Developmental regulation of the alpha 1B-adrenoceptor in the sheep kidney

Abstract

The expression of renal alpha 1B-adrenoceptor (alpha 1B-AR) mRNA was studied and contrasted with the expression of renal renin mRNA in fetal and newborn sheep. Fetal sheep between 90 and 91, 116 and 118, and 139 and 141 d gestation (term is 145 d gestation) as well as newborn lambs between 1 and 2 d old and 8 and 10 d old were studied (n = 3 for each age range). The role of the renal nerves in regulating changes in alpha 1B-AR gene expression was also investigated by measuring renal cortical alpha 1B-AR mRNA levels and receptor kd and maximum number of binding sites in 24-h-old lambs that were either denervated (n = 6) or sham-operated (n = 5) 3 d before birth. During development, renal alpha 1B-AR mRNA levels show a marked increase in term fetuses; this increase persists into the first 2 d of life and is distinct from the developmental pattern seen for renal renin mRNA levels. Denervation of term fetuses does not alter the expression of renal alpha 1B-AR mRNA in newborn lambs when compared with sham-operated controls but decreases significantly the expression of the renin gene (p < 0.05). These results suggest that the alpha 1B-AR gene is developmentally regulated in the kidney in a pattern distinct from that seen for renin.(ABSTRACT TRUNCATED AT 250 WORDS)