Abstract 16538: Salt Loading in the Presesnce of Baroreflex Failure Predisposes to Pulmonary Edema in Spontaneously Hypertensive Rat
BACKGROUND: Patients with heart failure and preserved ejection fraction (HFpEF) are supersensitive to volume overload, and thus pulmonary edema. These patients have a high prevalence of severe arteriosclerosis, baroreflex dysfunction and salt-sensitive hypertension. Baroreflex is by definition regulates arterial pressure (AP), and also is a very powerful regulator of stressed blood volume. We recently demonstrated that deactivating the baroreflex results in striking volume intolerance. In the present study, we examined how baroreflex failure induced by sino-aortic denervation (SAD) and salt loading affect daily fluctuations of left atrial pressure (LAP) in hypertensive model rats.
Methods: We allocated freely moving 14 weeks old spontaneously hypertensive rats (SHR) (n=16) into 2 groups, SAD or sham operation (Sham). In the following week, we implanted a telemetry system to measure AP and LAP. One week after the second surgery, 2 groups were subjected to either normal (N-salt, 0.5% NaCl) or high salt diet (H-salt, 8% NaCl). We recorded AP and LAP a week after the initiation of N-salt or H-salt diet and generated histograms of LAP distribution for 24 hours.
Results: SAD did not increase AP (Sham/N-salt:150.6±7.6 vs. SAD/N-salt: 146.4±1.9 mmHg, NS, n=4 for each). However, H-salt increased AP both in Sham and SAD . In LAP histograms, SAD/H-salt increased mean LAP (SAD/H-salt:14.9±2.6 vs. Sham/N-salt: 11.4±1.6 mmHg, p<0.05, n=4 for each), significantly increased the standard deviations (Fig. 1), markedly widened the LAP distributions (Fig. 2) and strikingly prolonged the periods of LAP≧20 mmHg (Fig. 3) compared to other groups.
CONCLUSIONS: SAD with high salt intake strikingly increases LAP variations through the volume intolerance and frequently causes high LAP (20% of 24 hours) in SHR. These results strongly suggest that baroreflex failure would play a crucial role in the pathogenesis of pulmonary edema in patients with HFpEF.
- © 2013 by American Heart Association, Inc.