Diuretic and natriuretic properties of prestegane B, a mammalian lignan

The effect of increasing doses of prestegane B, a synthetic lignan, was examined in the anesthetized normal rat, using clearance methodology. Increasing doses of prestegane B 0.5, 1.0, 2.0, and 5.0 mg) were administered intravenously in our separate groups of hydropenic rats. Urine flow increased by 2.8 +/- 0.3, 4.5 +/- 0.5, 7.7 +/- 0.5, and 18.2 +/- 0.8 microliters/min, respectively, above control values. The rise of urinary sodium secretion was of similar magnitude and averaged 0.4 +/- 0.1, 0.8 +/- 0.2, 1.1 +/- 0.3, and 2.4 +/- 0.3 mu eq/min, respectively. No significant change in urinary phosphate excretion was obtained in all groups of rats, and glomerular filtration rate remained constant from control to experimental clearance periods. The natriuretic effect of prestegane B observed in this in vivo model could be related to the inhibition of the Na+-K+-adenosine triphosphate activity demonstrated in vitro in previous studies from our laboratory. The action of this substance is likely to be situated beyond the proximal tubule, since urinary phosphate was not altered. Prestegane B mimics the effects of other endogenous diuretic and natriuretic hormones, but its site of action and its effect on renal hemodynamics are obviously different.