Van Coppenolle
F
F
D000818:Animals; D015220:Calcium Channels / Q000187:drug effects*; D020746:Calcium Channels, L-Type; D000242:Cyclic AMP / Q000494:pharmacology*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D005260:Female; D009865:Oocytes / Q000502:physiology*; D018408:Patch-Clamp Techniques; D010999:Pleurodeles / Q000502:physiology*; D012621:Seasons
D015220:Calcium Channels; D020746:Calcium Channels, L-Type; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases