L- and T-type voltage-gated Ca2+ channels in human granulosa cells: functional characterization and cholinergic regulation.
Using the whole-cell configuration of the patch-clamp technique, we have characterized two types of ionic currents through voltage-dependent Ca2+ channels in human granulosa cells. One is long-lasting, activates at approximately -20 mV, reaches the peak at approximately +20 mV, has an inactivation time constant of 132.5 +/- 5.6 msec at 20 mV, and is sensitive to dihydropyridines. The other is transient, activates at approximately -40 mV, peaks at approximately -10 mV, has an inactivation time constant of 38.8 +/- 1.8 msec at -10 mV, displays a voltage-dependent inactivation, and is sensitive to 100 microm Ni2+, but not to dihydropyridines. Biophysical and pharmacological properties of these currents indicate that they are gated through L- and T-type calcium channels, respectively. The cholinergic receptor agonist carbachol (50 microm) reduces the amplitude of the currents through both L-type (-34.7 +/- 6.4%; n = 10) and T-type (-52.6 +/- 7.4%; n = 8) channels, suggesting a possible role of these channels in the cholinergic regulation of human ovarian functions.
Platano
Daniela
D
Department of Human and General Physiology, University of Bologna, Via S. Donato 19/2, I-40127 Bologna, Italy.
Magli
M Cristina
MC
Ferraretti
Anna Pia
AP
Gianaroli
Luca
L
Aicardi
Giorgio
G
D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000502:physiology; D020746:Calcium Channels, L-Type / Q000187:drug effects / Q000502:physiology*; D020747:Calcium Channels, T-Type / Q000187:drug effects / Q000502:physiology*; D002217:Carbachol / Q000494:pharmacology*; D005260:Female; D006107:Granulosa Cells / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D008564:Membrane Potentials
D015220:Calcium Channels; D020746:Calcium Channels, L-Type; D020747:Calcium Channels, T-Type; D002217:Carbachol; D002118:Calcium