慢性摄入吗啡和U50488H对鼠心к-受体的影响

本研究观察了大鼠慢性摄入吗啡和U50488H对心脏κ-受体结合特性的影响。慢性吗啡处理9d后,大鼠对吗啡产生升温效应耐受性,同时心肌κ-受体的K_d和B_(max)均增加,提示慢性吗啡处理后心肌κ-受体数目上调,但亲和力降低。而慢性U50488H处理4d后即产生完全的降温效应耐受性,同时心肌κ-受体的K_d增加,B_(max)无明显改变,提示慢性U50488H处理后心肌κ-受体亲和力下降。结果表明,大鼠μ和κ阿片耐受引起心肌κ-受体的调节机制是不同的。

EFFECTS OF CHRONIC ADMINISTRATION OF MORPHINE AND U50488H ON THE CARDIAC K-RECEPTOR IN RATS

In the present study, the effects of, chronic morphine and U50488H treatment on the binding properties of cardiac K - receptor in the rats were determined. It was shown that, after chronic morphine treatment for 9 days, the rats developed tolerance to morphine as indicated by an attenuated hyperthermic response to morphine and both Kd and Bmas of cardiac k - receptor increased, indicating an increase in number of sites and a reduction in affinity to the k-ligand. After chronic U50488H treatment for 4 days, the rats developed tolerance to U50488H which was indicated by a decreased hypothermic response to U50488H and Kd increased, suggesting that the affinity to k-ligand decreased. The finding of the present study indicates that the regulatory mechanisms of cardiac k-receptor induced by the tolerance of μ-and k-opioid in rats are different.