| This study will observe the effects of baicalin on the isolated intestinal smooth muscle from rabbits and guinea pigs and its possible mechanism by using isolated smooth muscle methods. And effects of baicalin on the isolated bladder and gallbladder smooth muscle were studied at the same time.Baicalin (Final concentration 3×10-4M-3×10-3M) could decrease tension and amplitude of spontaneous contraction of the isolated ileum and descending colon from rabbits and descending colon from guinea pigs, but no effect on frequency of spontaneous contraction. In the isolated ileum from guinea pigs, baicalin could increase amplitude, tension and frequency first, then amplitude, tension and frequency of spontaneous contraction were decreased. Baicalin(Final concentration 10-5M-3×10-3M) could antagonism spasmodic contraction induced by acetylcholine(ACh), BaCl2 and high KC1 in the isolated ileum, descending colon, bladder and gall bladder smooth muscle from rabbits and guinea pigs. The mechanism of relaxation of baicain on intestinal smooth muscle was no relation with adrenergic receptor-mediated relaxation, cGMP-related relaxation and PG channel. But relaxation of baicalin on the isolated descending colon from rabbits was related with ATP-sensitive K+ channel. In relation with Ca2+, relaxation of baicalin on the isolated ileum and descending colon from rabbits which was similar with verapamil (an known Ca2+ antagonist) was associated with the inhibition of potential dependent channel(PDC) opened by KCl and release of Ca2+ from sarcoplasm reticulum induced by ACh and not related with receptor operated channel(ROC). Relaxation of baicalin on the isolated ileum and descending colon from guinea pigs which was not completely similar with verapamil was related with obstruction of PDC only, had no relation with release of Ca2+ from sarcoplasm reticulum and obstruction of ROC.In conclusion, baicalin can relax the isolated intestinal smooth muscle from rabbits and guinea pigs and can antagonism spasmodic contraction. Relaxation of baicalin is related with Ca2+, but is not completely similar in rabbit and guinea pig because of species variation. Baicalin can alleviate intestinal, gallbladder and bladder spasm and can be used to treat intestinal, gallbladder and bladder spasmodic disease. |
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