title: Free calcium in full grown Xenopus laevis oocyte following treatment with ionophore A 23187 or progesterone.
abstract: Free intracellular Ca2+ was monitored in isolated Xenopus laevis oocyte during induced maturation using the Ca2+ -sensitive luminescent protein, aequorin. Internal free Ca2+ was not precisely measured but data suggest it was quite low (in the micromolar range). No change in internal free Ca2+ was detected during maturation induced either by progesterone or by p-chloromercuribenzoate. By contrast, the ionophore A 23187 gave an increase in the free Ca2+ level when there was a raised external Ca2+ (10 mM), conditions which also induce oocyte maturation. About 3 h after progesterone or p-chloromercuribenzoate stimulation, the oocyte membrane potential decreased by about 50 mV while the membrane resistance increased transitorily.
mesh_terms: D000331:Aequorin; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D000001:Calcimycin / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D002729:Chloromercuribenzoates / Q000494:pharmacology; D005260:Female; D008564:Membrane Potentials / Q000187:drug effects; D009865:Oocytes / Q000187:drug effects* / Q000502:physiology; D009866:Oogenesis / Q000187:drug effects; D010063:Ovum / Q000187:drug effects*; D011374:Progesterone / Q000494:pharmacology*; D014981:Xenopus
chemical_list: D000900:Anti-Bacterial Agents; D002729:Chloromercuribenzoates; D000001:Calcimycin; D011374:Progesterone; D000331:Aequorin; D002118:Calcium