Fig. 4.—
Time course of deoxyribonucleic acid (DNA) content in 16-human bronchial epithelium (16-HBE) cells in response to salbutamol (1×10−7 M, •), salbutamol (1×10−7 M) plus propranolol (1×10−5 M, ▪), forskolin (1×10−7 M, □), 8‐bromoadenosine 3′,5′-cyclic monophosphate (8‐Br-cAMP) (1×10−7 M, ▵), and 10% foetal bovine serum (▴). After a 72‐h incubation in serum-free medium to arrest cell growth, each drug was added and the cells were cultured for up to 48 h. In the control experiment, no drug was added (○). Data are shown as mean±sem; n=10 for each point. *: p<0.05, **: p<0.01, significantly different from control values; #: p<0.01, significantly different from corresponding values for salbutamol alone.