Forgue-Lafitte M E, Kobari L, Gespach C, Chamblier M C, Rosselin G
Biochim Biophys Acta. 1984 Apr 10;798(2):192-8. doi: 10.1016/0304-4165(84)90303-9.
Physiological studies indicate that epidermal growth factor-urogastrone (EGF) acts on stomach epithelium as mitogen and modulator of acid secretion. Here, we studied the binding of 125I-EGF to gastric glands isolated from the guinea-pig fundus (acid-secreting part) and antrum. At 20 degrees C, the association of 125I-EGF to gastric glands was time-dependent (plateau at 90 min) and reversible (75-85% dissociation in 1 h). No degradation of the peptide was detected, but a time-dependent loss of binding capacity was observed. At apparent equilibrium (90 min, 20 degrees C) unlabelled EGF (80 pM to 80 nM) competed with 125I-EGF-binding in the same manner in antrum and fundus (50% inhibition, with 0.6 nM EGF). Whereas kinetics properties were similar in antrum and fundus, the binding capacity was 40-55% lower in fundus than in antrum in young animals (6-8 weeks). By contrast, in adult animals (20-30 weeks), binding was the same in both parts of stomach. Scatchard analysis showed that two orders of binding sites were present in all cases (Ki 0.34-0.47 nM, Ki 2.2-3.4 nM), and that the differences observed were only accounted for by number of binding sites. These results show that EGF possess high affinity binding sites on gastric epithelium. These sites, dependent upon the age of the animals, may be related to the modulations by EGF of gastric trophism and secretions.
生理学研究表明，表皮生长因子 - 尿抑胃素（EGF）作为有丝分裂原和胃酸分泌调节剂作用于胃上皮。在此，我们研究了¹²⁵I - EGF与从豚鼠胃底（泌酸部分）和胃窦分离的胃腺的结合情况。在20℃时，¹²⁵I - EGF与胃腺的结合是时间依赖性的（90分钟达到平台期）且可逆（1小时内解离75 - 85%）。未检测到肽的降解，但观察到结合能力随时间下降。在表观平衡状态（90分钟，20℃）下，未标记的EGF（80 pM至80 nM）在胃窦和胃底以相同方式与¹²⁵I - EGF结合竞争（50%抑制，0.6 nM EGF）。虽然胃窦和胃底的动力学特性相似，但在幼龄动物（6 - 8周）中，胃底的结合能力比胃窦低40 - 55%。相比之下，在成年动物（20 - 30周）中，胃的两个部分的结合情况相同。Scatchard分析表明，所有情况下均存在两类结合位点（Ki 0.34 - 0.47 nM，Ki 2.2 - 3.4 nM），观察到的差异仅由结合位点数量引起。这些结果表明，EGF在胃上皮上具有高亲和力结合位点。这些位点取决于动物的年龄，可能与EGF对胃营养和分泌的调节有关。
