Dobutamine potentiates arterial chemoreflex sensitivity in healthy normal humans

Abstract

β-Adrenergic agonists may increase chemosensitivity in humans. We tested the hypothesis that the β1-agonist dobutamine increases peripheral chemosensitivity in a double-blind placebo-controlled randomized and crossover study. In 15 healthy subjects, we examined the effects of dobutamine on breathing, hemodynamics, and sympathetic nerve activity (measured using microneurography) during normoxia, isocapnic hypoxia (10% O2), posthypoxic maximal voluntary end-expiratory apnea, hyperoxic hypercapnia, and cold pressor test (CPT). Dobutamine increased ventilation (7.5 ± 0.3 vs. 6.7 ± 0.2 l/min, P = 0.0004) during normoxia, markedly enhanced the ventilatory (16.1 ± 1.6 vs. 11.4 ± 0.7 l/min, P < 0.0001) and sympathetic (+403 ± 94 vs. +222 ± 5%, P < 0.03) responses at the fifth minute of isocapnic hypoxia, and enhanced the sympathetic response to the apnea performed after hypoxia (+501 ± 107% vs. +291 ± 38%, P < 0.05). No differences were observed between dobutamine and placebo on the responses to hyperoxic hypercapnia and CPT. Dobutamine increases ventilation during normoxia and potentiates the ventilatory and sympathetic responses to hypoxia in healthy subjects. Dobutamine does not affect the responses to hyperoxic hypercapnia and CPT. We conclude that dobutamine enhances peripheral chemosensitivity.