Intracrine action of angiotensin II in the intact ventricle of the failing heart: angiotensin II changes cardiac excitability from within

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• 作者：Walmor C. De Mello (1) Walmor.de-mello@upr.edu
• 关键词：Failing heart &#8211 ; Intracellular injection &#8211 ; Angiotensin II &#8211 ; Action potential &#8211 ; Refractoriness
• 刊名：Molecular and Cellular Biochemistry
• 出版时间：December 2011
• 出版年：2011
• 期刊代码：38_03008177
• 类别：cp
• 卷：358
• 期：1-2
• 页码：309-315
• 数据来源：sp

摘要

The influence of intracellular injection of angiotensin II (Ang II) on electrical properties of single right ventricular fibers from the failing heart of cardiomyopathic hamsters (TO2) was investigated in the intact ventricle of 8-month-old animals. Intracellular injection was performed using pressure pulses (40&#8211;70 psi) for short periods of time (20 ms) while recoding the action potential simultaneously from the same fiber. The results indicated that intracellular Ang II caused a hyperpolarization of 7.7 mV 卤 4.3 mV (n = 39) (4 animals) (P < 0.05) followed by a small fall in membrane potential. The action potential duration was significantly increased at 50%and at 90%repolarization, and the refractoriness was significantly enhanced. The effect of intracellular Ang II on action potential duration was related to the inhibition of potassium conductance through PKC activation because Bis-1 (360 nM), a selective PKC inhibitor, abolished the effect of the peptide. Injections performed in different fibers of the same ventricle showed a variable effect of Ang II on action potential duration and generated spontaneous rhythmicity. The effect of intracellular Ang II on action potential duration and cardiac refractoriness remains for more than 1 h after interruption of the intracellular injection of the peptide.