| IntroductionEndothelin (ET) is peptide, which consists of 21 incomplete a-mino acid. It is by far known as the potent vasoconstrictor peptide with extensive biological effect. ET' molecular weight is 2492, and ET is a kind of multifunction adjustment peptide. It is a circulate or part hormone produced by blood vessel endothelial cell and it has function of contraction of blood vessel and increase blood pressure, and it is also a nerve transfer factor and adjustment peptide. ET takes part in the working of physiological function of many systems and the modulating of secretion of many hormones in the biological body. It is commonly recognized that ET may cause the function which is similar to the circulate hormone, and It causes the function of adjustment by side - secretion and self - secretion. ET plays an important role of the stability of the body. It not only has the function of adjustment for many tissue, and it not only work on the contraction of blood vessel, the dose - dependant function to the heart, and it also affects the release of the activated material of blood vessel and the contraction of blood vessel smooth muscle. In the isolated trachea and bronchia preparation of many kinds of animal, ET arouses the strong contraction. Different parts of smooth muscle have different sensitivity to ET. ET can excitethe smooth muscle of the gastrointestinal tract. Besides, It can also excite the smooth muscle of the isolated bladder, kidney calyx, sper-maduct, uterus, urine and procreation tract.The sphincter of Oddi is a ring smooth muscle, which is at the joint of the bottom of common bile duct and duodenum. The dysfunction may lead to the reverse flow of bile and pancreatic fluid, which plays an important role in the pathophysiologic process of many biliary and pancreatic diseases. Recent study shown that the dysfunction of SO has relationship with the abnormity of the nerve, the joint of biliary and pancreatic duct and the factor of incretion and body fluid . Reports of ET which is as a peptide hormone of gastrointestinal duct, on the effect of SO is rarely seen in the internal and international study in this field. So we first observe the effect of ET on the SO of isolated rabbit and ET antiserum further effect on the above effect. We hope that it will provide new method for the precaution , relief and treatment of the dysfunction of SO.Material and MethodPreparation of isolated rabbit sphincter of Oddi and force measurement .Rabbit ,10pcs,male or .female .weight at 3.0 -3. 5 KG. (supplied by the animal lab ). The rabbit is forbidden for food, but not for water for ten hours before the experiment . Rabbit was killed by a stunning , and was fixed on the rabbit operating table. After the hair is cleaned ,an upper median laparotomy was executed , then enter into the abodo-men. The SO was taken out immediately and placed into cold Krebs -Henseleit ( K - H) solution gassed with a mixture of 95% 02 and 5%CO2. After overlying fatty and connective tissues were dissected , the SO were cut into rings of 3 - 5mm width , which were mounted with two triangle self - made hooks vertically in an organ bath containing 10ml continuously gassed K - H solution at 37 ±0. 5℃. The tension of each SO ring was recorded with a pen recorder using a force displacement transducer attached to the upper end of it. An initial testing load of 1 g was applied to each SO ring , and the sensitivity degreeis 40 unit/lg . The speed of printing paper movement is 8mm/min . The solution above mentioned is changed for every 20 min, and the drugs were administrated after 60 - 90 min equilibration. In the period of e-quilibration, The 60mM KCL was added. Expressing the contraction as 100% , and it was the comparison of ET. When the rhythm contraction was occurred, different concentration of ET (0. InM -100nM) was added by cumulative ways and then observation of changes on the contraction frequency and swing of the SO was carried. The specimen was rinsed with new K - H solution for three times, after 60 min equilibratio...
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