Effects of dipyridamole on neurogenic and non-neurogenic dilator responses of arterial smooth muscle.

1 In the isolated, perfused parametrial artery of the guinea-pig dipyridamole (10-100 ng/ml) potentiated dilator responses to adenosine 5'-triphosphate (ATP), glyceryl trinitrate and non-cholinergic, non-adrenergic inhibitory nerve stimulation to similar extents. In contrast dilator responses to acetylcholine were generally unaffected or reduced.2 These results support previous electro-physiological evidence that in this preparation cholinergic vasodilatation is mediated by a cellular mechanism different from that involved in the response to non-cholinergic dilator nervous activation.3 The results also suggest that potentiation of a neurally-mediated inhibitory response of smooth muscle by dipyridamole does not necessarily implicate ATP as the transmitter involved in this response.