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Renin secretion in conscious Lyon hypertensive rats
S Bertolino1, C Julien, I A Medeiros
1Département de Physiologie et Pharmacologie Clinique, Centre National de la Recherche Scientifique ESA 5014, Faculté de Pharmacie, Lyon, France.
The American Journal of Physiology
|November 1, 1996
Summary
Lyon hypertensive rats exhibit altered renin secretion, with reduced responsiveness to blood pressure changes and beta-adrenoceptor stimulation. This suggests a complex regulation independent of angiotensin II feedback.
Area of Science:
- Cardiovascular Physiology
- Renal Physiology
- Hypertension Research
Background:
- The renin-angiotensin-aldosterone system (RAAS) plays a crucial role in blood pressure regulation.
- Dysregulation of renin secretion is implicated in the development and maintenance of hypertension.
- Lyon hypertensive (LH) rats serve as a genetic model for studying hypertension.
Purpose of the Study:
- To investigate the renin secretory profile in conscious, unrestrained Lyon hypertensive (LH) rats.
- To assess renin responses to reductions in mean arterial pressure (MAP) and beta-adrenoceptor stimulation.
- To explore the role of angiotensin II (ANG II) feedback in modulating renin secretion in LH rats.
Main Methods:
- Conscious, unrestrained LH and Lyon normotensive (LN) rats were studied under a normal-salt diet.
- Mean arterial pressure (MAP) was monitored, and plasma renin concentration (PRC) was measured under basal conditions, during stepwise MAP reduction, and during isoprenaline infusion.
- Angiotensin II AT1-receptor blockade with losartan was employed to assess feedback inhibition.
Main Results:
- LH rats displayed elevated MAP and significantly decreased basal plasma renin concentration and kidney renin content compared to LN rats.
- Pressure-dependent renin release occurred at lower MAP thresholds in LH rats, with similar sensitivity in the low-pressure range.
- Isoprenaline-induced renin secretion was significantly blunted in LH rats, an effect that persisted during losartan administration.
Conclusions:
- Renin secretion in LH rats is largely independent of MAP within its spontaneous variation range.
- The blunted renin response to beta-adrenoceptor stimulation in LH rats is not attributable to enhanced feedback inhibition by ANG II.
- These findings highlight intrinsic alterations in renin secretion regulation in this genetic model of hypertension.