These findings indicate that plasma BNP is more useful than ANP for assessing the mortality in patients with chronic CHF and that the plasma levels of BNP provide prognostic information independent of other variables previously associated with a poor prognosis. Our findings also suggest that the compensatory activity of the cardiac natriuretic peptide system is attenuated as mortality increases in chronic CHF patients with high plasma levels of ANP and BNP.
The main source of circulating endothelin-1 is not the peripheral vascular bed but the pulmonary vascular bed in patients with chronic heart failure. In addition, endothelin-1 secretion in the lungs may regulate the pulmonary vascular resistance in patients with chronic heart failure. These findings are consistent with a significant role for endogenous endothelin-1 in the pathophysiology of heart failure, especially in the pulmonary circulation.
BACKGROUND--Endothelin (ET)-1 is generated from big ET-1 by endothelin-converting enzyme (ECE). Plasma big ET-1 and ET-1 levels are strongly related to survival in patents with congestive heart failure (CHF). Because selective enzymatic processing of ET-1 formation appears to be an important therapeutic target for CHF, we investigated the acute effects of a specific ECE inhibitor on cardiorenal and endocrine functions in CHF compared with those of a selective ETA receptor antagonist. METHODS AND RESULTS--CHF was induced in beagle dogs by rapid right ventricular pacing (270 bpm, 14 days). Two incremental doses of a specific ECE inhibitor, FR901533, or a selective ETA receptor antagonist, FR139317 (1 and 3 mg/kg, n=8, respectively), were injected into dogs with CHF. FR901533 and FR139317 decreased mean arterial pressure and pulmonary capillary wedge pressure associated with reduction in systemic and pulmonary vascular resistance. These agents increased cardiac output but did not affect left ventricular fractional shortening. FR139317 exerted a greater depressor effect on mean arterial pressure than FR901533 (P<0.05). These agents decreased plasma atrial natriuretic peptide levels, but only FR901533 decreased plasma renin activity, angiotensin II, and aldosterone levels. Neither agent changed the plasma norepinephrine level despite the fall in blood pressure. These drugs increased the urinary water and sodium excretion rate associated with increases in the glomerular filtration rate and renal plasma flow, and the incremental magnitude induced by FR139317 was larger than that by FR901533 (P<0.05). CONCLUSIONS--An ETA receptor antagonist appeared to induce greater vasodilative effects on systemic and renal vasculature in CHF than an ECE inhibitor. However, the ECE inhibitor reduced the secretion of neurohumoral factors that are activated in proportion to the severity of CHF. Our acute complementary data may support the importance of the role of ECE in CHF and provide a rationale foundation for investigating the usefulness of long-term treatment with ECE inhibitors in CHF.
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