Vasodilator responses to alpha-human-atrial natriuretic peptide in isolated omental and pulmonary arteries from rabbit and man.

In isolated vessels from the pulmonary and mesenteric/omental arterial circulations of rabbit and man, the effects of synthetic alpha-human atrial natriuretic peptide (alpha-hANP) were investigated. The vessels had an outer diameter of 0.6-1.2 mm and were contracted by noradrenaline (NA) and prostaglandin (PG) F2 alpha (mesenteric/omental arteries) or by 5-hydroxytryptamine (5-HT) and PGF2 alpha (pulmonary arteries). It was found that in rabbits, mesenteric vessels contracted by NA and PGF2 alpha were not significantly relaxed by alpha-hANP. Rabbit pulmonary vessels contracted by PGF2 alpha or 5-HT were concentration-dependently relaxed by alpha-hANP (maximum 70%). Human omental vessels contracted by NA and PGF2 alpha showed a moderate (30%) relaxation after addition of the peptide. Human pulmonary arteries contracted by 5-HT were relaxed by alpha-hANP almost to baseline, while PGF2 alpha-contracted vessels showed a maximum relaxation of 65%. It is concluded that alpha-hANP has a relatively selective effect on pulmonary arterial vessels from rabbit as well as man. The results suggest that the peptide may be involved in the regulation of pulmonary vascular tone.