[ATP-activated ion conductance in isolated smooth muscle cells of the urinary bladder of the guinea pig].

Smooth muscle cells of guinea pig urinary bladder were investigated by the intracellular perfusion and voltage clamp techniques. The application of ATP in concentration over 3.10(-8) mol/l elicited fast inward current. ADP, alpha, beta-methylene ATP and beta, gamma-methylene ATP had the similar effect. GTP, ITP, AMP and adenosine elicited no ionic current. AMP was a competitive blocker for receptors of ATP. No pharmacological distinctions were discovered between these receptors and ATP receptors of sensory neurons of the rat. ATP receptors had a fast desensitisation and extremely slow recovery of sensitivity to agonists. The rate of desensitisation decreased with the ATP concentration reduction.