Immunohistochemical localization of atrial natriuretic peptide binding sites in juxtaglomerular cells and vascular walls of rat kidney

Since the kidney is one of the major sites of action for atrial natriuretic peptide (ANP) and immunoreactive ANP has been detected in tissue extract by radioimmunoassay, we have applied the immunohistochemical technique by using the avidin-biotin complex method to investigate ANP binding sites in the rat kidney. Although no immunostaining was observed in the kidney of control rats, immunoreactive ANP was present in the juxtaglomerular cells, the vascular walls of interlobular arteries, arcuate arteries, arterioles including vas afferens and vas efferens, and the medullary peritubular capillary of ANP-pretreated rats. In contrast, no tubular structure was stained. These results suggest that ANP may affect renin secretion via its direct action on the juxtaglomerular cells and that it predominantly induces natriuresis by its effects on renal hemodynamics.