Role of the renin-angiotensin system in the adaptation to high salt intake in immature rats.

The response of the renin-angiotensin system, extracellular fluid volume, plasma volume, plasma sodium and mean arterial blood pressure to an increase in salt intake (8% NaCl in the diet for 10 days) was compared in immature (20 days) and adult (80 days) rats which were either sham-operated or uninephrectomised. Salt feeding induced a significant increase in plasma sodium in immature animals, and a greater suppression of the renin-angiotensin system in immature than in adult rats, although extracellular fluid volume, plasma volume and blood pressure remained unchanged. Following uninephrectomy, however, the renin-angiotensin system was maximally suppressed in both age groups and in younger animals extracellular fluid volume, plasma volume and blood pressure were significantly increased.

The renin-angiotensin system in the perinatal period in rats.

Plasma concentrations of renin, angiotensinogen, kininogen, total protein, and renal renin concentration were measured in rats before spontaneous birth, immediately after vaginal delivery, during the subsequent 48 h, as well as at the ages of 10, 20 and 80 days. Preterm rats had a plasma renin concentration about 15 times higher than adults, which increased further in 1 h-old vaginally-delivered rats. Thereafter renin fell to very low levels within 2 h, rose again during the first day and remained at 4 times the adults level until day 10.

Effect of prolonged indomethacin therapy on renal function and selected vasoactive hormones in very-low-birth-weight infants with symptomatic patent ductus arteriosus.

Renal function and changes in the activity of selected vasoactive hormones during prolonged indomethacin therapy (1 week) were studied in 11 very-low-birth-weight infants with symptomatic patent ductus arteriosus. The initiation of indomethacin therapy was associated with a reduction in diuresis, a transient decrease in creatinine clearance, and an increase in body weight (P less than 0.01).

The effects of calcium and calcium-ionophores (X 537 A and A 23187) on renin release in the isolated perfused rat kidney.

1. Calcium depletion from the medium of the isolated perfused kidney reduced renin release and renal perfusate flow. 2.

Isorenin, pseudorenin, cathepsin D and renin. A comparative enzymatic study of angiotensin-forming enzymes.

1. Renin was purified 30 000-fold from rat kidneys by chromatography on DEAE-cellulose and SP-Sephadex, and by affinity chromatography on pepstatinyl-Sepharose. 2.