Purinergic cation channels in neurons of rabbit vesical parasympathetic ganglia

Membrane current was recorded from neurons in rabbit vesical parasympathetic ganglia, utilizing single electrode voltage clamp techniques. ATP (0.1-1 mM) caused an inward current (IATP) associated with an increased 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 adenosine (0.1-2 mM) mimicked the actions of ATP. The IATP reversed its polarity at -12.1 +/- 1.4 mV. The amplitude of the IATP was depressed in low sodium solutions and in nominally calcium-free solutions but not in low chloride solutions. Suramin (10-100 microM) and reactive blue 2 (10-100 microM), P2-antagonists, reversibly depressed the IATP. In contrast, hexamethonium (100 microM) did not affect the IATP. These data suggest that ATP activates cation channels through P2X receptor subtypes in parasympathetic neurons.