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To investigate whether the response of atrial natriuretic factor (ANF) to volume expansion is impaired in the early stages of dilated cardiomyopathy, the effects of saline load (SL; 0.25 ml/kg.min for 120 min) were assessed in 12 patients with dilated cardiomyopathy and asymptomatic to mildly symptomatic heart failure (HF) and in nine normal subjects (N). SL increased plasma ANF levels in N (from 14.3 +/- 2 to 19.5 +/- 3 and 26 +/- 4 pg/ml, at 60 and 120 min, respectively, P less than 0.001), but not in HF (from 42.9 +/- 9 to 45.9 +/- 9 and 43.9 +/- 8 pg/ml). Left ventricular end-diastolic volume (LVEDV) and stroke volume were increased (P less than 0.001) by SL in N but not in HF. Urinary sodium excretion (UNaV) increased in N more than in HF during SL, whereas forearm vascular resistance (FVR) did not change in N and increased in HF (P less than 0.001). In five HF patients SL was performed during ANF infusion (50 ng/kg, 5 ng/kg.min) that increased ANF levels from 37.1 +/- 10 to 146 +/- 22 pg/ml. In this group, SL raised both LVEDV (P less than 0.01) and ANF (P less than 0.05), whereas FVR did not rise. In addition, the UNaV increase and renin and aldosterone suppressions by SL were more marked than those observed in HF under control conditions. Thus, in patients with dilated cardiomyopathy and mild cardiac dysfunction, plasma ANF levels are not increased by volume expansion as observed in N. The lack of ANF response is related to the impaired cardiac adaptations. The absence of an adequate increase of ANF levels may contribute to the abnormal responses of HF patients to saline load.

Background: Acute cardiac and cerebrovascular accidents are more frequent in hypertensive subjects with a family history of acute vascular accidents. The mechanisms underlying the susceptibility to vascular disease in these subjects are unknown. We investigated whether a parental history of premature heart attack or stroke in hypertensive subjects is associated with abnormalities of sodium handling., Methods and Results: Patients with mild, uncomplicated essential hypertension were divided into two subgroups according to family history: a subgroup with a parental history of premature heart attack or stroke (FV+, n = 18) and a subgroup with a family history completely negative for vascular accidents (FV-, n = 14). The two subgroups were comparable with respect to age, weight, sex distribution, blood pressure, duration of hypertension, cardiovascular risk factors, renal function, and organ damage. Baseline plasma renin activity (PRA), concentrations of aldosterone (PA), atrial natriuretic factor (ANF), and norepinephrine, and urinary electrolyte excretion were also comparable in the two subgroups. Despite these similarities, the responses to an acute saline load, measured under controlled metabolic and experimental conditions, were different in the two subgroups. In the FV+ subgroup at 60 minutes of saline load, PRA fell by 1.0 +/- 0.2 ng/ml/hr and PA concentration by 89.4 +/- 26 pg/ml and ANF concentration increased by 38 +/- 9 pg/ml, whereas in the FV- subgroup the corresponding responses were -2.3 +/- 0.3 ng/ml/hr (p less than 0.005), -190 +/- 43 pg/ml (p less than 0.05), and 80 +/- 13 pg/ml (p less than 0.005), respectively. Urinary sodium excretion was delayed in the FV+ subgroup (270 +/- 67 mu eq/min at 60 minutes) compared with the FV- subgroup (555 +/- 157 mu eq/min at 60 minutes, p less than 0.05). At 120 minutes of saline load, significant (p less than 0.005) differences in PRA and ANF concentration were still observed. In a control group of eight normal subjects the responses to a saline load were comparable to those in the FV- subgroup but greater than those in the FV+ subgroup at 60 minutes., Conclusions: These results provide evidence that the hormonal and renal adjustments to an acute salt load are impaired in hypertensive patients with a parental history of vascular accidents. We speculate that abnormalities of sodium handling may represent markers of a more rapid development of vascular injury in human hypertension.

The aim of this study was to highlight a different hormonal and hemodynamic pattern in patients with mild cardiomyopathy. For this purpose, we studied subjects with mild heart failure (CHF; NYHA class I and II; post-ischemic and idiopathic) who underwent an isotonic saline load (SL) (0.22 ml/kg/min of 0.9% NaCl for 120 min). A second group of age- and sex-matched normal subjects (C) was studied as a control. Basal hormonal and hemodynamic values of the 2 groups differed only in atrial natriuretic factor (ANF), left ventricular end-diastolic diameter and ejection fraction (EF). There were, on the contrary, no differences in basal plasma renin activity (PRA) and plasma aldosterone (PA) values. After SL, in C, percent changes in EF, cardiac output and ANF values were significantly higher than in CHF while total peripheral resistances increased only in CHF but not in C. In both groups there were decrements of PRA and PA, but these responses were significantly higher in C than in CHF. In conclusion, our results show that hormonal, renal and hemodynamic responses to salt/volume load are compromised in the early asymptomatic phase of heart failure. These abnormalities may predict the progressive deterioration of cardiac function, and may indicate appropriate therapeutic interventions since the early phases of the disease.

Previous studies demonstrate that high doses of angiotensin II (Ang II) increase the release of ANF from atrial cells but it is not known whether this is a direct effect of Ang II or due to the induced hemodynamic changes. We report the effects of low doses of Ang II (1, 2.5, 5, 10 ng/kg/min) in anesthetized, instrumented dogs after volume load (2.5% body weight) and converting enzyme inhibition. During Ang II infusion we found an increase in mean blood pressure (from 147 +/- 3 to 160 +/- 3 mmHg, p less than 0.05) and arterial ANF (from 32 +/- 6 to 80 +/- 23 fmol/ml, p less than 0.05), while left and right atrial pressures did not change significantly. In a second group of dogs (n = 4) that underwent a similar protocol with the infusion of vehicle alone we failed to find any statistical difference in the above mentioned parameters. The Ang II induced ANF release was not related to the hemodynamic changes. Changes in plasma ANF levels were, in turn, related to the effects of Ang II on hormones and kidney, thus suggesting a role for endogenous ANF. In a separate study we found an increase of ANF production (+129 +/- 18, +176 +/- 46, +210 +/- 66% basal value) from isolated atrial minces exposed to Ang II concentration of 1, 10, and 100 nM, respectively.