BINDING OF BETA(1)-ADRENOCEPTOR ANTAGONIST [H-3] CGP-26505 IN RAT CEREBRAL-CORTEX AND SINUS ATRIAL NODE

Specific beta(1)-adrenoceptors antagonist [H-3]CGP 26505 binding was c haracterized in rat cerebral cortex and heart sinus atrial node. In bo th tissues [H-3]CGP 26505 binding was maximal at 25 degrees C, it was specific, saturable and protein concentration dependent. Scatchard ana lysis of saturation isotherms of specific [H-3]CGP 26505 binding in ce rebral cortex showed that [H-3]CGP 26505 binds a single class of high affinity sites with a dissociation constant (K-D) of 1 +/- 0.3 nM and a maximal number of binding sites (B-max) of 40 +/- 2 fmol/mg of prote in. In sinus atrial node, [H-3]-CGP 26505 binds a single class of high affinity sites (K-D = 1.9 +/- 0.4 nM, B-max = 28 +/- 2 fmol/mg of pro tein).