title: Temperature dependence of gap junction properties in neonatal rat heart cells.
abstract: Cell pairs of neonatal rat hearts were used to study the influence of temperature on the electrical properties of gap junctions. A dual voltage-clamp method was adopted, which allowed the voltage gradient between the cells to be controlled and the intercellular current flow to be measured. Cell pairs with normal coupling revealed a positive correlation between the conductance of the junctional membranes, gj, and temperature. Cooling from 37 degrees C to 14 degrees C led to a steeper decrease in gj, cooling from 14 degrees C to -2 degrees C to a shallower decrease (37 degrees C: gj = 48.3 nS; 14 degrees C: gj = 21.4 nS; -2 degrees C: gj = 17.5 nS), corresponding to a temperature coefficient, Q10, of 1.43 and 1.14 respectively. The existence of two Q10 values implies that gj may be controlled by enzymatic reactions. When gj was low, i.e. below 5 nS (conditions: low temperature; treatment with 3 mM heptanol), it showed voltage-dependent gating. This property was not visible when gj was large, i.e. 20-70 nS (conditions: high temperature; normal saline), presumably because of series resistances (pipette resistance). Cell pairs with weak intrinsic coupling and normally coupled cell pairs treated with 3 mM heptanol revealed a positive correlation between the conductance of single gap-junction channels, gamma j, and temperature (37 degrees C: 75.6 pS; -2 degrees C: 19.6 pS), corresponding to a Q10 of 1.41.
authors.affiliation: Department of Physiology, Bern, Switzerland.
authors.forename: F F
authors.initials: FF
authors.lastname: Bukauskas
authors.forename: R
authors.initials: R
authors.lastname: Weingart
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002462:Cell Membrane / Q000502:physiology; D004553:Electric Conductivity; D004594:Electrophysiology; D007365:Intercellular Junctions / Q000502:physiology*; D007473:Ion Channels / Q000502:physiology; D009206:Myocardium / Q000648:ultrastructure*; D051381:Rats; D017208:Rats, Wistar; D013696:Temperature
chemical_list: D007473:Ion Channels