Endothelium removal does not affect potentiation by neuropeptide Y in rabbit ear artery

Influence of endothelial cells on the effect of neuropeptide Y (NPY) was investigated. NPY (30 nM) doubled the vasoconstriction elicited by transmural nerve stimulation (8 pulses at 8 Hz) in the perfused rabbit ear artery with or without endothelium. Conditions that increase the biophase concentration of norepinephrine, longer stimulation trains or application of yohimbine, decreased the potentiation by NPY, although in the presence of cocaine potentiation by NPY was unchanged. However, no significant differences between control and endothelium-removed arteries were revealed. Thus modulation of adrenergic neurotransmission by NPY does not depend on endothelium-derived vasoactive substances.