Bar R S, Boes M, Sandra A
Veterans Administration Hospital, Department of Internal Medicine, University of Iowa, Iowa City 52242.
Biochem Biophys Res Commun. 1988 Apr 15;152(1):93-8. doi: 10.1016/s0006-291x(88)80684-3.
Beating rat hearts were perfused with 125I-IGF-II alone or 125I-IGF-II and unlabeled IGF-II or insulin, then prepared for radioautography. Maximal 125I-IGF-II grain counts over capillaries were decreased in a dose-dependent manner by unlabeled IGF-II but were unaffected by coperfusion with insulin. To determine a potential role for capillary receptors in the transfer of circulating IGF to cardiac muscle, the effects of sequential loss of capillary IGF binding sites was determined. For IGF-I, loss of capillary binding sites by trypsin perfusion was accompanied by proportional decreases in the subsequent appearance of IGF-I in cardiac muscle. In contrast, similar decrements of capillary IGF-II binding did not affect muscle levels of IGF-II. We conclude that capillary endothelium of the intact heart possesses distinct IGF-I and IGF-II binding sites, with the capillary IGF-I binding sites being of potential importance in the transfer of vascular IGF-I to subendothelial cardiac muscle.
用125I-IGF-II单独灌注或125I-IGF-II与未标记的IGF-II或胰岛素共同灌注跳动的大鼠心脏，然后制备用于放射自显影。未标记的IGF-II以剂量依赖的方式降低了毛细血管上125I-IGF-II的最大颗粒计数，但与胰岛素共同灌注对其没有影响。为了确定毛细血管受体在循环IGF向心肌转移中的潜在作用，我们研究了毛细血管IGF结合位点顺序丧失的影响。对于IGF-I，通过胰蛋白酶灌注使毛细血管结合位点丧失，随后心肌中IGF-I的出现也相应减少。相比之下，毛细血管IGF-II结合的类似减少并不影响IGF-II的肌肉水平。我们得出结论，完整心脏的毛细血管内皮具有不同的IGF-I和IGF-II结合位点，毛细血管IGF-I结合位点在血管IGF-I向心内膜下心肌的转移中可能具有重要意义。
