Evidence for a role of AT(2) receptors at the CVLM in the cardiovascular changes induced by low-intensity physical activity in renovascular hypertensive rats
| Autor: | Marcos Rodrigues, J.L.M. Rocha, Maria José Campagnole-Santos, Patrícia Maria Ferreira, Marcelo Eustáquio Silva, Andréia Carvalho Alzamora, Robson A.S. Santos, Raquel do Pilar Machado |
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| Rok vydání: | 2007 |
| Předmět: |
Bradycardia
medicine.medical_specialty Sympathetic Nervous System Microinjections Physiology Pyridines Physical exercise Blood Pressure Angiotensin II Type 2 Receptor Blockers Baroreflex Biochemistry Receptor Angiotensin Type 2 Renin-Angiotensin System Cellular and Molecular Neuroscience Endocrinology Heart Rate Internal medicine Physical Conditioning Animal Rats Inbred SHR Renin–angiotensin system Heart rate medicine Animals Receptor Neurons Medulla Oblongata business.industry Angiotensin II Imidazoles Rats Blood pressure Hypertension Renovascular cardiovascular system medicine.symptom business circulatory and respiratory physiology |
| Zdroj: | Peptides. 28(7) |
| ISSN: | 0196-9781 |
| Popis: | In the present study, we evaluated the involvement of the rennin-angiotensin system (RAS) in the control of the blood pressure (BP), baroreceptor-mediated bradycardia and the reactivity of caudal ventrolateral medulla (CVLM) neurons to Ang II and to AT(2) receptor antagonist in sedentary or trained renovascular hypertensive rats. Physical activity did not significantly change the baseline mean arterial pressure (MAP), heart rate (HR) or the sensitivity of the baroreflex bradycardia in normotensive Sham rats. However, in 2K1C hypertensive rats, physical activity induced a significant fall in baseline MAP and HR and produced an improvement of the baroreflex function (bradycardic component). The microinjections of Ang II into the CVLM produced similar decreases in MAP in all groups, Sham and 2K1C, sedentary and trained rats. The hypotensive effect of Ang II at the CVLM was blocked by previous microinjection of the AT(2) receptors antagonist, PD123319, in all groups of rats. Unexpectedly, microinjection of PD123319 at the CVLM produced a depressor effect in 2K1C sedentary that was attenuated in 2K1C trained rats. No significant changes in MAP were observed after PD123319 in Sham rats, sedentary or trained. These data showed that low-intensity physical activity is effective in lowering blood pressure and restoring the sensitivity of the baroreflex bradycardia, however these cardiovascular effects are not accompanied by changes in the responsiveness to Ang II at CVLM in normotensive or hypertensive, 2K1C rats. In addition, the blood pressure changes observed after AT(2) blockade in 2K1C rats suggest that hypertension may trigger an imbalance of AT(1)/AT(2) receptors at the CVLM that may be restored, at least in part, by low-intensity physical activity. |
| Databáze: | OpenAIRE |
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