Effect of Intracellular Dialysis of ATP on the Hyperpolarization-Activated Cation Current in Rat Dorsal Root Ganglion Neurons

You Komagiri, Naoki Kitamura
2003 Journal of Neurophysiology  
Komagiri, You and Naoki Kitamura. Effect of intracellular dialysis of ATP on the hyperpolarization-activated cation current in rat dorsal root ganglion neurons. . The mechanism of the effect of intracellular ATP on the hyperpolarization-activated non-selective cation current (I h ) in rat dorsal root ganglion neurons was investigated using a whole cell voltage-clamp technique. Under voltage-clamp conditions, I h was activated by hyperpolarizing pulses raised to a voltage of between -70 and -130
more » ... mV. The activation curve of I h in rat dorsal root ganglion (DRG) neurons shifted by about 15 mV in the positive direction with an intracellular solution containing 1 mM cAMP. When ATP (2 mM) was applied intracellularly, the half-maximal activation voltage (V half ) of I h shifted from -97.4 Ϯ 1.9 to -86.8 Ϯ 1.6 mV, resulting in an increase in the current amplitude of I h by the pulse to between -80 and -90 mV. In the presence of an adenylate cyclase inhibitor, SQ-22536 (100 M), the intracellular dialysis of ATP also produced a shift in the voltage-dependence of I h in rat DRG neurons, indicating that the effect of ATP was not caused by cAMP converted by adenylate cyclase. Intracellular dialysis of a nonhydrolysable ATP analog, AMP-PNP or ATP-␥-S, also produced a positive shift in the voltage-dependence of I h activation, suggesting that the effect of ATP results from its direct action on the channel protein. These results indicate that cytosolic ATP directly regulates the voltage dependence of I h activation as an intracellular modulating factor. M E T H O D S Cell culture Rat DRG neurons were isolated from adult male Sprague-Dawley rats (7-12 wk old), using procedures that have been reported previously (Kim et al. 1980; Yong et al. 1988 ).
doi:10.1152/jn.00442.2003 pmid:12853439 fatcat:67rtguljzfaufgwmod7e7xvy2i