Effects of Aldosterone on Urinary Kallikrein and Sodium Excretion during Fetal Life

Abstract

ABSTRACT. The present study was designed to investigate the effect of acute (2 h) and chronic aldosterone (4 days) infusion on urinary kallikrein excretion rate and on renal handling of Na+ and K+ in chronically catheterized fetal lambs e l 1 5 days gestation (n = 6) and >I25 days gestation (n = 7). Chronic aldosterone infusion decreased plasma renin activity in both groups of fetuses. Both acute and chronic aldosterone infusion produced significant decreases in UNa + V in fetuses >I25 days and in the majority of fetuses e l 1 5 days gestation (five of six). Aldosterone infusion did not increase K+ excretion in either group of fetuses. It is also demonstrated that chronic aldosterone infusion induced an increase in urinary kallikrein excretion rate in both groups of fetuses. Taken together, these results demonstrate that aldosterone has antinatriuretic but no kaliuretic effects during fetal life, but produces a rise in urinary kallikrein excretion rate during the last trimester of gestation in fetal lambs. (Pediatr Res 19: 1048-1052,1985 Abbreviations UKall, urinary kallikrein PRA, plasma renin activity HUK, human urinary kallikrein 'H-TAME, N-(p-tosy1)-1-arginine-PHI-methyl ester-hydrochlorideAldosterone acts on the kidney to increase sodium reabsorption in exchange for either potassium or hydrogen ion (I) and to stimulate renal kallikrein production (2). However, the role of aldosterone on the fetal renal function is not well defined. In respect to sodium metabolism, it has been shown that the percentage of filtered sodium excreted is elevated during fetal life (3,4) and in premature infants (5) suggesting a partial unresponsiveness of the distal nephron to aldosterone.On the other hand, it has been demonstrated that UKall excretion rate increases significantly during the last trimester of gestation in fetal lambs (6). Since this rise correlated with an increase in plasma aldosterone concentration, it was suggested that aldosterone may be an important modulator of renal kallikrein production during renal maturation (6).The present study was designed to explore in detail the effect of acute and chronic administration of aldosterone on UKall excretion rate during the last trimester of gestation in chronically Received April 5, 1985; accepted June 4, 1985 catheterized fetal lambs. Moreover, the quantitative relationship between plasma levels of aldosterone and renal handling of sodium and potassium was also evaluated. METHODSAnimal preparation and surgical procedures. The fetuses of 13 pregnant sheep of Dorset and Suffolk mixed breeding were studied. Six fetuses were between 99 and 107 days gestation (group I) and seven fetuses were between 125 and 13 1 days gestation (group 11) (term was 145 days) at the time of surgery. Gestational ages were based on the induced ovulation technique as described previously (7).Prior to surgery, the animals were fasted for 48 h. Anesthesia of the ewe and surgery of the fetus were performed as described previously (8). Briefly, the pregnant ewe was anesthetized using a mixture of...

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Renal Haemodynamic Effects of B2 Receptor Agonist Bradykinin and B2 Receptor Antagonist HOE 140 in Conscious Lambs

“…1997). Previous studies in rats and sheep have provided evidence that various components of the kallikrein-kinin system are developmentally regulated (Campbell et al 1968;Robillard et al 1985;Bascands et al 1996;El-Dahr et al 1997). For example, the rate of kinin formation in sheep plasma increases with age (Campbell et al…”

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