L-type calcium channels are preferentially coupled to endocytosis in bovine chromaffin cells.
Exocytosis and endocytosis are Ca(2+)-dependent processes. The contribution of high-voltage activated Ca(2+) channels subtypes to exocytosis has been thoroughly studied in chromaffin cells. However, similar reports concerning endocytosis are unavailable. Thus, we studied here the effects of blockers of L (nifedipine), N (omega-conotoxin GVIA) and P/Q (omega-agatoxin IVA) Ca(2+) channel on Ca(2+) currents (I(Ca)), Ca(2+) entry (Q(Ca)), as well as on the changes in membrane capacitance (C(m)) in perforated-patch voltage-clamped bovine adrenal chromaffin cells. Using 500-ms pulses to 0 or +10 mV, given from a holding potential of -80 mV and 2 mM Ca(2+) we found that omega-conotoxin GVIA affected little the exo-endocytotic responses while omega-agatoxin IVA markedly blocked those responses. However, nifedipine blocked little exocytosis but almost completely inhibited endocytosis. We conclude that L-type Ca(2+) channels seem to be selectively coupled to endocytosis.
Rosa
Juliana Martins
JM
Instituto Teófilo Hernando, Departamento de Farmacología y Terapéutica, Facultad de Medicina, Universidad Autónoma de Madrid, C/ Arzobispo Morcillo 4, 28029 Madrid, Spain.
de Diego
Antonio M G
AM
Gandía
Luis
L
García
Antonio G
AG
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020746:Calcium Channels, L-Type / Q000502:physiology*; D020013:Calcium Signaling / Q000502:physiology*; D002417:Cattle; D002478:Cells, Cultured; D019439:Chromaffin Cells / Q000502:physiology*; D004705:Endocytosis / Q000502:physiology*
D020746:Calcium Channels, L-Type; D002118:Calcium