Sympathetic overactivity in sinoaortic denervated C57BL mice

Abstract

Male C57BL mice were submitted to sinoaortic denervation (SAD), or sham surgery, implanted with catheters into femoral artery and jugular vein and let recover for 5 days. After basal recording of arterial pressure (AP) and pulse interval (PI) mice received cardiac autonomic receptor blockers methylatropine or propranolol (n=8–11 in each group). PI changes due to methylatropine or propranolol were measured as cardiac vagal and sympathetic tone, respectively. AP variability was calculated by standard deviation of successive values (SDNN) of systolic AP and PI variability determined by SDNN as well as by the square root of the mean squared differences of successive values of PI (RMSSD). Mean AP and SDNN of SAP was higher in SAD (149±3 and 10.0±0.5 mmHg) as compared to intact mice (136±2 and 6.5±0.4 mmHg). PI was similar between groups (104±3 vs 104±2 ms) while SDNN and RMSSD of PI were lower in SAD (5.4±0.7 and 2.0±0.2 ms) as compared to intact mice (8.2±0.8 and 2.7±0.3 ms). Atropine did not change PI of SAD (100±4 to 98±4 ms), while slightly decreased PI of control mice (103±2 to 96±2 ms, p<0.05). The increase in PI elicited by propranolol was marked higher in SAD (98±6 to 144±9 ms) than in intact mice (98±4 to 124±3 ms). Five days after SAD mice showed mild hypertension with marked increase in AP variability and cardiac sympathetic tone.Support: FAPESP, CNPq and CAPES.