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Renin in the arterial wall.
Summary
Vascular walls possess renin-like activity, distinct from plasma renin. This aortic activity, not plasma levels, better predicts blood pressure responses, suggesting its crucial role in blood pressure regulation.
Area of Science:
- Biochemistry
- Physiology
- Cardiovascular Research
Background:
- Rat aortic wall homogenates exhibit renin-like activity, generating angiotensin I from plasma.
- This activity involves proteolytic enzymes and shows different pH optima compared to renal renin.
Purpose of the Study:
- To determine if aortic renin-like activity originates from plasma renin.
- To investigate the role of vascular renin-like activity in blood pressure control.
Main Methods:
- Altering plasma and aortic renin levels via bilateral nephrectomy and salt intake modulation.
- Studying four models of hypertension: Goldblatt 2-kidney 1-clip (early and chronic), DOC-salt, and spontaneous hypertension.
- Comparing pressor responses to injected renin with plasma and aortic renin activity levels.
Main Results:
- Aortic and plasma renin-like activities showed parallel changes under steady-state conditions.
- Acute renin injection revealed a shorter half-life for plasma renin than aortic renin.
- Pressor response to renin correlated more strongly with aortic renin activity than plasma renin activity.
Conclusions:
- Renin uptake by the arterial wall is a significant determinant of blood pressure.
- Evidence does not support local renin accumulation causing hypertension when plasma renin is normal or low.