Abstract
In the present study an attempt has been made to characterize the β-adrenoceptors of coronary vasculature in dog. Blockade of β1-adrenoceptors with ICI 50172 or β2-adrenoceptors with RB2 showed only partial antagonism of isoprenaline-induced decrease in coronary resistance. However, combined treatment with ICI 50172 and RB2 completely blocked the isoprenaline-induced fall in coronary resistance. Essentially similar results were observed in controlled heart rate experiments where the drugs were administered locally into the coronary circulation. These results demonstrate the involvement of both β1 and β2 adrenoccptors in isoprenalineinduced coronary vasodilatation.
