THE RENIN ANGIOTENSIN SYSTEM IN BULLFROGS AND MUDPUPPIES.
Item
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Title
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THE RENIN ANGIOTENSIN SYSTEM IN BULLFROGS AND MUDPUPPIES.
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Identifier
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AAI8302506
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identifier
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8302506
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Creator
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FRUCHTER, JOYCE.
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Contributor
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Carolyn Burdic | James A. Organ
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Date
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1982
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Language
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English
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Publisher
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City University of New York.
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Subject
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Biology, General
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Abstract
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The RAS (renin angiotensin system) has been characterized in two species of amphibians, in an anuran, the bullfrog (Rana catesbiana) an in an urodele, the mudpuppy (Necturus maculosus). As in mammals, ANG I (synthetic human angiotensin I) must be converted into an active form (presumably ANG II--synthetic human angiotensin II) in order for it to exert its pressor effects. Plasma angiotensinase activity was measured and shown to be less active than that of mammalian plasma angiotensinase. ANG II analogues were employed to study the pharmacological properties of receptors involved in ANG II action. {lcub}Sar('1), Ile('8){rcub}--ANG II did not conclusively inhibit the ANG II blood pressure effect in bullfrogs. At the test dose {lcub}Sar('1), Thr('8){rcub}--ANG II did inhibit the ANG II blood pressure effect but not completely. The cardiovascular and renal-vascular actions of angiotensins were also studied. It was shown that ANG I, ANG II, and bfANG (bullfrog angiotensin) all exert vasopressor responses in bullfrogs and mudpuppies. In vivo experiments showed that the pressor response to ANG II is largely mediated by catecholamines. In vitro large doses of ANG II increased the force of contraction of bullfrog helical arterial strips but the experiment did not support the hypothesis that this, too, is mediated by catecholamines. ANG II also increased the force of contraction of bullfrog and mudpuppy hearts which could be responsible at least in part for the vasopressor effect.;It was shown that ANG II affects bullfrog kidneys in the following manner. A low dose of ANG II produced antidiuresis, antinatriuresis, and antikaliuresis in vivo with no effect on average mean blood pressure or GFR (glomerular filtration rate) whereas a high dose produced diuresis, natriuresis, and kaliuresis. GFR and blood pressure were also significantly increased at the high dose. Constant pressure arterial perfusion of the kidney in situ resulted in antidiuresis, a decrease in GFR, and a decrease in outflow. This data supports the hypothesis that ANG II causes afferent arteriolar constriction.;The data in this thesis provide a framework for the continuation of the study of the RAS in amphibians.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
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Program
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Biology
