The Journal of clinical investigation
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To investigate the physiological role of atrial natriuretic factor (ANF) in patients with hypoxic pulmonary hypertension secondary to chronic obstructive lung disease (COLD), we infused synthetic alpha-human ANF in seven such patients, and investigated the physiological correlates to circulating peptide levels in 24 patients with COLD. ANF infusion, at incremental rates of 0.01, 0.03, and 0.1 micrograms/kg.min, increased basal plasma immunoreactive (ir) ANF (136 +/- 38 pg/ml) by 3-, 10-, and 26-fold, respectively, and reduced pulmonary artery pressure (from 33 +/- 3 to 25 +/- 2 mmHg, P less than 0.001) and systemic arterial pressure (from 88 +/- 4 to 79 +/- 4 mmHg, P less than 0.001) in a dose-related fashion. Cardiac index increased by 13.5% (P less than 0.01) while heart rate was unchanged. ⋯ Plasma renin activity remained unchanged but aldosterone fell by 44% (P less than 0.01). The levels of plasma irANF in 24 patients correlated directly with the degree of hemoconcentration (r = 0.67, P less than 0.001), respiratory acidosis (r = -0.65, P less than 0.001), and pulmonary hypertension (r = 0.52, P less than 0.01). The results suggest that ANF may serve as a potent pulmonary vasodilator involved in the circulatory homeostasis of patients with COLD.