Kidney tubular epithelium cells and vascular smooth muscle cells contain different types of atrial natriuretic factor receptors

Abstract

We have identified and characterized three distinct atrial natriuretic factor (ANF) receptor subtypes from cultured canine kidney tubular (MDCK) cells and rat thoracic aortic smooth muscle cells. These are (1) a disulphide-linked 140-kDa protein found in rat thoracic aortic smooth muscle cells which was reduced by dithiothreitol to a 70-kDa band, (2) a disulphide-unlinked 120-kDa protein, specific to canine kidney tubular cells, whose molecular weight was not reduced by dithiothreitol and (3) a 66–70 kDa protein prevalent in both types of cell whose molecular weight was not reduced by dithiothreitol. The non-reducible 66–70 kDa and the reducible 140 kDa proteins showed strong affinities to the full-length ANF-(99–126) and truncated ANF-(103–123); however, the non-reducible 120-kDa protein showed strong affinity only to ANF-(99–126). Both ANF-(99–126) and ANF-(103–123) stimulated cyclic (c)GMP in the rat smooth muscle cells but only ANF-(99–126) stimulated cGMP in the canine tubular cells. Distinct ANF receptor subtypes might be linked to diverse physiological functions of ANF such as natriuresis and diuresis in kidney and vasorelaxation in vascular smooth muscle cells.