(890.4) Baroreceptor Deafferentation Impairs the Exercise Training -and Drug Treatment-Induced Adaptations in a Hypertensive Model of Menopause

Poster Board Number: E371

Maycon Ferreira (Universidade Federal de São Paulo (UNIFESP)), Gabriel Silva (Universidade Federal de São Paulo (UNIFESP)), Nathalia Bernardes (Universidade São Judas Tadeu (USJT)), Amanda Araujo (Universidade Federal de São Paulo (UNIFESP)), Danielle Dias (Universidade Federal de São Paulo (UNIFESP)), Maria Irigoyen (Instituto do Coração (InCor)), Kátia De Angelis (Universidade Federal de São Paulo (UNIFESP), Universidade Nove de Julho (UNINOVE))

Aim and Hypothesis: Here, we investigate the effect of SAD on physical and hemodynamic adaptations after long-term treatment with Enalapril and concurrent exercise training (CET) in a model of menopause. We hypothesized that the beneficial effects of exercise training combined with antihypertensive drug therapy would be reduced after the chronic absence of arterial baroreceptor reflex.

Methods: Female spontaneously hypertensive rats (90 days old) were distributed (7-8 animals/group) into ovariectomized groups: trained treated with E (OTE) and SAD trained treated with E (SAD-OTE). SAD procedure was performed at initial of protocol. Ovariectomy consisted of bilateral removal of the ovaries. Enalapril (3mg/kg) was administrated orally in drinking water. CET (40-60% maximal capacity) consisted of aerobic (motor treadmill) followed by resistance exercises (ladder adapted to rats), 3 days/wk for 8 weeks. Heart rate and BP variability were analyzed using signals of direct recording of BP. Vasopressor system was evaluated by sequential injection of a vasopressin receptor antagonist, losartan and hexamethonium.

Results: Treadmill performance was reduced in SAD group (plt;0.001). There were no differences for systolic, diastolic, and mean blood pressure (BP) between groups. SAD increased resting heart rate (plt;0.001). In addition, SAD-OTE group showed lower variance of pulse interval (ms²) (49.2±22.5 vs. OTE: 96.5±49.6), as well as higher systolic BP variance (mmHg²) (84.1±36.9 vs. OTE: 34.2±9.0) and low-frequency band (mmHg²) (11.2±4.9 vs. OTE: 6.5±3.4). BP reduction (mmHg) after vasopressin receptor antagonist (-20.5±10.5) and hexamethonium (-87.2±17.7) was higher in SAD-OTE (vs. OTE: -6.9±4.6 and -56.0±10.4, respectively).

Conclusion: Despite similar BP control, drug therapy-and training-induced adaptations are blunted in absence of baroreceptor deafferentation, suggesting that this mechanism play a crucial role to maintain physical and cardiovascular autonomic benefits.

Grant: FAPESP (2019/06277-0).