In cardiac failure, efferent renal sympathetic nerve activity (ERSNA) and the activity of the renin-angiotensin system are increased, and arterial baroreflex regulation of ERSNA is attenuated. We examined the effect of intravenous and intracerebroventricular angiotensin II AT1 receptor blockade with losartan on the arterial baroreflex regulation of ERSNA in conscious control (C) and congestive heart failure (CHF) rats. Intravenous losartan (10 mg/kg, 21.7 μmol/kg) decreased arterial pressure more in CHF than in C rats (-28 ± 3 vs. -20 ± 3 mmHg, P < 0.05). After restoration of arterial pressure to the prelosartan value with methoxamine infusion, ERSNA was decreased more in CHF than in C rats (-23 ± 4 vs. -1 ± 2%, P < 0.05). Maximal gain of arterial baroreflex control of ERSNA (G(max)) was lower in CHF compared with C rats (-1.94 ± 0.10 vs. -3.78 ± 0.21%/mmHg, P < 0.05). Intravenous losartan increased G(max) in CHF (to -3.01 ± 0.14%/mmHg, P < 0.05) but not in C rats (to -3.56 ± 0.19%/mmHg). Intracerebroventricular losartan (4.61 μg, 10 nmol) did not affect arterial pressure but decreased ERSNA more in CHF than in C rats (-13 ± 2 vs. -8 ± 3%, P < 0.05). Like intravenous losartan, intracerebroventricular losartan increased G(max) in CHF (from -2.11 ± 0.18 to -3.21 ± 0.30%/mmHg, P < 0.05) but not in C rats (from -3.98 ± 0.25 to -3.84 ± 0.22%/mmHg). These results suggest that increased activity of the renin-angiotensin system contributes to the increase in ERSNA and its abnormal arterial baroreflex regulation in cardiac failure.
|Original language||English (US)|
|Journal||American Journal of Physiology - Regulatory Integrative and Comparative Physiology|
|Issue number||5 38-5|
|State||Published - Jan 1 1995|
- renal sympathetic nerve activity
ASJC Scopus subject areas
- Physiology (medical)