The temperature dependence of the adrenergic Na+/H+ exchanger of trout erythrocytes.
The effects of temperature upon the adrenergic Na+/H+ exchange of rainbow trout erythrocytes have been studied in vitro. The initial rates of H+ ejection and of increase of intracellular Na+ [( Na+]i) in adrenergically stimulated cells were highly temperature-dependent, with apparent Arrhenius activation energies of 112.8 +/- 10.0 (mean +/- S.D., N = 4) and 84.1 +/- 3.0 kJ mol-1 (N = 3), respectively. The steady-state [Na+]i following stimulation decreased progressively with cooling, whilst the time required for [Na+]i to return to control values after removal of agonist was greatly increased. The change in intracellular pH resulting from adrenergic stimulation was reduced by cooling, such that at 4 degrees C adrenergic responses were barely measurable. The effect of temperature upon the steady-state [Na+]i and pHi was probably caused by a disparity in the temperature dependence of the transport mechanisms that contribute to the respective steady states.
Cossins
A R
AR
Department of Environmental and Evolutionary Biology, University of Liverpool.
Kilbey
R V
RV
D000818:Animals; D001692:Biological Transport / Q000502:physiology; D002352:Carrier Proteins / Q000502:physiology*; D004912:Erythrocytes / Q000502:physiology*; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology; D017923:Sodium-Hydrogen Exchangers; D013696:Temperature; D014337:Trout
D002352:Carrier Proteins; D017923:Sodium-Hydrogen Exchangers; D007545:Isoproterenol