Eckel J, Offermann A, Reinauer H
Basic Res Cardiol. 1982 May-Jun;77(3):323-32. doi: 10.1007/BF01908047.
Isolated muscle cells from adult rat heart have been used to study the effect of temperature and enzymic digestion on the binding of 125I-labelled insulin. Equilibrium binding studies were performed at both 4 and 37 degrees C, using insulin concentrations ranging from 2.5 X 10(-11) mol/l to 10(-6) mol/l. The empty site affinity constant decreased by 51% from 1.0 X 10(8) l/mol at 4 degrees C to 4.9 X 10(7) l/mol at 37 degrees C, whereas the total receptor concentration remained unaltered at both temperatures. The rate of dilution induced dissociation was enhanced by the presence of native insulin at 37 degrees C, confirming the presence of negative cooperativity among the receptor sites at physiological temperatures. Treatment of isolated heart cells with trypsin and beta-galactosidase led to a decrease in specific binding of 125I-labelled insulin. Myocytes treated with neuraminidase exhibited a significant increase in insulin binding, which was shown to be due to an increase in insulin-receptor affinity. These studies provide new information on the molecular characteristics of insulin receptors in the heart muscle.
成年大鼠心脏的分离肌肉细胞已被用于研究温度和酶消化对125I标记胰岛素结合的影响。在4℃和37℃下进行平衡结合研究，使用的胰岛素浓度范围为2.5×10⁻¹¹mol/L至10⁻⁶mol/L。空位点亲和常数从4℃时的1.0×10⁸L/mol下降51%至37℃时的4.9×10⁷L/mol，而总受体浓度在两个温度下均保持不变。在37℃时，天然胰岛素的存在增强了稀释诱导解离的速率，证实了生理温度下受体位点之间存在负协同性。用胰蛋白酶和β-半乳糖苷酶处理分离的心脏细胞导致125I标记胰岛素的特异性结合减少。用神经氨酸酶处理的心肌细胞表现出胰岛素结合显著增加，这表明是由于胰岛素-受体亲和力增加所致。这些研究为心肌中胰岛素受体的分子特征提供了新信息。
