Abstract
Summary
Exogenous erythropoietin (ESF) failed to influence indices of juxtaglomerular granules (JGI) or width of zona glomerulosa (ZGI) in normal rats or those subjected to hypoxia, unilateral renal artery constriction, or sodium depletion, stimuli associated with increased JGI and ZGI. Administration of renin, on the other hand, decreased JGI without reducing plasma ESF levels. These findings are interpreted as indirect evidence that the source of renal erythropoietin is not related to juxtaglomerular granules (JGG). Further, findings suggest that the increased JGI induced by hypoxia may be related to an increase in renal renin. Ultrastructural examination of JGG revealed their similar appearance in all situations suggesting that changes in JGI associated with various physiologic phenomena are most likely quantitative rather than qualitative.
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