Effects of Saiko-ka-ryukotsu-borei-to, a Japanese Kampo medicine, on tachycardia and central nervous system stimulation induced by theophylline in rats and mice

Effects of Saiko-ka-ryukotsu-borei-to (SRBT) on theophylline-induced tachycardia in anesthetized rats and theophylline-induced locomotion and convulsions in mice were examined. An intraduodenal administration of SRBT (1 g/kg) prevented theophylline (5 mg/kg, i.v.)-induced tachycardia in rats. SRBT also attenuated an increase in arterial blood pressure with a slow reduction in heart rate of rats treated with theophylline, with no influence on the plasma level of theophylline. However, SRBT did not change the beating rate of right atrium isolated from rats in the absence or presence of theophylline or isoproterenol. The locomotor activity of theophylline in mice was reduced by the treatment with SRBT. Furthermore, the latency of convulsions in mice induced by administration of theophylline at a higher dose (240 mg/kg, i.p.) was prolonged by treatment with SRBT (1 g/kg, p.o.) and seven out of fifteen mice were saved from death due to convulsions. These results suggest that theophylline-induced tachycardia and central nervous stimulation are suppressed by SRBT and that SRBT may reduce the undesirable actions of theophylline on the cardiovascular and central nervous systems.