棉酚对大鼠^(42)K代谢影响的研究

A STUDY OF THE EFFECT OF GOSSYPOL ON THE METABOLISM OF ^(42)K IN RATS

本实验用同位素^(12)钾(^(42)KGl)示踪放射自显影定位以及定量测定方法研究棉酚对大鼠钾代谢的影响及其与低血钾的可能关系。动物连续喂服棉酚(剂量为5~10毫克/日/鼠)4-17周后按体重从舌下静脉注射50~100微居里^(42)KGl溶液。于注射后不同时距冷冻动物制成放射自显片观察,另取心、肾、骨骼肌、血和尿进行γ线闪烁定量测定。实验结果表明:(1)^(42)K注入体内后迅速与体内钾交换而摄入于脏器组织中,其中肾、心、脾、胰及胃肠道管壁出现放射活性高峰的时间最早,摄入速度最快。以下依次为软骨、肌肉、肝、皮下脂肪、肺、皮肤及睾丸,而以红细胞和脑脊组织的摄入速度最慢。血浆^(42)K的放射强度在注入体内30分钟后即降至较心、肾和肌肉为低的相对恒定水平。(2)大鼠服棉酚后,各脏器和血液中K的单位放射强度、摄入速度和分布动态,一般与对照组无明显差异,但肾脏的尿排^(42)K率则有增高倾向。其中少数动物在尿^(42)K排出率增高的同时,血浆和脏器^(42)K均明显下降。提示棉酚引起肾性失钾的可能性。本文对棉酚影响^(42)K代谢及引起肾性失钾的可能机理予以分析和讨论。

The present study was designed to investigate the effect of gossypol on the distribu tion kinetics and excretions of ^(42)K in rats by using autoradiographic and quantitative measurement techniques.After oral administration of gossypol to male rats at a dosage of 5~10 mg/day for 4~17 weeks,the animals were subjected to an intravenous(via vena sublingualis)injection of a dose of ^(42)K proportional to their body weight,and then one group of animals were anaesthetized and frozen in acetone cooled to-78℃with dry ice at varying time intervals after injection for whole-body and micro-autoradiographical observation;and another group the animals were killed at the same time intervals with samples of blood and tissues removed for analysis.It was found that the viscera take up ^(42)K rapidly after injection,among them the kidney,heart,spleen,pancreas,and the gastrointestinal tract appeared to be the earliest to reach their peak levels of radioactivity with their rapid uptake rates,next followed by cartilage,skeletal muscle,liver,adipose tissue,Lung,skin and testis the erythrocytes and brain tissues were took up most slowly.The plasma specific radioactivity decreased at about 30 minutes following injection to a level lower than that of the heart kidney and skeletal muscle,and thereafter maintained in a state of relative equilibrium.The pattern of distribution,kinetics and the uptake rates of ^(42)K radioactivity in viscera and blood of gossypol treated rats did not differ significantly from that of the controls.However,a tendency of somewhat higher excretion rates of urine ^(42)K in the gossypol treated rats was evident,among them a very small proportion of animals were found to be with loner ^(42)K activity in viscera and plasma concomitant with a higher rate of urine ^(42)K excretion.This phenomenon suggested the possibility that gossypol might induce renal potassium depletion.The effect of gossypol on potassium metabolism and the possible mechanism of renal 42K depletion induced by gossypol were analyzed and discussed.