Influência da Angiotensina-(1-7) na sensibilidade colinérgica cardíaca de ratos normotensos e hipertensos
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2018-03-02
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Universidade Federal de Goiás
Resumo
Previous studies suggested that the Angiotensin-(1-7) [(Ang-(1-7)] is able to modulate the
cardiac sympathetic control and beta-adrenergic sensitivity. However, whether or not Ang-(1-
7) modulates the cholinergic activity in the heart remains unknown. The aim of this study was
to evaluate the influence of Ang-(1-7) upon cholinergic sensitivity of hearts from
normotensive and hypertensive rats. Wistar and Spontaneously Hypertensive Rats (SHR) were
anesthetized with urethane and underwent catheterization of femoral artery and left ventricle
to record the arterial and intraventricular pressure, respectively. Following, a dose-response
curve of acetylcholine (ACh, 10, 20, 40 and 80 ng/Kg, i.v. into femoral vein) was performed in
the absence or presence of Ang-(1-7) (7 x 10-12 mol/min), Mas receptor antagonist A-779 (7
x 10-11 mol/min) or Ang-(1-7)+A-779. Isolated hearts were perfused according to the
Langendorff technique. Increasing concentrations of ACh (10-7 to 10-5 mol/L) were added to
the hearts in absence or presence of Ang-(1-7), (2 x 10-11 mol/L), A-779, (2 x 10-10 mol/L),
Ang-(1-7)+A-779, MrgD receptor antagonist, D-PRO (2 x 10-10 mol/L) or D-PRO+Ang-(1-7).
ACh-induced vasorelaxation was assessed in absence or presence of Ang-(1-7) (2 x 10-11
mol/L or 2 x 10-10 mol/L). Ang-(1-7) attenuated the effect of ACh in decreasing the
intraventricular systolic, dP/dt max and dP/dt min in anesthetized Wistar and SHR. These
effects were blocked by A-779. Ang-(1-7) did not change the amplitude of the hypotensive
effect evoked by ACh in Wistar or SHRs. In isolated hearts, Ang-(1-7) also attenuated the
reduction of the intraventricular systolic pressure, dP/dt max and dP/dt min evoked by ACh.
A-779 blocked the Ang-(1-7) effects in hearts from Wistar. A-779 or D-PRO did not modify the
effects of Ang-(1-7) in hearts from SHR, but in presence of D-PRO, Ang-(1-7) effects were
equipotent. Ang-(1-7) attenuated the vasorelaxation induced by ACh in aorta from SHR by
only in SHR group. These data suggest that Ang-(1-7) exerts differential modulation of cardiac
cholinergic sensitivity during experimental primary hypertension, which is independent on
blood pressure.
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Citação
PONTES, C. N. R. Influência da Angiotensina-(1-7) na sensibilidade colinérgica cardíaca de ratos normotensos e hipertensos. 2018. 62 f. Dissertação (Mestrado em Ciências Biológicas) - Universidade Federal de Goiás, Goiânia, 2018.