摘要
用在体方法研究电离辐射后大鼠小肠吸收酪氨酸(Tyr)的变化并对其机制进行了初步探讨。结果说明,以较低剂量6Gyγ线照射后第3天,出现暂时Tyr吸收障碍,以后很快恢复,并持续在正常水平。随照射剂量的增加,吸收障碍加重,3Gy以下照射,则不出现Tyr吸收障碍。6Gy照射后早期及不同剂量照射后第3天,肠上皮细胞计数及空肠和血浆的二胺氧化酶(DAO)活性变化与肠吸收Tyr的变化有较好的一致关系,表明肠上皮的损伤是引起照射后吸收障碍的原因之一。提示DAO活性也是能反映肠道辐射损伤的一个较敏感指标。实验还测定了小肠粘膜Na^+,K^+-ATP酶活性以及用加入葡萄糖后的小肠壁电位差和短路电流的增加幅度来判断Na^+的跨膜转运情况,说明Na^+,K^+-ATP酶活性下降及Na^+转运障碍也是引起肠吸收Tyr障碍的原因。
The absorption of L-tyrosine by the small intestine in normal and whole-body V-irra-diated rats and its mechanism were studied. The results showed that L-tyrosine absorption decreased temporarily after exposure to low dose such as 6 Gy, but recovered soon afterward and remained normal during the 30 days observation period after exposure, With increasing dose, the absorption of tyrosine reduced more severely. No influence on absorption was observed at doses below 3 Gy. Parallel changes were found between intestinal epithelial cell count and diamine oxidase (DAO) activity in jejunum and plasma during the early stage after exposure to 6 Gy and on the 3rd day after various doses, suggesting that the injury of intestinal epithelia was one of the causes of absorption obstacle, and that DAO activity appears to be a sensitive indicator for intestinal radiation injury. Measurements of Na+, K+-ATPase activity in the small intestinal mocosa and the potential difference (PD) and short circuit current (Iscc) of the intestinal wall suggested that decrease in Na,+K+ATPase activity and impairment of Na+ transport were also responsible for reduction of tyrosine absorption.
出处
《中国应用生理学杂志》
CAS
CSCD
1991年第1期48-53,共6页
Chinese Journal of Applied Physiology
关键词
电离辐射
酪氨酸
小肠
大鼠
irradiation
intestinal absorption
L-tyrosine
diamine oxidase
Na+, K+-ATPase
ionic transport
