Sul meccanismo dell'effetto antipertensivo del furosemide

Abstract Diuretics are antihypertensive drugs, because they lower the arterial pressure of hypertensive patients and have no effect on that of normal subjects. It is supposed that their antihypertensive effect is due to volume depletion; however, it could be more complex. In 17 patients with essential hypertension we have evaluated the arterial pressure before and during the administration of furosemide (1 mg/kg/day for 5 days), then after having restored the sodium and volume balance by the administration of saline solution (2,8 mEq/kg/day of Na for 5 days). In 4 patients we have measured the cardiac output (CO) and calculated the peripheral resistance (PR) before and after the 10 days of treatment. The mean arterial pressure decreased after the administration of furosemide (from 138,6 ± 15,5 to 116,0 ± 10,5 mmHg) and was still low after the sodium balance was restored to the initial value (120,2 ± 12,7 mmHg p < 0,001). In the cases where the haemodynamic changes were investigated, a 11,4% fall of mean arterial pressure (from 162,2 to 143,7 p < 0,01) was due in minor part to a decrease in CO (-3,0% n.s.) and more to a fall of PR (mean = -9,9% p< 0,05) while the plasma volume was unaltered (mean = + 1,5% n.s.). These data demonstrate that diuretics promote a haemodynamic rearrangement that is still present when saltvolume depletion is reequilibrated.