Abstract
Prolonged contact of the rat superior cervical ganglia (SCG) with the purine α,β-methylene-ATP (α,β-Me-ATP) selectively depressed responses to ATP and α,β-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 α,β-Me-ATP, potassium or adenosine. These results are consistent with the presence of P2-purinoceptors and pyrimidinoceptors on the rat SCG and the hypothesis that pyrimidinoceptors exist within the nervous system.