消化管虚血性病変の成因に関する実験的研究

An Experimental Study of the Etiology of Ischemic Lesions in the Digestive Tract

　われわれはこれまで消化管，特に胃および腸管の虚血性病変について，いろいろな実験的研究を行ってきた．胃については，既に本誌¹⁾にも発表しているので，今回は大腸の虚血性病変の成因に関する実験的研究を中心に述べる．

　大腸の虚血性病変としては，虚血性大腸炎がよく知られており，欧米ではその実験的研究の発表も多い^2)～8)．一方，わが国でも最近注目されるようになり，臨床例の報告も増加してきた．そこでわれわれは，大腸の虚血性病変の病態および成因を追究するため，次の3つの実験モデル，すなわち①結腸動脈結紮による虚血性病変，②Gelfoam注入による虚血性病変，③血管内血栓形成による虚血性病変につき検討してみた．以下，それらについて具体的に述べる．

　Pathogenesis and etiology of ischemic lesions of the colon were studied experimentally in dogs in the following three manners: (1) ligature of the colic artery; (2) injection of Gelfoam (thrombus); and (3) formation of intravascular thrombosis. Ischemic lesions thus induced were investigated with the following results.

　1. Simple ligature of the colic artery did not yield much changes in the colon judged three days later.

　2. Combined ligature of the blood vessels brought about theoretically almost complete occlusion. Only then was seen segmental hemorrhage or erosion. Apparent ulcer formation was seen only in 1 out of 11 dogs.

　3. Vascular injection of Gelfoam colored by blue dye into the area of the descending colon resulted in a wide colored area 20.5 cm long and perforation was invariably found in all dogs. Injection into the area of the colon transversum resulted in perforation in 4 dogs out of 20, circumferential ulcer in 7, semicircular ulcer in 4 and small rounded ulcer in 2. Various patterns of ulceration were seen, closely resembling even histologically human ischemic colitis.

　4. Difference in the site of thrombus formation resulted in the different degree of ulceration: erosion or ulcer in the mucosa and submucosa; ulcer or perforation in the muscular layer; and perforation when occlusion reaches the serosa.

　5. Artificial thrombosis by the injection of sulfuric acid resulted in all five dogs in the formation of thrombus at the site of injection in the colonic artery. Intestinal lesions (multiple ulcers) were seen only in one dog. They were regarded as a result of minute thrombus in the mucosa.

　6. These results seemed to suggest that in the development of ischemic changes of the colon an important role be played by such a change as occlusion of minute vessels within the walls of the colon and not by a chief artery such as colonic artery.