Abstract
Our aim was to investigate the differences in the duration of diuretic effects and impact on the renin-angiotensin-aldosterone (RAA) system of furosemide as a model of short- and long-acting loop diuretics. Anesthetized dogs (n=6) were randomized to placebo, intravenous bolus administration (IB), or chronic rate infusion (CRI) groups. This study was conducted with a crossover study. Furosemide (4 mg/kg) was diluted to 18 ml in sterile saline. Furosemide was infused at 0.5 mg/kg/hr for 8 hr in the CRI group or was injected at 0 and 4 hr (both 2 mg/kg) in the IB group. Blood and urine samples were collected at baseline, 1, 2, 4, 5, 6, and 8 hr. Compared to baseline, the IB group had significantly increased urine output at 1 and 5 hr. The CRI group had significantly increased urine output persisting for 4 hr compared to baseline. Compared to placebo, the 8-hr urine output and the 8-hr sodium excretion increased significantly in the IB and CRI groups; the values in the CRI group were significantly higher than those in the IB group. The 8-hr potassium excretion increased significantly in the IB and CRI groups. The plasma aldosterone concentration was significantly elevated in the IB group at 8hr. Duration of action may be a predominant cause of loop diuretic-related differences. Persistent diuresis may cause greater diuretic effects than transient diuresis, with less elevation of the plasma aldosterone concentration.
