EVOKED NORADRENALINE RELEASE IN THE RABBIT EAR ARTERY - ENHANCEMENT BY PURINES, ATTENUATION BY NEUROPEPTIDE-Y AND LACK OF EFFECT OF CALCITONIN-GENE-RELATED PEPTIDE

1 Adenosine (30 mu M) and its analogues 5'-N-ethylcarboxaminoadenosine (5 and 30 mu M)and L-phenylisopropyladenosine (5 and 30 mu M), potentiated the evoked but not spontaneous release of tritiated noradrenaline in the rabbit central ear artery. 2 Prejunctional inhibition of the evoked but not spontaneous release of tritiated noradrenaline by 100 nM neuropeptide Y is greater at 2 min than at 10 min after superfusion of the peptide. 3 Calcitonin gene-related peptide (2.63 to 263 nM) did not affect the evoked or spontaneous release of tritiated noradrenaline in this preparation. 4 These results are discussed in terms of prejunctional modulation of sympathetic transmission in the rabbit central ear artery.