Low-dose dopamine infusion increases baroreflex sensitivity by inhibition of peripheral chemoreflex

Abstract

Background: Inverse relation between reflex responses from arterial baroreceptors and peripheral chemoreceptors is well described phenomenon. It is unknown whether dopamine infusion by inhibiting afferent signalling from peripheral chemoreceptors would influence baroreflex sensitivity (BRS). Methods: We performed double-blinded, crossover, randomized and placebo-controlled study on 11 healthy male volunteers (median age 26 years). During low-dose dopamine (2 mcg/kg/min) and saline infusions all subjects underwent a BRS assessment with a non-invasive, sequential method and an assessment of peripheral chemosensitivity with transient hypoxic method. Hemodynamic response to hypoxia was measured non-invasively using Nexfin monitor and expressed as slopes relating changes in systolic blood pressure (SBP) and heart rate (HR) to changes in oxygen saturation. Results: Administration of low dose dopamine was associated with a significant reduction in peripheral chemosensitivity (median: 0.16 l/min/SpO2, [IQR 0.02-0.24] vs 0.40 l/min/SpO2 [IQR 0.26-1.49], p<0.005) with concomitant increase in BRS (1.42 bpm/mmHg, [IQR 1.17-1.99] vs 1.20 bpm/mmHg, [IQR 0.85-1.37], p<0.05) compared to saline. Dopamine infusion decreased SBP and HR slopes when compared to saline (0.33 mmHg/SpO2, IQR 0.27-0.53 vs 0.61 mmHg/SpO2, IQR 0.40-1.26, p=0.07; 0.44 bpm/SpO2, IQR 0.29-0.54 vs 0.56 bpm/SpO2, IQR 0.46-0.64 vs, p=0.07 respectively). Low-dose dopamine infusion did not change SBP comparing to saline infusion. Conclusion: Low-dose dopamine infusion has a beneficial effect on baroreflex sensitivity. We hypothesize that an increase in BRS is caused by concomitant attenuation of reflex response from peripheral chemoreceptors.