Voltage sensitivity of gap junction currents in rat osteoblast-like cells.
The dependence of macroscopic gap junctional conductance (g(j)) upon transjunctional voltage (Vj) was examined in 39 paired osteoblast-like (OB) cells from primary cultures using the double whole cell patch clamp technique. OB cells were derived from calvarial explants of new-born rats. Instantaneous current-voltage (Ij-Vj) relationships of OB cell pairs (n = 6) were linear in the entire voltage range (-150 < Vj < 150 mV) examined. The steady-state Ij-Vj relationship was non-linear for V > or = +/-60 mV. The curve for the normalised steady-state junctional conductance-voltage relationship (Gss/G0-Vj) was bell-shaped, and was fitted with a two-state Boltzmann equation with a minimum conductance (Gmin) of 0.2-0.3, and a half deactivation voltage (Vo) of +/-83 mV. In two recordings unitary gap junction channel activity was observable. The linear I-V relationships revealed a single channel conductance of approximately 100 pS. Application of parathyroid hormone (10(-8) M) had no effect on the voltage dependence nor the magnitude of macroscopic currents (n = 7).
Schirrmacher
K
K
Institut für Physiologie, Universität-GH Essen, Germany. karin.schirrmacher@uni-essen.de
Ramanan
S V
SV
Cronin
K
K
Peterson
E
E
Brink
P R
PR
D000200:Action Potentials; D000818:Animals; D000831:Animals, Newborn; D017629:Gap Junctions / Q000737:chemistry / Q000378:metabolism*; D010006:Osteoblasts / Q000378:metabolism*; D010281:Parathyroid Hormone / Q000378:metabolism; D018408:Patch-Clamp Techniques; D051381:Rats
D010281:Parathyroid Hormone