Regulation of atrial natriuretic peptide receptors in cultured vascular smooth muscle cells of rat.

To elucidate the regulation of vascular receptors for atrial natriuretic peptide (ANP), we have studied the binding capacity of 125I-labeled rat (r) ANP using cultured vascular smooth muscle cells from rat aorta. After preincubation with 3.2 X 10(-8) M rANP at 37 degrees C, the binding capacity decreased as a function of time; the maximal receptor loss (70-75%) occurred after 4 hrs and persisted for 24 hrs. Pretreatment with cycloheximide (20 micrograms/ml) and actinomycin D (2 micrograms/ml) similarly caused a dramatic reduction (approximately 80%) of the binding capacity after 24 hrs; the half-life (t1/2) of the receptor loss was approximately 7-8 hrs. Following removal of rANP, the "down-regulated" ANP receptors fully recovered in the presence of 10% fetal calf serum, but not in combination with either actinomycin D or cycloheximide. Concanavalin A dose-dependently inhibited the binding. The binding capacity also decreased with time in the presence of tunicamycin (1 microgram/ml) with t1/2 of approximately 30 hrs. These data indicate that protein and carbohydrate moieties are essential for the functional integrity of the vascular receptor binding sites for ANP, and suggest that the recovery of the receptor loss by "down-regulation" requires concomitant RNA and protein synthesis.