Enhanced Angiotensin II Activity in Heart FailureReevaluation of the Counterregulatory Hypothesis of Receptor Subtypes
作者:
Lionel Opie,
Michael Sack,
期刊:
Circulation Research: Journal of the American Heart Association
(OVID Available online 2001)
卷期:
Volume 88,
issue 7
页码: 654-658
ISSN:0009-7330
年代: 2001
出版商: OVID
关键词: angiotensin receptor subtypes;counterregulation;renin-angiotensin system;heart failure
数据来源: OVID
摘要:
There are strong data favoring the pathogenic role of angiotensin II type 1 receptor (AT1) activation with subsequent promotion of myocyte growth and cardiac fibrosis in the development of cardiac hypertrophy and heart failure. An emerging hypothesis suggests that the activity of the angiotensin II type 2 receptor (AT2) may counterregulate AT1receptor effects during cardiac development and during the evolution of cardiac hypertrophy and heart failure. In this review, we examine the potential role of AT2activity in the context of this hypothesis. In contrast to the counterregulatory hypothesis, studies in mice with an overabundance of, or a deficiency in, the AT2receptor do not suggest that AT2signaling is essential for cardiac development. Moreover, the proposed antigrowth effects of AT2receptor signaling in pathological cardiac hypertrophy could not be shown in two mice models both deficient in AT2receptors. The role of AT2receptor signaling in cardiac fibrosis is, however, still debatable because of conflicting data in the same two studies. In angiotensin II–evoked apoptosis in cardiomyocytes, the proposed proapoptotic role of AT2activity could not be confirmed. Furthermore, in the progression from the bench to bedside, the results of two large clinical trials in heart failure, namely ELITE II and Val-HeFT, can be explained without ascribing a major protective role to the unopposed activity of the AT2receptor in the failing myocardium. In this review, we conclude that the collective evidence does not strongly support a net beneficial effect of AT2stimulation in the diseased myocardium.
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