Effect of Sodium on Blood Pressure Cardiac Hypert

Authors: Zhu Zhiming Zhu Shanjun Wu Ziqian Liu Daoyan Yang Yongjian Wang Xianmei Zhu Jijin Tepel Martin

Publish Date: 2004/01/01

Volume: 17, Issue: 1, Pages: 21-24

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Abstract

Zhiming Zhu Shanjun Zhu Ziqian Wu Daoyan Liu Yongjian Yang Xianmei Wang Jijin Zhu Martin Tepel Effect of Sodium on Blood Pressure Cardiac Hypertrophy and Angiotensin Receptor Expression in Rats American Journal of Hypertension Volume 17 Issue 1 January 2004 Pages 21–24 https//doiorg/101016/jamjhyper200308004Wistar rats were exposed to low and high sodium diet for 8 weeks Angiotensin II receptor mRNA abundance of p38 mitogenactivated protein kinase p38MAPK vasoconstriction of aortic rings and angiotensin IIinduced calcium increase were investigatedSeveral observations suggested that cardiac hypertrophy is dependent on pressure and volume overload1 High sodium intake has been shown to produce left ventricular hypertrophy23 Several mediators may contribute to the development of cardiac hypertrophy including angiotensin II Angiotensin II regulates electrolyte balance induces vasoconstriction and enhances blood pressure BP Angiotensin II is a potent vasoconstrictor and growth factor primarily acting through angiotensin II receptor type 1 AT1 receptor After binding of angiotensin II to the AT1 receptor several signaling pathways are activated45 Components of the stressresponsive signaling pathway p38 mitogenactivated protein kinase p38MAPK have been proposed to be involved in cardiac hypertrophic responses6The investigation conforms with the guide for the care and use of laboratory animals and was approved by the local ethics committee Male 7weekold Wistar rats weighing 200 to 250 g were used The rats were housed under a 12h/12h day/night cycle Rats were divided randomly into groups Rats were fed a high sodium diet 8 NaCl without n = 10 and with administration of nitrendipine 1 mg/kg/d n = 10 or a low sodium diet 08 NaCl n = 10 respectively Systolic BP tailcuff method and body weights were measured every week At the end of 8 weeks the rats were killed by decapitation and hearts and aorta were used for measurementsThe thoracic aorta was dissected carefully freed of connective tissue and placed in Krebs’ solution containing NaCl 120 mmol/L CaCl2 25 mmol/L KCl 56 mmol/L MgSO4 12 mmol/L NaHCO3 25 mmol/L NaH2PO4 12 mmol/L Dglucose 55 mmol/L equilibrated with 95 O2/5 CO2 pH 74 at 37°C Isometric force of the aortic ring was measured using a force transducer connected with a polygraph model AD Instrument Power Lab Australia The aortic rings were equilibrated for 60 min The resting tension was set to 2 g Angiotensin II 100 nmol/L were added and the contractions of the rings were measured

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