Heart rate and arterial pressure variability in the experimental renovascular hypertension model in rats

The 1K1C group developed hypertension and tachycardia. The 1K1C group also presented reduction in variance as well as in LF (0.23 ± 0.1 vs. 1.32 ± 0.2 ms2) and HF (6.6 ± 0.49 vs. 15.1 ± 0.61 ms2) oscillations of pulse interval. Autoregressive spectral analysis of SAP showed that 1K1C rats had an increase in variance and LF band (13.3 ± 2.7 vs. 7.4 ± 1.01 mmHg2) in comparison with the sham group. The baroreflex gain was attenuated in the hypertensive 1K1C (− 1.83 ± 0.05 bpm/mmHg) rats in comparison with normotensive sham (− 3.23 ± 0.06 bpm/mmHg) rats. The autonomic blockade caused an increase in the intrinsic HR and sympathetic predominance on the basal HR of 1K1C rats. Overall, these data indicate that the tachycardia observed in the 1K1C group may be attributed to intrinsic cardiac mechanisms (increased intrinsic heart rate) and to a shift in the sympathovagal balance towards cardiac sympathetic over-activity and vagal suppression associated to depressed baroreflex sensitivity. Finally, the increase in the LF components of SAP also suggests an increase in sympathetic activity to peripheral vessels.