Respostas cardiovasculares à administração de Vitamina C no modelo de hipertensão renovascular experimental. / Cardiovascular effects in response to vitamin C administration in experimental renovascular hypertension model.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

An exaggerated production of reactive oxygen species (ROS) has been observed in different animal models of arterial hypertension (AH), among then the renovascular 2Kidney-1Clip (2K-1C) model. One of the purposes of the present Thesis was to evaluate if the endovenous (EV) administration of ascorbic acid (Vitamin C), an antioxidant, modifies the cardiovascular parameters and sympathetic activity in renovascular hypertension. Moreover, it is well known that in the renovascular hypertension model, the rostralventrolateral medulla (RVLM) is one of the most important nucleus involved in the cardiovascular control, its activity is fundamental for the tonic and reflex control of blood pressure and sympathetic nervous system (SNS) activity. In the present Thesis the Vitamin C was microinjected directly into the RVLM and the effects on mean arterial blood pressure (MAP), heart rate (HR) and renal sympathetic nerve activity (RSNA) were evaluated in the renovascular model. Finally, as it has a complex relationship among citokinas, NO and the sympathetic nerve activity (SNA) the expression of mRNA of neuronal nitric oxide synthase (nNOS) and interleukin-1 (IL-1) were analyzed in the brainstem tissue of the hypertensive animals. And to test if the Ang II is increased in this model it was quantified the expression of AT-1 subtype receptor in brainstem tissue. The acute treatment of Vitamin C in hypertensive rats produced a significant decrease in MAP after infusion, with no change in control rats during the period of observation. There was no change in heart rate (HR) in both groups. During the infusion there was a decrease in the frequency and amplitude RSNA only in hypertensive animals, the decrease in RSNA remains until the ending of the experiments. Bilateral microinjection of Vitamin C into the RVLM slowly decreased MAP in the hypertensive rats until 60 minutes. The response was accompanied by RSNA decreased without changes in HR. No changes were observed in normotensive rats.The hypertensive group showed significant increase in nNOS and decrease AT-1 and IL-1 expression when compared with control group. Therefore, it is suggested in the present Thesis that the oxidative stress acting central and periferically is involved in the renovascular hypertensive model (2K-1C).

ASSUNTO(S)

1. estresse oxidativo 4. hipertensão renovascular. 3. rvl farmacologia 2. vitamina c

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