EVIDENCE FROM DESENSITIZATION STUDIES FOR DISTINCT RECEPTORS FOR ATP AND UTP ON THE RAT SUPERIOR CERVICAL-GANGLION

Prolonged contact of the rat superior cervical ganglia (SCG) with the purine alpha,beta-methylene-ATP (alpha,beta-Me-ATP) selectively depressed responses to ATP and alpha,beta-Me-ATP but not responses to uridine 5'-triphosphate (UTP), potassium or adenosine. Prolonged contact with the pyrimidine UTP selectively depressed responses to UTP but not responses evoked by alpha,beta-Me-ATP, potassium or adenosine. These results are consistent with the presence of P-2-purinoceptors and pyrimidinoceptors on the rat SCG and the hypothesis that pyrimidinoceptors exist within the nervous system.