Ontogeny of Isoproterenol-stimulated Renin Secretion from Sheep Renal Cortical Slices

The ontogeny of renin secretion from renal cortical slices was studied in two groups of fetal (107-109 days of gestation and 131-136 days of gestation; term is 145 days), newborn (3-9 days old), and adult nonpregnant sheep. Isoproterenol (ISO; 10(-8)-10(-5) M) significantly increased active renin secretion in all age groups (P less than 0.05), with newborns having the highest values at all concentrations. However, the percent changes in active renin secretion were similar among all ages. Inactive renin secretion also increased with ISO stimulation, with newborns having the highest rate of inactive renin secretion. The percent of total renin in the active form differed among ages, ranging at base line from 60 +/- 10% in fetuses at greater than 130 days of gestation to 88 +/- 6% in fetuses at less than 110 days of gestation (P less than 0.05). Propranolol (1 microM) inhibited ISO (10(-6) M)-stimulated active renin secretion at all ages. On the other hand, the prostaglandin (PG) synthase inhibitor aspirin (1.6 x 10(-5) M) did not inhibit ISO (10(-6) M)-mediated increases in active renin secretion in fetal (greater than 130 days of gestation) kidney slices and produced values intermediate between base line and ISO alone in newborns and adults.(ABSTRACT TRUNCATED AT 250 WORDS)