PURINERGIC CATION CHANNELS IN NEURONS OF RABBIT VESICAL PARASYMPATHETIC GANGLIA

Membrane current was recorded from neurons in rabbit vesical parasympa thetic ganglia, utilizing single electrode voltage clamp techniques. A TP (0.1-1 mM) caused an inward current (I-ATP) associated with an incr eased conductance at a holding potential of -50 mV. ADP (0.1-1 mM) and 5'-O-3-thiotriphosphate (0.1-0.6 mM) but not AMP (0.3-2 mM) and adeno sine (0.1-2 mM) mimicked the actions of ATP. The I-ATP reversed its po larity at -12.1 +/- 1.4 mV. The amplitude of the I-ATP was depressed i n low sodium solutions and in nominally calcium-free solutions but not in low chloride solutions. Suramin (10-100 mu M) and reactive blue 2 (10-100 mu M), P-2-antagonists, reversibly depressed the I-ATP. In con trast, hexamethonium (100 mu M) did not affect the I-ATP. These data s uggest that ATP activates cation channels through P-2X receptor subtyp es in rabbit parasympathetic neurons.