J. Tamaoki et al., POTENTIATION OF BETA-ADRENERGIC FUNCTION BY SAIBOKU-TO AND BAKUMONDO-TO IN CANINE BRONCHIAL SMOOTH-MUSCLE, Japanese Journal of Pharmacology, 62(2), 1993, pp. 155-159
To determine the effects of the Kampo drugs Saiboku-to, Bakumondo-to a
nd Orengedoku-to on beta-adrenergic function in airway smooth muscle,
we studied isolated canine bronchial segments under isometric conditio
ns in vitro. Incubation of tissues with these drugs did not alter the
contractile responses to acetylcholine and histamine. The relaxation o
f tissues precontracted with acetylcholine induced by isoproterenol wa
s augmented by Saiboku-to and Bakumondo-to, so that the concentration
of isoproterenol required to produce a half-maximal effect (IC50) was
decreased from 4.6+/-0.5 x 10(-8) M to 1.9+/-1.0 x 10(-8) M (P<0.05) a
nd to 1.0+/-0.8 X 10(-8) M (P<0.01), respectively, whereas Orengedoku-
to had no effect. These effects were concentration-dependent with the
threshold concentrations being 0.3 mg/ml for Saiboku-to and 0.1 mg/ml
for Bakumondo-to. Saiboku-to and Bakumondo-to did not affect cyclic AM
P levels in airway smooth muscle per se but potentiated the isoprotere
nol-induced cyclic AMP accumulation. These results suggest that Saibok
u-to and Bakumondo-to but not Orengedoku-to potentiate beta-adrenergic
function in airway smooth muscle, which may reflect the efficacy of t
hese drugs on airway hyperresponsiveness and asthma.