Characterization of [3H]Ryanodine Binding Sites in Smooth Muscle of Dog Mesentery Artery

The ryanodine receptor has been widely demonstrated to be a Ca2+ release channel in both skeletal and cardiac muscle. Ryanodine also functionally affects Ca2+ release from an intracellular pool of smooth muscle. In the present study, both high and low affinity ryanodine binding sites are identified in dog mesenteric artery (with Kd 5 nM and 269 nM, respectively). [3H]ryanodine binding is not correlated with the density of innervation in different smooth muscles. This study provides direct evidence of the presence of ryanodine binding sites in dog mesentery artery. These ryanodine binding sites are of smooth muscle origin.