In a previous study (Circulation, 92:1-58,1995) we have shown that the baroreflex control of heart rate is significantly enhanced in rabbits with HF after administration of All (AT,) receptor antagonist. Because the control of heart rate is mediated by both sympathetic and parasympalhetic arms of autonomie nervous system we thought it necessary to investigate the role of All on the control of a pure sympathetic system in HF. Rabbits were instrumented so that we could record arterial and central venous pressure and paced for approximately 2 weeks at 360-380 bpm. A recording electrode was then placed on the left renal sympathetic nerve. Baroreflex curves were constructed in the conscious state approximately 3 days after electrode implantation. Curves were constructed before and after infusion of the AT! receptor antagonist L-158,809 (0.3 mg/kg). Unpaced rabbits were used as controls. Paced rabbits exhibited an increase in central venous pressure over control rabbits (8.3+1.3 vs. 1.1±0.4 mm Hg, respectively, p<.05>. Maximum baroreflex gain was reduced from 4.4+0.5 to 2.8+0.5 %/mm Hg (p<.05) in rabbits with HF. AT, blockade restored baroreflex sensitivity in HF rabbits (figure) but had no effect in normals. These data support the concept that All plays a role in baroreflex impairment in HF.
|Original language||English (US)|
|State||Published - Dec 1 1996|
ASJC Scopus subject areas
- Molecular Biology