EFFECTS OF INTRADERMAL INJECTION OF ATRIAL-NATRIURETIC-PEPTIDE

Atrial natriuretic peptide (ANP) causes mast cell degranulation in rat s in vivo and in vitro but is bronchodilator in humans. The aim of thi s study was to investigate the wheal and flare dose-response to intrad ermal injection of alpha-human ANP in normal humans. Eight normal subj ects received five 30 mu l injections containing 1, 10, 39, 78, 117 pm ol ANP and one each of normal saline, histamine 675 pmol and substance P 30 pmol. Maximum ANP flare response was greater but not significant ly than that to saline at 1.55 +/- 0.6 (mean +/- s.e. mean) compared w ith 0.42 +/- 0.17 cm(2), but much less than to histamine 9.86 +/- 0.97 or to substance P 12.5 +/- 1.2. Maximum ANP wheal response was signif icantly greater than that to saline at 0.38 +/- 0.08 compared with 0.1 8 +/- 0.05 cm(2) (difference between means 0.20, 95% CI 0.05, 0.35), b ut much less than to histamine 0.75 +/- 0.06 or to substance P 1.05 +/ - 0.08 cm(2). No dose-response to ANP was demonstrated, though respons es to the highest dose differed significantly from those to the lowest dose studied. We conclude that human cutaneous responses to ANP diffe r from those of animals and that the skin is less responsive than othe r tissues in humans.