^125I—血管活性肠肽在小鼠体内的分布实验

为探讨高兹放活性血管活性肠肽（＾１２５Ｉ－ＶＩＰ）在正常小鼠体内的分布特性，取纯系昆明种小鼠３０只，随机分为６组，每组５只，在尾静脉注入＾１２５Ｉ－ＶＩＰ０．２ｍｌ（７４ｋＢｑ）后１８０分钟内的不同时相，将小鼠断头处死，收集血液、肺、肝、肠和肾，称重并测定其放射性，最后换算为每克组织的ＩＤ％。另取纯系昆明种小鼠３０只，分组同上，尾静脉分别注入含１０、２０和４０μｇＶＩＰ的＾１２５Ｉ－ＶＩＰ溶液，于

A biodistribution experiment on 125 I-VIP in mice]

This experiment was designed to investigate the biodistribution characters of 125 I-vasoactive intestinal peptide (VIP) with high specific activity in normal mice and the effect of VIP on the distributive test. After intravenous injection of 125 I-VIP, the mice were killed during 180 min. Blood, lungs, liver, intestine and kidneys were collected respectively and measured in 7 counter, finally the measurements of their radioactivity (cpm) were converted into ID%/g tissue and the results were expressed as mean+/-s. The effect on VIP on distributive test was evaluated by simultaneously injection of 125 I-VIP (74kBq) which contained 10,20 and 40 microgram VIP respectively; the mice were killed at 5 and 20 min. respectively, the collection of tissues and the management of data were the same as above. Most of the 125 I-VIP was distributed in the lungs rapidly, the radioactivity was mainly eliminated through kindneys; the T1/2 of activity in blood was shorter than 20 min; the difference in activity between liver and blood was not significant after 20 min. (P >0.05); the activity intestine remained lower during the experiment. The uptake of 125 I-VIP in lungs, liver and intestine was inhibited by VIP in dose dependence. The rates of inhibitory effectiveness of 10, 20 and 40 microgram VIP in lungs were 45.12%, 56.64% and 68.12% respectively at 5 min., and 53.65%, 71.03% and 79.03% respectively at 20 min. The present study indicated that the uptake of 125 I-VIP in various tissues of the mice possesses the character mediated by VIP receptor, 125 I-VIP is mainly accumulated by lungs, eliminated through kidneys, and the hepatobiliary system cannot remove it. The biodistribution character of 125 I-VIP is helpful to 131I (123I)-VIP imaging in the detection of gastrointestinal tumor.