Abstract
Effects of trimebutine maleate (TM-906) on the spontaneous contraction were investigated in the isolated circular smooth muscle of the antrum region of the guinea pig stomach. TM-906 dose-dependently reduced the amplitude of the regular spontaneous contraction without any marked change in its frequency and basal tension. This effect of TM-906 was also observed in the presence of phentolamine, propranolol, atropine, and tetrodotoxin. However, the inhibitory effect of TM-906 was overcome by increasing the extracellular concentration of CaCl2. On the other hand, in preparations which exhibited irregular spontaneous contraction, TM-906 regularized it, and spontaneous contraction with regular frequency and amplitude was elicited. In addition, this regularizing effect of TM-906 was also observed in the presence of atropine and tetrodotoxin. It was concluded that TM-906 has dual effects on the spontaneous contraction, reducing the amplitude of regular contraction and regularizing the irregular contraction. These effects of TM-906 may be attributed to the direct action on the smooth muscle.
