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Voltage-gated calcium channels in Pleurodeles oocytes: classification, modulation and functional roles
1Centre de Biologie Cellulaire, USTL 59655, Villeneuve d'Ascq, France. ouadid.halima@univ-lille1.fr
Zygote (Cambridge, England)
|July 4, 1998
Summary
Two calcium channel types in Pleurodeles oocytes, L-type and transient, show distinct seasonal expression. L-type calcium channels are crucial for oocyte maturation, with higher density during breeding seasons.
Area of Science:
- * Cellular and Molecular Biology
- * Reproductive Physiology
- * Ion Channel Physiology
Background:
- * Unfertilized Pleurodeles oocytes express two high voltage-activated calcium (Ca2+) channels: a slowly inactivating L-type Ca2+ channel and a transient Ca2+ channel.
- * L-type channels are dihydropyridine-sensitive, while transient channels are Ni2+-sensitive.
- * Protein kinases G and A differentially modulate L-type channel activity (facilitation and inhibition, respectively).
Purpose of the Study:
- * To investigate the functional expression and seasonal modulation of high voltage-activated Ca2+ channels in Pleurodeles oocytes.
- * To elucidate the role of L-type and transient Ca2+ channels in the regulation of oocyte maturation.
Main Methods:
- * Electrophysiological recordings to characterize high voltage-activated Ca2+ currents.
- * Pharmacological sensitivity testing using dihydropyridine and Ni2+.
- * Assessment of protein kinase effects (G and A) on channel activity.
- * Comparative analysis of channel expression during breeding and resting seasons.
Main Results:
- * Transient Ca2+ currents were exclusively observed during the resting season.
- * L-type Ca2+ currents were present during the breeding season (alone) and resting season (with transient currents).
- * Current density of L-type Ca2+ channels was significantly higher during the breeding season compared to the resting season.
Conclusions:
- * The expression and activity of L-type and transient Ca2+ channels in Pleurodeles oocytes are seasonally regulated.
- * The prominent presence and increased current density of L-type Ca2+ channels during the breeding season suggest a critical role in oocyte maturation regulation.