EFFECTS OF NATRIURETIC PEPTIDES AND ENDOTHELINS ON THE NERVE-EVOKED RELEASE OF ADENINE-NUCLEOTIDES AND NUCLEOSIDES IN GUINEA-PIG VAS-DEFERENS

Two members of the natriuretic peptide family (rANF(8-33) and pBNP(1-3 2)) and two members of the endothelin family (ET-1 and ET-2) have been studied for their effects on the neurogenically induced overflow of a denosine 5'-triphosphate (ATP), adenosine 5'-diphosphate (ADP), adenos ine 5'-monophosphate (AMP), and adenosine (ADO) from the isolated guin ea-pig vas deferens. rANF, pBNP, ET-1, and ET-2 each at 10 nM produced a significant increase in the evoked overflow of ATP, by 52, 85, 130, and 11.5%, respectively. None of the peptides altered the overflow of ADO. ET-1 and ET-2 each caused an increase in the overflow of ADP and AMP by an amount similar to their effects on ATP overflow, so that th e ratio ATP:ADP remained 1:1 throughout. Natriuretic peptides, however , affected the overflow of ADP and AMP to a lesser extent than ATP, re sulting in an ATP:ADP ratio of 2:1 after rANF and of 1.5:1 after pBNP. In addition, rANF or pBNP, but not ET-1 or ET-2, inhibited ecto-ATPas e activity, suggesting that this mechanism may contribute to the facil itatory effect of the natriuretic peptides on the nerve-evoked overflo w of ATP in this tissue.