CHARACTERIZATION OF RENIN RELEASE FROM PARTIALLY PURIFIED RAT RENAL CORTICAL PLASMA MEMBRANES: EFFECTS OF TRYPSIN, HYPOPHYSECTOMY, SODIUM DEPRIVATION, CALCIUM AND OTHER IONS.
Item
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Title
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CHARACTERIZATION OF RENIN RELEASE FROM PARTIALLY PURIFIED RAT RENAL CORTICAL PLASMA MEMBRANES: EFFECTS OF TRYPSIN, HYPOPHYSECTOMY, SODIUM DEPRIVATION, CALCIUM AND OTHER IONS.
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Identifier
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AAI8801755
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identifier
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8801755
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Creator
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RUSSO, SHIRLEY MARIE.
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Contributor
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John C.S. Fray
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Date
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1987
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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, Animal Physiology
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Abstract
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A rat renal cortical cell suspension enriched in juxtaglomerular (JG) cells was used to facilitate the isolation of highly purified rat cortical plasma membrane vesicles (PMVs) using isotonic medium and Percoll self-forming gradient centrifugation. The cells exhibited normal stimulatory responses to forskolin, cAMP and ionomycin. The vesciles were characterized by enzyme markers, an ATPase vesicle sidedness and integrity assay, and electron microscopy. Contamination by mitochondria, lysosomes, granules, and ER membranes was minimal and the PMVs were of {dollar}>{dollar}85% inside-out orientation. Fifty percent of membrane-bound renin is in an inactive, but trypsin-activatable form. Other factors and maneuvers which are known to affect renin storage and secretion were investigated. For example, sodium deprived and hypophysectomized (Hx) rats had a higher renal renin content than controls. However, renin released from Hx rat kidneys was substantially lower than controls and sodium deprived, suggesting that the plasma membrane may be defective in releasing renin in the Hx rats and may store a large amount of renin. Supporting this hypothesis, renin specific activity of the PMVs was significantly greater in the sodium deprived and Hx rats which also had a high renal renin content compared to the normal controls. Lowering media Na caused a twofold increase in renin release from isolated PMVs whereas chloride was without effect. Neither EGTA nor calmodulin affected renin release from PMVs, but in combination they caused a substantial release with a subsequent decrease in membrane-bound renin. A dose dependent loss of renin specific activity in the extravesicular compartment (EVC), in part a function of media Ca, was observed below 140mM K, with a gain above 140mM K. These results support the hypothesis that the membrane plays a role in the storage and release, and perhaps in the uptake of renin. The advantages of this new PMV isolation method include the use of isotonic media throughout, a high proportion of vesicles with inside-out polarity, and a relatively short isolation time.
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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
