Effect of dopamine on transient ventilatory response to exercise

Abstract

The effect of exogenous dopamine on the development of exercise hyperpnea was studied. Using a bicycle ergometer, five subjects performed repetitive square-wave work-load testing from unloaded pedaling to 80% of each subject's estimated anaerobic threshold. The breath-by-breath ventilation (VE), CO2 production (VCO2), and O2 consumption (VO2) responses were analyzed by curve fitting a first-order exponential model. Comparisons were made between control experiments and experiments with a 3-micrograms X kg-1 X min-1 intravenous infusion of dopamine. Steady-state VE, VCO2 and VO2 were unchanged by the dopamine infusion, both during unloaded pedaling and at the heavier work load. The time constants for the increase in VE (tau VE) and VCO2 (tau CO2) were significantly (P less than 0.05) slowed (tau VE = 56.5 +/- 16.4 s for control, and tau VE = 76.4 +/- 26.6 s for dopamine; tau CO2 = 51.5 +/- 10.6 s for control, and tau CO2 = 64.8 +/- 17.4 s for dopamine) (mean +/- SD), but the time constant for VO2 (tau O2) was not significantly affected (tau O2 = 27.5 +/- 11.7 s for control, and tau O2 = 31.0 +/- 10.1 s for dopamine). We conclude that ablation of carotid body chemosensitivity with dopamine slows the transient ventilatory response to exercise while leaving the steady-state response unaffected.

Role of the carotid bodies in the respiratory compensation for the metabolic acidosis of exercise in humans.

“…With inspirates of 30% 02, these authors could discern no peripheral chemoreceptor component, as evidenced by 'Dejours' tests (Dejours, 1963); in subsequent tests, however, in which the inspirate was 100% 02, there was a further significant slowing of the ventilatory kinetics -associated with a further slowing of VC02. The results of Linnarsson (1974) and Boetger & Ward (1986) are also consistent with this observation.…”

The effect of dopamine on pulmonary diffusing capacity and capillary blood volume responses to exercise in young healthy humans

“…Ventilation was significantly reduced in the dopamine condition 2 min into the time‐to‐exhaustion trials. This observation is similar to the work of Boetger and Ward (), which revealed that low‐dose dopamine appears to slow the transient ventilatory response to an increase in workload, but ultimately does not affect steady state ventilation. In addition, dopamine does not appear to affect peak exercise ventilation (Henson, Ward, & Whipp, ), which is consistent with the current investigation as we observed no difference in ventilation at end‐exercise.…”

Carotid chemoreceptor modulation of sympathetic vasoconstrictor outflow during exercise in healthy humans

“…Biscoe & Purves (1967) demonstrated, in anaesthetized animals, that passive exercise increased CC activity via feedback from the exercised limb, although subsequent studies failed to confirm this effect (Davies & Lahiri, 1973; Aggarwal et al 1976). Although the steady‐state ventilatory response to exercise seems to be unaffected by CC inhibition (Boetger & Ward, 1986; Henson et al 1992), the ventilatory kinetics to incremental exercise are slowed when chemoreceptors are inhibited with dopamine (Boetger & Ward, 1986). Thus, previous research suggests that the CCs are sensitized during exercise.…”