Details
| Original language | English |
|---|---|
| Pages (from-to) | 165-76 |
| Number of pages | 12 |
| Journal | The journal of membrane biology |
| Volume | 194 |
| Issue number | 3 |
| Publication status | Published - 1 Aug 2003 |
Abstract
Gap junctional communication between granulosa cells seems to play a crucial role for follicular growth and atresia. Application of the double whole-cell patch-clamp- and ratiometric fura-2-techniques allowed a simultaneous measurement of gap junctional conductance ( G(j)) and cytoplasmic concentration of free Ca(2+) ([Ca(2+)](i)) in a rat granulosa cell line GFSHR-17. The voltage-dependent gating of G(j) varied for different cell pairs. One population exhibited a bell-shape dependence of G(j) on transjunctional voltage, which was strikingly similar to that of Cx43/Cx43 homotypic gap junction channels expressed in pairs of oocytes of Xenopus laevis. Within 15-20 min, gap junctional uncoupling occurred spontaneously, which was preceded by a sustained increase of [Ca(2+)](i) and accompanied by shrinkage of cellular volume. These responses to the whole-cell configuration were avoided by absence of extracellular Ca(2+), blockage of K(+) efflux, or addition of 8-bromoguanosine 3',5'-cyclic monophosphate (8-Br-cGMP) to the pipette solution. Even in the absence of extracellular Ca(2+) or blockage of K(+) efflux, formation of whole-cell configuration generated a Ca(2+) spike that could be suppressed by the presence of 8-Br-cGMP. We propose that intracellular cGMP regulates Ca(2+) release from intracellular Ca(2+) stores, which activates sustained Ca(2+) influx, K(+) efflux and cellular shrinkage. We discuss whether gap junctional conductance is directly affected by cGMP or by cellular shrinkage and whether gap junctional coupling and/or cell shrinkage is involved in the regulation of apoptotic/necrotic processes in granulosa cells.
Keywords
- Animals, Calcium/metabolism, Calcium Signaling/drug effects, Cell Communication/drug effects, Cell Size/drug effects, Chelating Agents/pharmacology, Connexins/metabolism, Cyclic GMP/analogs & derivatives, Cytoskeleton/drug effects, Egtazic Acid/pharmacology, Female, Fura-2/metabolism, Gap Junctions/drug effects, Granulosa Cells/drug effects, Ion Channel Gating, Ion Transport/drug effects, Patch-Clamp Techniques, Potassium/metabolism, Rats
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In: The journal of membrane biology, Vol. 194, No. 3, 01.08.2003, p. 165-76.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Regulation of ion fluxes, cell volume and gap junctional coupling by cGMP in GFSHR-17 granulosa cells
AU - Ngezahayo, A
AU - Altmann, B
AU - Kolb, H-A
PY - 2003/8/1
Y1 - 2003/8/1
N2 - Gap junctional communication between granulosa cells seems to play a crucial role for follicular growth and atresia. Application of the double whole-cell patch-clamp- and ratiometric fura-2-techniques allowed a simultaneous measurement of gap junctional conductance ( G(j)) and cytoplasmic concentration of free Ca(2+) ([Ca(2+)](i)) in a rat granulosa cell line GFSHR-17. The voltage-dependent gating of G(j) varied for different cell pairs. One population exhibited a bell-shape dependence of G(j) on transjunctional voltage, which was strikingly similar to that of Cx43/Cx43 homotypic gap junction channels expressed in pairs of oocytes of Xenopus laevis. Within 15-20 min, gap junctional uncoupling occurred spontaneously, which was preceded by a sustained increase of [Ca(2+)](i) and accompanied by shrinkage of cellular volume. These responses to the whole-cell configuration were avoided by absence of extracellular Ca(2+), blockage of K(+) efflux, or addition of 8-bromoguanosine 3',5'-cyclic monophosphate (8-Br-cGMP) to the pipette solution. Even in the absence of extracellular Ca(2+) or blockage of K(+) efflux, formation of whole-cell configuration generated a Ca(2+) spike that could be suppressed by the presence of 8-Br-cGMP. We propose that intracellular cGMP regulates Ca(2+) release from intracellular Ca(2+) stores, which activates sustained Ca(2+) influx, K(+) efflux and cellular shrinkage. We discuss whether gap junctional conductance is directly affected by cGMP or by cellular shrinkage and whether gap junctional coupling and/or cell shrinkage is involved in the regulation of apoptotic/necrotic processes in granulosa cells.
AB - Gap junctional communication between granulosa cells seems to play a crucial role for follicular growth and atresia. Application of the double whole-cell patch-clamp- and ratiometric fura-2-techniques allowed a simultaneous measurement of gap junctional conductance ( G(j)) and cytoplasmic concentration of free Ca(2+) ([Ca(2+)](i)) in a rat granulosa cell line GFSHR-17. The voltage-dependent gating of G(j) varied for different cell pairs. One population exhibited a bell-shape dependence of G(j) on transjunctional voltage, which was strikingly similar to that of Cx43/Cx43 homotypic gap junction channels expressed in pairs of oocytes of Xenopus laevis. Within 15-20 min, gap junctional uncoupling occurred spontaneously, which was preceded by a sustained increase of [Ca(2+)](i) and accompanied by shrinkage of cellular volume. These responses to the whole-cell configuration were avoided by absence of extracellular Ca(2+), blockage of K(+) efflux, or addition of 8-bromoguanosine 3',5'-cyclic monophosphate (8-Br-cGMP) to the pipette solution. Even in the absence of extracellular Ca(2+) or blockage of K(+) efflux, formation of whole-cell configuration generated a Ca(2+) spike that could be suppressed by the presence of 8-Br-cGMP. We propose that intracellular cGMP regulates Ca(2+) release from intracellular Ca(2+) stores, which activates sustained Ca(2+) influx, K(+) efflux and cellular shrinkage. We discuss whether gap junctional conductance is directly affected by cGMP or by cellular shrinkage and whether gap junctional coupling and/or cell shrinkage is involved in the regulation of apoptotic/necrotic processes in granulosa cells.
KW - Animals
KW - Calcium/metabolism
KW - Calcium Signaling/drug effects
KW - Cell Communication/drug effects
KW - Cell Size/drug effects
KW - Chelating Agents/pharmacology
KW - Connexins/metabolism
KW - Cyclic GMP/analogs & derivatives
KW - Cytoskeleton/drug effects
KW - Egtazic Acid/pharmacology
KW - Female
KW - Fura-2/metabolism
KW - Gap Junctions/drug effects
KW - Granulosa Cells/drug effects
KW - Ion Channel Gating
KW - Ion Transport/drug effects
KW - Patch-Clamp Techniques
KW - Potassium/metabolism
KW - Rats
U2 - 10.1007/s00232-003-2033-9
DO - 10.1007/s00232-003-2033-9
M3 - Article
C2 - 14502429
VL - 194
SP - 165
EP - 176
JO - The journal of membrane biology
JF - The journal of membrane biology
SN - 0022-2631
IS - 3
ER -