Daly M J, Ou R, Gu X H, Casley D J, Nayler W G
Department of Medicine, University of Melbourne, Austin Hospital, Heidelberg, Vic., Australia.
J Mol Cell Cardiol. 1992 Dec;24(12):1433-41. doi: 10.1016/0022-2828(92)91084-i.
The binding characteristics of [125I]endothelin-1 (ET-1) to cardiac membranes isolated from rat hearts subjected to Ca(2+)-free perfusion or the Ca2+ paradox were examined. The effect of treatment with 2, 3 butanedione monoxime (BDM), which inhibits the tissue damage associated with the calcium paradox, was also investigated. Membranes from rat hearts perfused under control conditions bound [125I]ET-1 to a single population of sites with a Bmax of 107.7 +/- 3.7 fmol/mg protein and an affinity (KD) of 153 +/- 12 pM. Ten minutes of Ca(2+)-free perfusion resulted in a significant (P < 0.01) increase in Bmax to 167.5 +/- 8.3 fmol/mg protein without change in KD. Ca2+ repletion following Ca(2+)-free perfusion tended to increase further the Bmax (180.6 +/- 10.4 fmol/mg protein) without change in KD. Treatment with BDM attenuated but did not prevent the rise in Bmax following Ca(2+)-free perfusion. Following Ca2+ repletion, however, Bmax returned to control levels in the BDM treated group. These changes were not associated with changes in the ability of ET-1 and ET-3 to inhibit [125I]ET-1 binding. The results demonstrate that Ca(2+)-free perfusion is associated with an increase in the binding site density of [125I]ET-1 which is maintained or further increased upon Ca2+ repletion. If, however, the tissue damage associated with the Ca2+ paradox is prevented with BDM, Ca2+ repletion is associated with a reversal of the increase due to Ca(2+)-free perfusion.
研究了[125I]内皮素-1（ET-1）与从经历无钙灌注或钙反常的大鼠心脏分离的心肌膜的结合特性。还研究了用2,3-丁二酮单肟（BDM）处理的效果，该物质可抑制与钙反常相关的组织损伤。在对照条件下灌注的大鼠心脏的膜将[125I]ET-1结合到单一的位点群体，其最大结合容量（Bmax）为107.7±3.7 fmol/mg蛋白质，亲和力（KD）为153±12 pM。十分钟的无钙灌注导致Bmax显著（P<0.01）增加至167.5±8.3 fmol/mg蛋白质，而KD不变。无钙灌注后的钙补充倾向于进一步增加Bmax（180.6±10.4 fmol/mg蛋白质），而KD不变。用BDM处理可减弱但不能阻止无钙灌注后Bmax的升高。然而，在钙补充后，BDM处理组的Bmax恢复到对照水平。这些变化与ET-1和ET-3抑制[125I]ET-1结合的能力变化无关。结果表明，无钙灌注与[125I]ET-1结合位点密度的增加有关，在钙补充时该密度保持或进一步增加。然而，如果用BDM预防与钙反常相关的组织损伤，钙补充与无钙灌注引起的增加的逆转有关。
