[3H]ouabain binding to cultured rat vascular smooth muscle cells

• Published in: The American journal of physiology Vol. 246; no. 5 Pt 1; pp. C551 - C557
• Main Authors: Khalil, F, Hopp, L, Searle, B M, Tokushige, A, Tamura, H, Kino, M, Aviv, A
• Format: Journal Article
• Language: English
• Published: United States 01-05-1984
• Subjects: Animals; Binding, Competitive; Carotid Arteries - metabolism; Cells, Cultured; Kinetics; Male; Muscle, Smooth, Vascular - metabolism; Ouabain - metabolism; Rats; Rats, Inbred Strains; Receptors, Drug - metabolism; Sodium-Potassium-Exchanging ATPase - metabolism
• ISSN: 0002-9513
• DOI: 10.1152/ajpcell.1984.246.5.c551

The number of Na+ pump units (Bmax) and the equilibrium dissociation constant (Kd) for ouabain as well as parameters of K+ binding to the Na+ pump were examined in in vitro-grown vascular smooth muscle cells ( VSMC ) derived from Sprague-Dawley rats. The technique to measure these variables utilizes analyses of [3H]ouabain displacement from its VSMC receptors by nonlabeled ouabain and K+. The mean values for Bmax and Kd in the cultured VSMCs were 1.95 X 10(5) receptor sites per single VSMC and 2.68 X 10(-6) M, respectively. The equilibrium dissociation constant for K+ (Ki) was 0.92 mM. K+ binding to the cultured VSMCs demonstrated positive cooperativity with a Hill coefficient (n) of 1.78.