- 作者: Samuel C.M Huang, Li-Der Hsiao, Chin-Sung Chien, Chuan-Chwan Wang, Chi-Tso Chiu, Ray J.F. Tsai, Chuen-Mao Yang
- 作者服務機構: Departments of Ophthalmology and Pharmacology ,College of Medicine, Chang Gung University Tao-Yuan, Taiwan, ROC
- 中文摘要: --
- 英文摘要: the BK-induced responses with dissociation constants of6.0-6.1. Pretreatment of CECs with pertussis toxin (PTX)or cholera toxin did not alter the BK-inducedlP accumu-lation. lncubation of CECs in the absence of external Caled to a significant attenuation of the IP accumulationinduced by BK. These results demonstrate that BK direct-1y stimulates phospholipase C-mediated signal transduc-tion through BK B receptors via a PTX-insensitive G pro-tein in canine CECs. This effect may function as the trans-ducing mechanism for BK-mediated cellular responses.The pharmacological properties of bradykinin (BK) re-ceptors were characterized in canine cultured cornealepithelial cells (CECs) using [ H]-BK as a radioligand.Analysis of binding isotherms gave an apparent equilib-rium dissociation constant of 0.34±0.07 nM and a maxi-mum receptor density of 179±23 fmol/mg protein. Nei-ther a B receptor-selective agonist (des-Arg -BK) norantagonist ([Leu , des-Arg ]-BK) significantly inhibited[ H]-BK binding to CECs, thus excluding the presence ofB receptors in canine CECs. The specific binding of [ H]-BK to CECs was inhibited by B receptor-selective ago-nists (BK and kallidin) and antagonists (Hoe 140 and [D-Arg , Hyp , Thi , D-Phe ]-BK),with a best fit using a one-binding-site model. The order of potency for the inhibi-tion of [ H]-BK binding was BK=Hoe 140>kallidin>[D-Arg , Hyp , Thi , D-Phe7]-BK. Stimulation of CECs byBK produced a concentration-dependent accumulationof inositol phosphates (IP) and an initial transient peak ofintracellular Ca . B2 receptor-selective antagonist ([D-Arg , Hyp , Thi , D-Phe7]-BK) significantly antagonized
- 中文關鍵字: --
- 英文關鍵字: Bradykinin receptor, Inositol phosphates, Ca2+, Pertussis toxin, Corneal epithelial cells