Fig. 5. (A) The adenylate cyclase inhibitor 2',5'-dideoxyadenosine (DDA) reduces the percentage of apoptotic cells among ISO-treated hemocytes. (B) The protein kinase A inhibitor H-89 but not the protein kinase C inhibitors staurosporine (Stau) and calphostin C (CalC) reduce the percentage of apoptotic cells among ISO-treated hemocytes. These results indicate that adenylate cyclase and protein kinase A are required for the ß-adrenergic induction of apoptosis. Cells were maintained for 24 hours in the presence of 1 µM ISO or in the absence of drugs (Bas, basal level). Data are means and standard errors of three replicate experiments. Asterisks denote significant (P<0.01) differences from samples incubated in the presence of ISO alone.