Circulation, Vol 77, 849-855, Copyright © 1988 by American Heart Association
M Volpe, N De Luca, MC Bigazzi, F Vecchione, G Lembo, M Condorelli and B Trimarco
Previous evidence suggests that atrial natriuretic factor (ANF) interferes
with the autonomic control of circulation. In the present study we
investigated whether ANF modulates forearm vasoconstriction reflexly
induced by cardiopulmonary receptor unloading in man. For this purpose, the
hemodynamic response to -20 mm Hg lower body negative pressure (LBNP) was
assessed under control conditions and during the constant infusion of
alpha-human ANF (0.5 micrograms/kg bolus followed by 0.05
micrograms/kg/min) in seven normal subjects. ANF infusion resulted in a
slight reduction in blood pressure and right atrial pressure, did not
modify heart rate or forearm vascular resistance, but significantly
potentiated the reflex increase in forearm vascular resistance during LBNP
(+25 +/- 9% under control conditions vs +40 +/- 12% during ANF, p less than
.05). In an attempt to clarify the mechanisms underlying the enhanced
reflex vasoconstriction during infusion of ANF, in five additional subjects
we demonstrated that there was a comparable vascular reflex response to
LBNP under control conditions and during nitroglycerin infusion at a dose
that induced a reduction in atrial pressure comparable to that observed
during ANF. Finally, in seven additional subjects we found that ANF
infusion did not alter the reflex hemodynamic responses elicited by carotid
baroreceptor unloading induced by a +60 mm Hg increase in external neck
pressure. We conclude that during the infusion of a pharmacologic dose of
ANF the reflex forearm vasoconstriction in response to selective
cardiopulmonary receptor unloading is potentiated. This effect does not
seem to be related to the hemodynamic actions of the peptide or to
interference with the sympathetic control of peripheral circulation.
ARTICLES
Atrial natriuretic factor potentiates forearm reflex vasoconstriction induced by cardiopulmonary receptor deactivation in man
Istituto di 1 Clinica Medica, 2 Facolta di Medicina, Universita di Napoli, Italy.
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