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New renin--angiotensin from plasma prorenin?
1Department of Physiology, University of Toronto, Ontario, Canada.
American Journal of Hypertension
|March 1, 1990
Summary
Nephrectomy increases extrarenal prorenin, while adrenalectomy enhances its conversion to renin. This suggests a circulating prorenin convertase, influenced by both kidneys and adrenal glands, plays a key role in regulating active renin levels.
Area of Science:
- Endocrinology
- Renal Physiology
- Biochemistry
Background:
- Plasma prorenin and renin levels are critical in blood pressure regulation.
- The sources and regulation of prorenin activation remain incompletely understood.
Purpose of the Study:
- To investigate the roles of nephrectomy and adrenalectomy on plasma prorenin and renin levels.
- To identify the presence and location of a prorenin convertase mechanism.
Main Methods:
- Rats underwent binephrectomy or adrenalectomy, with subsequent plasma analysis.
- Cross-circulation and in vitro blood mixing experiments were performed between nephrectomized and adrenalectomized rats.
- Monoclonal antibodies were used to characterize the newly formed renin.
Main Results:
- Binephrectomy increased plasma prorenin and decreased renin, suggesting abolished kidney convertase activity and stimulated extrarenal prorenin secretion.
- Adrenalectomy decreased prorenin and increased renin, indicating enhanced prorenin activation.
- Cross-circulation and in vitro experiments demonstrated a blood-borne prorenin convertase activity, primarily associated with renal function.
Conclusions:
- A secretory, extrarenal source of prorenin exists, stimulated by nephrectomy.
- A renal prorenin convertase mechanism, abolished by nephrectomy and stimulated by adrenalectomy, is present in the bloodstream.
- Active renin in high-renin states can originate from both direct renal release and activation of circulating prorenin.