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), they 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 10-8M rANP at 370C, 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 μg/ml) and actinomycin D (2 μg/ml) similarly caused a dramatic reduction (∼ 80%) of the binding capacity after 24 hrs; the half-life (t/sub 1/2/) of the receptor loss was ∼ 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 μg/ml) with t/sub 1/2/ of ∼ 30 hrs