an even larger down-regulation of beta-adrenoceptors and loss of receptor-stimulated adenylate cyclase activity was induced by the full endogenous agonist , noradrenaline , with the beta-adrenoceptors of heart muscle cells ( beta 1 ) being much more sensitive to the beta 1-selective noradrenaline than the heart non-muscle cell beta 2-adrenoceptors .
C0027061
of heart muscle
C0225828
heart