Low extracellular Ca 2+ activates a transient Cl − current in chicken ovarian granulosa cells
The effects of low Ca 2+ on ion currents in hen ovarian granulosa cells were examined. A fast activating and inactivating transient outward current (TOC) and a slowly activating outward current (SOC) could be observed. In the presence of normal Ca 2+ concentration (2.5 mM) and with a holding potenti...
Saved in:
Published in | American Journal of Physiology: Cell Physiology Vol. 279; no. 2; pp. C319 - C325 |
---|---|
Main Authors | , , |
Format | Journal Article |
Language | English |
Published |
01.08.2000
|
Online Access | Get full text |
Cover
Loading…
Summary: | The effects of low Ca
2+
on ion currents in hen ovarian granulosa cells were examined. A fast activating and inactivating transient outward current (TOC) and a slowly activating outward current (SOC) could be observed. In the presence of normal Ca
2+
concentration (2.5 mM) and with a holding potential of −80 mV, SOC was activated in all cells with command pulses more positive than −20 mV. In 2.5 mM Ca
2+
, TOC appeared in 10% of cells at the command pulse of +80 mV and in 60–85% of cells at +100 to +120 mV. In low-Ca
2+
solution and command potential of +80 mV (holding potential of −80 mV), the amplitude of TOC was enhanced in cells that expressed it in normal Ca
2+
, and TOC appeared in 43% of the cells that did not express it initially in normal Ca
2+
. At both normal and low Ca
2+
levels, TOC decreased as the holding potential became more positive. TOC was reduced in Cl
−
-deficient solution and in the presence of 5-nitro-2-(3-phenylpropylamino)benzoic acid, a Cl
−
channel blocker. These findings suggest that chicken granulosa cells express a Ca
2+
-inactivated TOC carried by Cl
−
. This current may serve as a signal for some of the reduced metabolic functions of granulosa cells associated with Ca
2+
deficiency. |
---|---|
ISSN: | 0363-6143 1522-1563 |
DOI: | 10.1152/ajpcell.2000.279.2.C319 |