Developmental pattern of cyclic guanosine monophosphate production stimulated by atrial natriuretic peptide in glomeruli microdissected from kidneys of young rats

Abstract

Cyclic guanosine monophosphate (GMP) productions by alpha rat atrial natriuretic peptide 1-28 (alpha-rANP), carbamylcholine or sodium nitroprusside were assessed in isolated glomeruli microdissected from collagenase-treated kidneys of 2- to 34-day-old and adult rats. In both young and adult animals, alpha-rANP-stimulated cyclic GMP generation was proportional to the number of glomeruli and was enhanced in a dose-dependent and saturable fashion with increasing alpha-rANP concentrations. The apparent activation constant values were 6.4 nM for 5-day-old and 9.7 nM for adult rats. Maximal doses of either alpha-rANP or rANP 5-28 elicited similar responses in young and adult animals. Clear differences appeared between the developmental patterns of cyclic GMP productions stimulated by either alpha-rANP, carbamylcholine or sodium nitroprusside. The response to alpha-rANP was very large in the youngest rats tested, declined sharply during the suckling period and represented about 1.6 times the adult control level in 34-day-old rats. In contrast, the response to carbamylcholine was low after birth and rose progressively with age up to the adult level at the end of the weaning period, and the response to nitroprusside seemed to be independent of the animal's age.