| Autor: |
Bergamaschi CT; Federal University of São Paulo, School of Medicine, Rua Botucatu 862, 04023-060 São Paulo, SP, Brazil., Silva NF; Federal University of Espirito Santo, 29042-751 Vitória, ES, Brazil., Pires JG; UNIVIX Medical School, 29075-080 Vitória, ES, Brazil ; UNESC Medical School, 29703-900 Colatina, ES, Brazil., Campos RR; Federal University of São Paulo, School of Medicine, Rua Botucatu 862, 04023-060 São Paulo, SP, Brazil., Neto HA; Federal University of Espirito Santo, 29042-751 Vitória, ES, Brazil ; UNIVIX Medical School, 29075-080 Vitória, ES, Brazil ; EMESCAM Medical School, 29045-402 Vitória, ES, Brazil. |
| Abstrakt: |
The hypothesis that changes in neurotransmission within the rostral ventrolateral medulla (RVLM) are important to maintain the high blood pressure (BP) was tested in Goldblatt one kidney-one clip hypertension model (1K-1C). Male Wistar rats were anesthetized (urethane 1.2 g/kg, i.v.), and the effects of bilateral microinjections into the RVLM of the following drugs were measured in 1K-1C or control groups: glutamate (0.1 mol/L, 100 nL) and its antagonist kynurenic acid (0.02 mol/L, 100 nL), the angiotensin AT1 receptor antagonist candesartan (0.01 mol/L, 100 nL), and the nonselective 5-HT receptor antagonist methiothepin (0.06 mol/L, 100 nL). Experiments in 1K-1C rats were performed 6 weeks after surgery. In anesthetized rats glutamate response was larger in hypertensive than in normotensive rats (H: Δ67 ± 6.5; N: Δ43 ± 3.54 mmHg). In contrast, kynurenic acid microinjection into the RVLM did not cause any change in BP in either group. The blockade of either AT1 or 5-HT receptors within the RVLM decreased BP only in 1K-1C rats. A largest depressor response was caused by 5-HT receptor blockade. The data suggest that 5-HT and AT1 receptors act tonically to drive RVLM in 1K-1C rats, and these actions within RVLM contribute to the pathogenesis of this model of hypertension. |
