The effects of l-, d- and dl-propranolol on antipyrine metabolism and isoprenaline-induced tachycardia were studied in rabbits. The plasma concentration of antipyrine was assayed by Brodie’s spectrophotometric method...The effects of l-, d- and dl-propranolol on antipyrine metabolism and isoprenaline-induced tachycardia were studied in rabbits. The plasma concentration of antipyrine was assayed by Brodie’s spectrophotometric method and the change of heart rate was evaluated by ECG. Both isomers of propranolol hydrochloride were administered iv （800 μg/kg） to the rabbits. d-propranolol produced an antipyrine t 1/2 of 2.67±0.77h and a cl of 0.49±0.1 l/h while its levo-form produced an antipyrine t 1/2 of 1.7±0.39h and a cl of 0.88±0.22 l/h. The differences between the half-lives and between the clearances were statistically significant （P【0.05 for t 1/2, P【0.01 for cl）. The inhibitory effects of l- and d-propranolol on isoprenaline-induced tachycardia were assessed. l-propranolol yielded an ID<sub>50</sub> which was only 1/88 of d-propranolol’s. Our studies showed that the β-receptor blocking activity of propranolol mainly came. from its levoform while the effect on antipyrine metabolism came from its dextro-form.展开更多
文摘The effects of l-, d- and dl-propranolol on antipyrine metabolism and isoprenaline-induced tachycardia were studied in rabbits. The plasma concentration of antipyrine was assayed by Brodie’s spectrophotometric method and the change of heart rate was evaluated by ECG. Both isomers of propranolol hydrochloride were administered iv （800 μg/kg） to the rabbits. d-propranolol produced an antipyrine t 1/2 of 2.67±0.77h and a cl of 0.49±0.1 l/h while its levo-form produced an antipyrine t 1/2 of 1.7±0.39h and a cl of 0.88±0.22 l/h. The differences between the half-lives and between the clearances were statistically significant （P【0.05 for t 1/2, P【0.01 for cl）. The inhibitory effects of l- and d-propranolol on isoprenaline-induced tachycardia were assessed. l-propranolol yielded an ID<sub>50</sub> which was only 1/88 of d-propranolol’s. Our studies showed that the β-receptor blocking activity of propranolol mainly came. from its levoform while the effect on antipyrine metabolism came from its dextro-form.
