Human, pig and guinea-pig bladder smooth muscle cells generate similar inward currents in response to purinoceptor activation.

The contribution of purinergic neurotransmission to bladder excitation in pigs and man is small. Exogenously-applied adenosine-trisphosphate (ATP) however, elicits large inward currents in dispersed bladder smooth muscle cells in both species. The essential properties of the ATP-induced current in human and pig detrusor are similar and the current intensity is comparable to those in the guinea-pig, which has a powerful purinergic excitatory innervation. This suggests that other features of the tissue such as the closeness of the innervation and the degree of cell-to-cell coupling may be important in determining the effectiveness of purinergic transmission.