Autor(es):
Silva, Ana Quênia Gomes da ; Xavier, Carlos Henrique ; Santos, Maria Jose Campagnole ; Caligiorne, Sordaini M. ; Baltatu, Ovidiu C. ; Bader, Michael ; Santos, Robson Augusto S. ; Fontes, Marco Antônio P. ; Silva, Ana Quênia Gomes da ; Xavier, Carlos Henrique ; Santos, Maria Jose Campagnole ; Caligiorne, Sordaini M. ; Baltatu, Ovidiu C. ; Bader, Michael ; Santos, Robson Augusto S. ; Fontes, Marco Antônio P.
Data: 2014
Origem: Oasisbr
Assunto(s): Brain renin-angiotensin system; Sympathetic tone; Paraventricular nucleus; Transgenic rat
Descrição
Texto completo: acesso restrito. p. 101–110
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Previous evidence indicates that a balance between inhibitory gabaergic and excitatory angiotensinergic factors in the PVN is important for cardiovascular control. We investigated the cardiovascular response evoked from activation or blockade of GABAA receptors in the paraventricular nucleus (PVN), in transgenic rats with low brain angiotensinogen [TGR(ASrAOGEN)]. Brain Ang II and Ang-(1–7) levels were also determined. In functional experiments, TGR(ASrAOGEN) and Sprague–Dawley rats (SD, control) were anesthetized with urethane and blood pressure (BP), heart rate (HR) and renal sympathetic nerve activity (RSNA) were recorded. Brain Ang II and Ang-(1–7) levels were largely reduced in TGR(ASrAOGEN) compared with SD rats. Inhibition of PVN neurons with the GABAA agonist, muscimol (1 nmol/100 nL), resulted in an attenuated fall in all cardiovascular variables in TGR(ASrAOGEN) compared with SD rats. This difference was particularly pronounced in HR (TGR Mus − 23 ± 6 bpm vs. − 77 ± 9 bpm SD Mus; P < 0.05) and RSNA (TGR − 3 ± 10% vs.− 29 ± 8% SD; P < 0.05). Furthermore, the sympathetic response evoked by blockade of GABAA receptors in the PVN of TGR(ASrAOGEN) was also largely suppressed. The present data indicate that the sympathetic outflow mediated by PVN neurons under basal conditions is suppressed in TGR(ASrAOGEN) rats corroborating the functional significance of brain angiotensin production in the central regulation of sympathetic output to the cardiovascular system.
