Potentiation of pressor response to angiotensin II at the preoptic area in spontaneously hypertensive rat |
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| Authors: | T Matsuda K Shibata M Abe M Tomonaga T Furukawa |
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| Affiliation: | 1. Centro de Ciências Sociais, Saúde e Tecnologia, Universidade Federal do Maranhão, Imperatriz, MA 65900-410, Brazil;2. Centro Brasileiro de Pesquisas Físicas, Rio de Janeiro, RJ 22290-180, Brazil;3. Instituto de Ciências Exatas e Naturais, Universidade Federal do Pará, Belém, PA 66075-110, Brazil;4. Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, SP 05508-900, Brazil;1. Department of Botany, Obafemi Awolowo University, Ile-Ife, BC220005 Nigeria;2. Department of Remote Sensing and GIS, Federal University of Technology, Akure, Nigeria;3. Department of Biology, Federal University of Technology, Owerri;4. Department of Geography, Obafemi Awolowo University, Ile-Ife, Nigeria |
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| Abstract: | Cardiovascular responses to angiotensin II(AII) at the preoptic area (POA) were compared between normotensive Wistar Kyoto rat (WKY) and spontaneously hypertensive rat(SHR) by measuring blood pressure and heart rate under unrestrained, conscious state via a catheter implanted chronically into the abdominal aorta and by injection of drugs into POA through a chronic guide cannula. AII injected into POA at doses of 0.3 ng and 1 ng produced a dose-dependent pressor response, accompanied with a slight decrease of heart rate, in both WKY and SHR. However, in SHR, the pressor response to AII was more than 2 times greater than that in WKY and was quick in onset and lasted about 30 min. When AII in combination with [Sar1, Ile8]-angiotensin II (0.5 microgram), an AII receptor antagonist, were simultaneously administered to POA, the pressor response to AII was strongly inhibited in both WKY and SHR. The results suggest that the pressor response to AII due to its receptor stimulation at POA is markedly potentiated in SHR. |
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