Developmental patterns of renal atrial natriuretic peptide receptors: [125I]alpha-rat atrial natriuretic peptide binding in glomeruli and inner medullary collecting tubules microdissected from kidneys of young rats.

The ontogenic developmental patterns of atrial natriuretic peptide (ANP) receptors of glomeruli and inner medullary collecting tubules (IMCT) were studied by measuring the specific binding of [125I]alpha-rat ANP 1-28 ([125I]alpha-RANP) to isolated glomeruli and IMCT microdissected from collagenase-treated kidneys of young rats aged from 2 to 35 days post-partum. For glomeruli and IMCT from young and adult animals, total and non-specific binding increased linearly with glomerulus number or tubular length. ANP receptors detected in glomeruli and IMCT from young rats showed the same stereospecifities as those from adult rats for recognition of ANP analogues (alpha-RANP 1-28, ANP 3-28, atriopeptin III and atriopeptin II). The numbers of ANP receptors in glomeruli and IMCT (expressed in terms of 10(-18) mol labelled ANP bound per glomerulus or per mm IMCT length, respectively) exhibited marked variations during postnatal ontogenesis; they were low after birth and rose progressively with age up to the corresponding adult levels (20 +/- 2 X 10(-18) mol.glom-1 and 4.4 +/- 0.8 X 10(-18) mol.mm-1) at the end of the 5th week of postnatal life.