Morriss F H, Crandell S S, Palma P A, Lichtenberger L M
Pediatr Res. 1984 Jun;18(6):528-31. doi: 10.1203/00006450-198406000-00009.
Infusion of gastrin, G-17I, at 0.4 microgram/min into either the maternal or fetal venous circulation of six late gestation sheep was associated with increases in serum gastrin concentration in the infused circulation and reciprocal decreases in the serum gastrin concentration in the other circulation (contraplacental) that perfused the placenta. Pentagastrin infusion at 0.4 microgram/min was associated with an increase in C-terminal specific gastrin immunoreactivity in both the infused and the contraplacental circulations. These observations suggest that biologically active fragments of gastrin, but not the intact molecule, may cross the ovine placenta. An alternative explanation for our results is that gastrin infusion into either the maternal or fetal circulation which perfuses the placenta may result in the release of an inhibitor (i.e., somatostatin) into the other circulation. Of broad importance, these observations indicate that although intact polypeptide hormones may not traverse the placenta, their concentrations in maternal and fetal sera may not be as independent as previously believed. Serum gastrin half-life values in late gestation sheep fetuses, lambs, and ewes were determined to be 13.7 +/- 1.9, 16.7 +/- 2.6, and 15.2 +/- 2.8 min, respectively. These similar values indicate that the relatively high serum gastrin concentrations observed in near-term sheep fetuses are not the result of prolonged half-life in the fetus.
以0.4微克/分钟的速率向6只妊娠晚期绵羊的母体或胎儿静脉循环中输注胃泌素G-17I，会导致输注循环中的血清胃泌素浓度升高，而灌注胎盘的另一循环（胎盘对侧）中的血清胃泌素浓度则相应降低。以0.4微克/分钟的速率输注五肽胃泌素，会使输注循环和胎盘对侧循环中的C末端特异性胃泌素免疫反应性均增加。这些观察结果表明，胃泌素的生物活性片段而非完整分子可能会穿过绵羊胎盘。对我们结果的另一种解释是，向灌注胎盘的母体或胎儿循环中输注胃泌素可能会导致另一个循环中释放出一种抑制剂（即生长抑素）。具有广泛重要性的是，这些观察结果表明，尽管完整的多肽激素可能不会穿过胎盘，但它们在母体和胎儿血清中的浓度可能并不像之前认为的那样相互独立。妊娠晚期绵羊胎儿、羔羊和母羊的血清胃泌素半衰期值分别测定为13.7±1.9分钟、16.7±2.6分钟和15.2±2.8分钟。这些相似的值表明，在近足月绵羊胎儿中观察到的相对较高的血清胃泌素浓度并非胎儿半衰期延长的结果。
