[Hemodynamic and medicamentous modification of stimulated atrial natriuretic factor secretion]

The secretion of atrial natriuretic factor (ANF) and its adaptation to pharmacologic and hemodynamic interventions were investigated in 36 patients with sinus rhythm. To provoke standardized secretion of ANF all patients underwent two periods of rapid right ventricular pacing for 4 min with a 15 min interval. Immediately after the first pacing eight patients received 5 mg verapamil, 10 patients 5 mg atenolol and 10 patients 4 mg molsidomine intravenously. Eight patients remained untreated and served as controls. The amounts of atrial pressure increments due to pacing were identical (70% over basal pressure) in all patients. After molsidomine, but not after the other drugs, basal right atrial pressure was lowered. In controls the secretion of ANF due to the second stimulation was significantly (2.5-fold) larger than the secretion induced by the first stimulation. In patients receiving verapamil the secretion response after the second pacing was blunted. Atenolol did not affect the release of ANF. After molsidomine the upward regulation of the ANF secretion rate - seen in controls - was abolished. Thus, the myoendocrine cells are capable for a fast upward regulation of their ANF secretion rate after repeated stimuli. Verapamil directly blocks stimulated ANF secretion, whereas beta-blockade shows no effect. Molsidomine seems to impair enhanced ANF release by lowering basal atrial pressure.