TONE-DEPENDENT VASODILATOR RESPONSES TO PROADRENOMEDULLIN NH2-TERMINAL-20 PEPTIDE IN THE HINDQUARTERS VASCULAR BED OF THE RAT

Responses to proadrenomedullin NH2-terminal 20 peptide (PAMP) were inv estigated in the systemic and hindquarters vascular bed of the rat. In travenous injections of PAMP and adrenomedullin (ADM) produced dose-re lated decreases in systemic arterial and hindquarters perfusion pressu re, which were not altered by alpha-receptor or adrenergic nerve termi nal blocking agents. PAMP was 100-fold less potent than ADM, and hindq uarters vasodilator responses to both peptides were similar in innerva ted and denervated preparations. When baseline tone was increased with phenylephrine and U46619 or decreased with sodium nitroprusside, vaso dilator responses to PAMP and ADM were correlated with the basal level of tone, suggesting that responses to both peptides are dependent on the baseline level of vasoconstrictor tone in the hindquarter vascular bed of the rat. (C) 1997 Elsevier Science Inc.