Baroreflex sensitivity impairment is associated with cardiac diastolic dysfunction in rats.

Abstract

BACKGROUND: Studies have shown that the autonomic dysfunction accompanied by impaired baroreflex sensitivity was associated with higher mortality. However, the influence of decreased baroreflex sensitivity on cardiac function, especially in diastolic function, is not well understood. This study evaluated the morphofunctional changes associated with baroreflex impairment induced by chronic sinoaortic denervation (SAD). METHODS AND RESULTS: Animals were divided into sinoaortic denervation (SAD) and control (C) groups. Baroreflex sensitivity was evaluated by tachycardic and bradycardic responses, induced by vasoactive drugs. Cardiac function was studied by echocardiography and by left ventricle (LV) catheterization. LV collagen content and the expression of regulatory proteins involved in intracellular Ca(2+) homeostasis were quantified. Results showed higher LV mass in SAD versus C animals. Furthermore, an increase in deceleration time of E-wave in the SAD versus the C group (2.14 ± 0.07 ms vs 1.78 ± 0.03 ms) was observed. LV end-diastolic pressure was increased and the minimum dP/dt was decreased in the SAD versus the C group (12 ± 1.5 mm Hg vs 5.3 ± 0.2 mm Hg and 7,422 ± 201 vs 4,999 ± 345 mm Hg/s, respectively). SERCA/NCX ratio was lower in SAD than in control rats. The same was verified in SERCA/PLB ratio. CONCLUSIONS: The results suggest that baroreflex dysfunction is associated with cardiac diastolic dysfunction independently of the presence of other risk factors.