as the morphological response to intracellular camp ( or its lipophilic derivatives ) is similar in both smc and fibroblasts , the difference in each cell line 's responsiveness to iso may be due to a difference in : ( 1 ) the density or sensitivity of beta-adrenergic receptors on the plasma membrane of each cell type , or ( 2 ) the catalytic activity of adenylate cyclase itself .
C0034785
beta-adrenergic receptors
C0007603
plasma membrane