Moderate exercise training reduces arterial chemoreceptor reflex drive in mild hypertension

The aim of our study was to check the responsiveness the chemoreceptor reflex in 28 young mildly hypertensive men (HTS), aged 18-32 years and 25 normotensive male subjects (NTS) aged 19-32 years, before and after 3-months dynamic exercise training. We tested the hypothesis that dynamic training reduces arterial chemoreceptor drive in mild hypertension. Circulatory response to 3-min hyperoxic inactivation of arterial chemoreceptors induced by 70% oxygen breathing was measured before and after training. Arterial blood pressure (BP) was recorded continuously by Finapres method, stroke volume and arm blood flow were registered by impedance reography, heart rate by ECG. Both groups were submitted to moderate 3-months dynamic exercise training. Before training the hyperoxic breathing caused in HTS a significant decrease in systolic BP by 6+/-1 mmHg p<0.01, in diastolic BP by 2+/-0.6 mmHg p<0.01, and in total peripheral vascular resistance (TPR) by 0.24+/-0.04 TPRU (p<0.01). After training hyperoxia augmented systolic BP by 2.64+/-1.9 mmHg (NS), diastolic BP by 2+/-1 mmHg p<0.05, and TPR by 0.043+/-0.05 TPRU (ANOVA). In NTS before training brief hyperoxia produced insignificant change in BP and TPR. In NTS after training hyperoxia increased systolic BP by 4.2 mm Hg+/-1.23 p<0.01 and diastolic BP by 3.1+/-0.6 mmHg p<0.01 respectively and TPR by 0.053+/-0.02 TPRU. Our results confirm earlier finding on the enhanced arterial chemoreceptor reflex drive in mild human hypertension. We conclude that normalizing arterial blood pressure in subjects with mild hypertension which occurred after 3-months dynamical exercise training is due to attenuation of the sympathoexcitatory chemoreceptor reflex drive by exercise training. The mechanism of this effect requires further study.