Bar R S, Boes M, Dake B L, Sandra A, Bayne M, Cascieri M, Booth B A
V.A. Hospital, Iowa City, Iowa.
Endocrinology. 1990 Dec;127(6):3243-5. doi: 10.1210/endo-127-6-3243.
Perfused endothelial cell IGF binding proteins (ECBP) have been previously demonstrated to leave the microcirculation of the rat heart and distribute primarily in connective tissue elements of the heart. In the present study, ECBP have been crosslinked to IGF-I and the biologically inactive [1-27,gly4,38-70]-hlGF-I, an analog of IGF-I lacking the type I IGF receptor domain. The crosslinked ECBPs were perfused through the isolated rat heart and their tissue distributions determined. Both [ECBP-Analog] and [ECBP-IGF-I] left the microcirculation of the heart. [ECBP-Analog] preferentially localized in connective tissue elements with a muscle:connective tissue ratio of approximately 1:6, similar to the tissue distribution of perfused ECBP. In contrast, the [ECBP-IGF-I] complexes localized in cardiac muscle with a muscle to connective tissue ratio of approximately 3:1, virtually identical to the tissue distribution of IGF-I when the IGF-I is perfused through the heart in the absence of any binding proteins. We conclude that 1) ECBP in the presence of IGF will cross capillary boundaries and 2) the tissue distribution of [ECBP-IGF-I] is dictated by the IGF-I molecule.
先前已证实，灌注的内皮细胞胰岛素样生长因子结合蛋白（ECBP）会离开大鼠心脏的微循环，并主要分布在心脏的结缔组织成分中。在本研究中，ECBP已与胰岛素样生长因子-I（IGF-I）以及生物活性缺失的[1-27，gly4，38-70]-hlGF-I（一种缺乏I型IGF受体结构域的IGF-I类似物）交联。将交联后的ECBP灌注通过离体大鼠心脏，并确定其组织分布。[ECBP-类似物]和[ECBP-IGF-I]均离开心脏的微循环。[ECBP-类似物]优先定位于结缔组织成分中，肌肉与结缔组织的比例约为1:6，这与灌注的ECBP的组织分布相似。相比之下，[ECBP-IGF-I]复合物定位于心肌中，肌肉与结缔组织的比例约为3:1，这与在没有任何结合蛋白的情况下将IGF-I灌注通过心脏时IGF-I的组织分布几乎相同。我们得出结论：1）在存在IGF的情况下，ECBP会穿过毛细血管边界；2）[ECBP-IGF-I]的组织分布由IGF-I分子决定。
