Receptor binding, cGMP stimulation and receptor desensitization by atrial natriuretic peptides in cultured A 10 vascular smooth muscle cells

AbstractReceptor characteristics for atrial natriuretic peptides (ANP) were demonstrated in the permanent tissue culture system of vascular smooth muscle cell (VSMC) line. 125I-ANP exhibited reversible and saturable binding to A10 rat VSMC, and the equilibrium dissociation constant, Kd was 157 pM and maximal binding capacity, .Bmax amounted to 115 fmolmg of protein. Binding of the 125I-ligand was highly specific for certain potently displacing ANP analogues with inhibition constants (Ki values) in the nano- or even subnanomolar concentration range. Pretreatment of VSMC with ANP yielded receptor desensitization to one half of the ANP receptor density, and supports the conclusion of receptor autoregulation by ANP in A10 VSMC. The receptor coupled intracellular cGMP system was stimulated, and thus demonstrates the application of A10 cells as a model for the study of ANP receptor interaction involved in vascular smooth muscle relaxation