We have studied the changes in membrane potential induced by LH in cumulus and granulosa cells isolated from sheep antral follicles. The investigation was earned out by using a non-invasive technique based oil the use of a membrane potential sensitive probe, bis-oxonol. The membrane potential of mural granulosa cells was totally unaffected by LH, while that of cumulus or corona cells showed a marked depolarisation, starting 2-3 min after the addition of the hormone and plateauing after 5-10 min. None of the cells tested reacted to FSH. In the second part of the experiment the role of protein kinase A (PKA) and protein kinase C (PKC) in mediating the effect of LH was studied. The selective activation of PKA or PKC induced in cumulus-corona cells a rapid hyperpolarisation due re, increased Cl and K conductance respectively. By contrast, the simultaneous activation of the two kinases induced a rapid membrane depolarisation due to the progressive decrease in It conductance. The activation of each kinase or their combined stimulation did not induce any change ill the membrane potential of mural granulosa cells. These data demonstrated that LH has a depolarising effect regionally circumscribed to cumulus-corona cells and that this depolarisation depends on a reduction of K conductance caused by the activation of PKA and PKC.[...]
Activation of PKA and PKC mediates the depolarising effect of LH in ovine cumulus-corona cells
MATTIOLI, Mauro;BARBONI, Barbara;GIOIA, Luisa
1996-01-01
Abstract
We have studied the changes in membrane potential induced by LH in cumulus and granulosa cells isolated from sheep antral follicles. The investigation was earned out by using a non-invasive technique based oil the use of a membrane potential sensitive probe, bis-oxonol. The membrane potential of mural granulosa cells was totally unaffected by LH, while that of cumulus or corona cells showed a marked depolarisation, starting 2-3 min after the addition of the hormone and plateauing after 5-10 min. None of the cells tested reacted to FSH. In the second part of the experiment the role of protein kinase A (PKA) and protein kinase C (PKC) in mediating the effect of LH was studied. The selective activation of PKA or PKC induced in cumulus-corona cells a rapid hyperpolarisation due re, increased Cl and K conductance respectively. By contrast, the simultaneous activation of the two kinases induced a rapid membrane depolarisation due to the progressive decrease in It conductance. The activation of each kinase or their combined stimulation did not induce any change ill the membrane potential of mural granulosa cells. These data demonstrated that LH has a depolarising effect regionally circumscribed to cumulus-corona cells and that this depolarisation depends on a reduction of K conductance caused by the activation of PKA and PKC.[...]I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
