Mortensen F V, Nielsen H, Mulvany M J, Hessov I
Department of Surgery, Aarhus County Hospital, Denmark.
Gut. 1990 Dec;31(12):1391-4. doi: 10.1136/gut.31.12.1391.
Colonic biopsy specimens were obtained from patients undergoing surgery for carcinoma of the rectum. Colonic resistance arteries (internal diameter 178-345 microns) were dissected out under the microscope and mounted in a microvascular myograph capable of measuring isometric tension development. Experiments were designed to test compounds trophic to the gastrointestinal tract--namely, glutamine and the three short chain fatty acids, acetic, propionic, and butyric acid, for effects on vascular tone. Glutamine in concentrations up to 30 mM neither constricted nor dilated the resistance arteries. The three short chain fatty acids alone and in combination, however, caused a concentration-dependent (range 0.1-30 mM) dilatation of resistance arteries preconstricted with 50 mM K+, and this relaxant effect was unaffected by removal of the endothelium, presence of indomethacin, and preconstriction with vasopressin. These data suggest that the trophic effect of glutamine on intestinal mucosa cannot be explained through actions of this compound on the resistance vasculature. In contrast, the relaxant effect of short chain fatty acids on resistance arteries in vitro suggests that these compounds may be able to improve the colonic microcirculation in vivo, thereby providing an explanation for their trophic effect on intestinal mucosa.
从接受直肠癌手术的患者身上获取结肠活检标本。在显微镜下解剖出结肠阻力动脉（内径178 - 345微米），并将其安装在能够测量等长张力变化的微血管肌动描记器中。实验旨在测试对胃肠道有营养作用的化合物——即谷氨酰胺和三种短链脂肪酸（乙酸、丙酸和丁酸）对血管张力的影响。浓度高达30 mM的谷氨酰胺既不使阻力动脉收缩也不使其扩张。然而，单独使用和联合使用这三种短链脂肪酸会导致预先用50 mM钾预收缩的阻力动脉出现浓度依赖性（范围0.1 - 30 mM）扩张，并且这种舒张作用不受内皮去除、吲哚美辛存在以及血管加压素预收缩的影响。这些数据表明，谷氨酰胺对肠黏膜的营养作用不能通过该化合物对阻力血管系统的作用来解释。相比之下，短链脂肪酸在体外对阻力动脉的舒张作用表明，这些化合物可能能够改善体内结肠微循环，从而为它们对肠黏膜的营养作用提供一种解释。
