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Mechanisms of angiotensin II recepto...

Lee, Sunghou.

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Mechanisms of angiotensin II receptor regulation.

紀錄類型:	書目-語言資料,印刷品 : Monograph/item
正題名/作者:	Mechanisms of angiotensin II receptor regulation./
作者:	Lee, Sunghou.
面頁冊數:	155 p.
附註:	Mentor: Kathryn L. Sandberg.
Contained By:	Dissertation Abstracts International62-05B.
標題:	Biology, Animal Physiology. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3016357
ISBN:	0493266089

Mechanisms of angiotensin II receptor regulation.
Lee, Sunghou.

Mechanisms of angiotensin II receptor regulation. - 155 p.

Mentor: Kathryn L. Sandberg.

Thesis (Ph.D.)--Georgetown University Medical Center, 2001.

Angiotensin receptor (AT) regulation was examined in renal medullary interstitial cells (RMIC); vascular smooth muscle cells (VSMC) isolated from 6 and 24 month old rats; and, an ovine model of left ventricular (LV) hypertrophy. AT1 receptors in RMIC were expressed at high levels when grown under iso-osmolar conditions. In contrast, hyperosmolar conditions, which mimicked the <italic> in vivo</italic> environment, caused a significant decrease in AT1 receptor expression. These data suggest that osmotic regulation of AT1 receptors alters interactions between Ang II and local vasoactive systems resulting in modulation of renal function under physiological conditions particularly, in the active regulation of the medullary osmotic gradient by RMIC located between the loops of Henle and vasa recta. AT1 receptors in VSCM from 24-month old rats were not down-regulated by cell growth to the same degree as in VSCM from 6 month old rats, suggesting that abnormal AT1 receptor regulation in aging VSMC may lead to the increased rate of proliferation and decreased elasticity and distensibility of aged vascular tissues observed <italic>in vivo</italic>. In both RMIC and VSMC, AT1 receptor regulation is controlled at the post-transcriptional level by RNA binding proteins that bind in the 5<super>′</super> leader sequence of the receptor mRNA and, which upon binding, inhibit AT1 receptor translation. In the sheep heart, the predominant AT receptor subtype is AT2. In a model of LV remodeling induced by anteroapical MI, AT2 receptor expression was up-regulated by the combination therapy of angiotensin converting enzyme inhibitors and AT1 receptor antagonists under conditions that significantly reduced LV remodeling compared to either treatment alone. These data suggest activation of AT2 receptors in myocardial tissue is cardioprotective and that the development of nonpeptide AT2 receptor agonists could have significant clinical utility in treating myocardial infarction and preventing LV remodeling. Taken together, these data suggest that AT receptors are dynamically regulated in a tissue-specific manner by physiological and pathophysiological factors including Ang II, which is generated from the local tissue renin-angiotensin system, in addition to the peripheral system.

ISBN: 0493266089Subjects--Topical Terms:

1017835
Biology, Animal Physiology.

Mechanisms of angiotensin II receptor regulation.
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520 $a Angiotensin receptor (AT) regulation was examined in renal medullary interstitial cells (RMIC); vascular smooth muscle cells (VSMC) isolated from 6 and 24 month old rats; and, an ovine model of left ventricular (LV) hypertrophy. AT1 receptors in RMIC were expressed at high levels when grown under iso-osmolar conditions. In contrast, hyperosmolar conditions, which mimicked the <italic> in vivo</italic> environment, caused a significant decrease in AT1 receptor expression. These data suggest that osmotic regulation of AT1 receptors alters interactions between Ang II and local vasoactive systems resulting in modulation of renal function under physiological conditions particularly, in the active regulation of the medullary osmotic gradient by RMIC located between the loops of Henle and vasa recta. AT1 receptors in VSCM from 24-month old rats were not down-regulated by cell growth to the same degree as in VSCM from 6 month old rats, suggesting that abnormal AT1 receptor regulation in aging VSMC may lead to the increased rate of proliferation and decreased elasticity and distensibility of aged vascular tissues observed <italic>in vivo</italic>. In both RMIC and VSMC, AT1 receptor regulation is controlled at the post-transcriptional level by RNA binding proteins that bind in the 5<super>′</super> leader sequence of the receptor mRNA and, which upon binding, inhibit AT1 receptor translation. In the sheep heart, the predominant AT receptor subtype is AT2. In a model of LV remodeling induced by anteroapical MI, AT2 receptor expression was up-regulated by the combination therapy of angiotensin converting enzyme inhibitors and AT1 receptor antagonists under conditions that significantly reduced LV remodeling compared to either treatment alone. These data suggest activation of AT2 receptors in myocardial tissue is cardioprotective and that the development of nonpeptide AT2 receptor agonists could have significant clinical utility in treating myocardial infarction and preventing LV remodeling. Taken together, these data suggest that AT receptors are dynamically regulated in a tissue-specific manner by physiological and pathophysiological factors including Ang II, which is generated from the local tissue renin-angiotensin system, in addition to the peripheral system.
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