We investigated the effects of NKK-105 and its related drugs (Diisopropyl 4-hydroxy-1, 3-dithiolan 2-ylidene malonate: NKK-103, Diisopropyl 1, 3-dithiolan 2-ylidene malonate: NKK-100) on the bile-expelling mechanism in the isolated gall bladder, the isolated Oddi-sphincter and the isolated duodenum of guinea-pig and rabbit.
The results were as follows:
1) NKK-105 and its related drugs inhibited the spontaneous movement of Oddi-sphincter with a dose of over 1×10-6g/ml.
2) NKK-105 and its related drugs caused the inhibition of spontaneous movement and the relaxation and lowering of internal pressure in gall bladder of guinea-pig.
3) The pretreatment of NKK-105 and its related drugs slightly inhibited the acetylcholine (Ach) -induced contraction.
The inhibitory action of NKK-105 and its related drugs on the BaCl2 or Ach-induced contraction was more potent in the BaCl2 than in the Ach.
From these results, it suggested that relaxation by NKK-105 and its related drugs directly acted on the biliary system.
4) The inhibition of spontaneous movement and the relaxation of smooth muscles on the isolated biliary system increased in the order of NKK-100 <NKK-103 <NKK-105.
5) It seemed that relaxation of NKK-105 and its related drugs on the Oddi-sphincter accelerated to the expelling of bile into the duodenum.
