Robinson N A, Pace J G, Matson C F, Miura G A, Lawrence W B
Pathophysiology Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, Maryland.
J Pharmacol Exp Ther. 1991 Jan;256(1):176-82.
The distribution, excretion and hepatic metabolism of [3H]microcystin-LR (sublethal i.v.) were measured in mice. Plasma elimination was biexponential with alpha- and beta-phase half-lives of 0.8 and 6.9 min, respectively. At 60 min, liver contained 67 +/- 4% of dose. Through the 6-day study the amount of hepatic radioactivity did not change whereas 23.7 +/- 1.7% of the dose was excreted; 9.2 +/- 1.0% in urine and 14.5 +/- 1.1% in feces. Approximately 60% of the urine and fecal radiolabel 6 and 12 hr postinjection was the parent toxin. Hepatic cytosol, which contained 70 +/- 2% of the hepatic radiolabel (1 hr through 6 days), was prepared for high-performance liquid chromatography analysis by heat denaturation, pronase digestion and C18 Sep Pak extraction. At 1 hr, 35 +/- 2% of the radiolabel was insoluble or C18 Sep Pak-bound; 43 +/- 3% was associated with a peak of retention time (rt) 6.6 min, and 16 +/- 3% with the parent toxin (rt 9.4 min). After 6 days, 8 +/- 1% was C18 Sep Pak-bound or insoluble; 5 +/- 0% occurred at rt 6.6 min, 17 +/- 1% with parent and 60 +/- 2% was associated with rt 8.1 min. Two other peaks, rt 4.9 and 5.6 min, appeared transiently. Analysis of hepatic cytosol by desalting chromatography under nondenaturing and denaturing conditions revealed that all of the radiolabel was associated with cytosolic components, and 83 +/- 5% was bound covalently through 1 day. By day 6 the amount of covalently bound isotope decreased to 42 +/- 11%. This is the first study to describe the long-term hepatic retention of microcystin toxin and documents putative detoxication products.
对小鼠静脉注射亚致死剂量的[3H]微囊藻毒素-LR后，测定了其在小鼠体内的分布、排泄及肝脏代谢情况。血浆消除呈双指数型，α相和β相半衰期分别为0.8分钟和6.9分钟。60分钟时，肝脏中含有的剂量为67±4%。在为期6天的研究中，肝脏放射性物质的量未发生变化，而23.7±1.7%的剂量被排泄；9.2±1.0%经尿液排泄，14.5±1.1%经粪便排泄。注射后6小时和12小时，尿液和粪便中放射性标记物的约60%为母体毒素。肝脏胞质溶胶含有肝脏放射性标记物的70±2%（从1小时到6天），通过热变性、链霉蛋白酶消化和C18 Sep Pak萃取制备用于高效液相色谱分析。1小时时，35±2%的放射性标记物不溶或与C18 Sep Pak结合；43±3%与保留时间（rt）6.6分钟的峰相关，16±3%与母体毒素（rt 9.4分钟）相关。6天后，8±1%与C18 Sep Pak结合或不溶；5±0%出现在rt 6.6分钟，17±1%与母体相关，60±2%与rt 8.1分钟相关。另外两个峰，rt 4.9和5.6分钟，短暂出现。在非变性和变性条件下通过脱盐色谱法对肝脏胞质溶胶进行分析表明，所有放射性标记物都与胞质溶胶成分相关，并且在1天内83±5%通过共价结合。到第6天时，共价结合的同位素量降至42±11%。这是第一项描述微囊藻毒素毒素在肝脏中长期滞留情况并记录假定解毒产物的研究。
