ATRIAL-NATRIURETIC-PEPTIDE RECEPTORS IN GLOMERULAR CRYOSECTIONS OF RENAL MALIGNANT AND SPONTANEOUSLY HYPERTENSIVE RATS

ANP-receptors affinities (K-D) and capacities (B-max) were assayed in cryosections of glomeruli from 'malignant' hypertensive rats (2K-1C) a nd spontaneously hypertensive rats (PHR). Plasma ANP concentration was twofold higher in 2K-1C (P < 0.05) and PHR (P < 0.02) than in the res pective controls, K-D and B-max for rANP(99-126) and ANP(103-123) did not differ, ANP mediated cGAMP release in 2K-1C rats was also unaffect ed, AN P-C glomerular receptors (i,e, displacement of tracer binding w ith ANP(103-123)) were not down-regulated and had unchanged peptide bi nding affinity in either kidney of rats with 'malignant' hypertension and in PHR, The difference between B-max for rANP(99-126) and B-max fo r rANP(103-123) (ANP-A receptor binding) indicates moderate up-regulat ion of ANP-A receptors in the clipped, and down-regulation in the cont ralateral kidney of 2K-1C (2K-1C, right vs, left, P < 0.05). Since [AN P](pl), and also B-max and K-D for ANP were similar in both hypertensi on models investigated, changes of the [ANP](pl/)ANP-receptor system c an not completely explain the marked natriuresis of rats with 'maligna nt' hypertension.