Comparison of four different beta-adrenoceptor blocking drugs on lymphocyte isoprenaline-stimulated cyclic AMP...

1 The influence of acebutolol, atenolol, pindolol and timolol on human lymphocyte cyclic AMP (cAMP) and its stimulation by isoprenaline in vitro has been studied. 2 Acebutolol and atenolol (10(-8)-10(-6)M) had no significant influence on lymphocyte cAMP levels or on isoprenaline-stimulated increase in cAMP. 3 Pindolol and timolol significantly antagonised the effect of isoprenaline, and pA2 values were calculated to be 8.12 and 8.04 respectively. This suggests that beta 2-adrenoceptors are involved in this phenomenon. 4 Only pindolol produced a significant increase in lymphocyte cAMP, which is consistent with its partial agonist activity.