INTRACELLULAR ATP CHANGES THE VOLTAGE-DEPENDENCE OF DELAYED RECTIFIERPOTASSIUM CURRENT IN BULLFROG PRIMARY AFFERENT NEURONS

Dissociated bullfrog dorsal root ganglion cells were voltage-clamped i n the whole-cell configuration to study the steady-state activation an d inactivation curves for a delayed rectifier potassium current. The 5 0%-activation of the current occurred at +15mV when measured with ATP (5mM) in the pipette solution as opposed to -11 mV with 5'-adenylylimi dodiphosphate (AMP-PNP, 5mM) and -15 mV with adenosine 5'-O-(3-thiotri phosphate) (5 mM). The 50%-inactivation of the current occured at -6 m V with ATP but at -31 mM with AMP-PNP. The results suggest that intrac ellular ATP modulates voltage-dependence of the delayed rectifier in a mphibian afferent neurons.