Krishnamra N, Limlomwongse L
Department of Physiology, Faculty of Science, Mahidol University, Bangkok, Thailand.
J Nutr Sci Vitaminol (Tokyo). 1995 Dec;41(6):687-97. doi: 10.3177/jnsv.41.687.
It has previously been proposed that the hypocalcemic action of gastrin was mediated by a gastric peptide gastrocalcin which enhanced bone uptake of calcium (Ca). The present study, thus, aimed to reconfirm the effect of gastrin on muscle and bone Ca uptake and to evaluate a possible direct effect of gastrin on tissue Ca uptake. First, we showed that human and rat gastrin (100 microgram /100 g body weight (bw), s.c.) acutely increased uptake of intragastrically administered 45 Ca by the tibia and femur. Interestingly, human gastrin was more effective and also enhanced 45 Ca uptake by the gastrocnemius muscle. In order to find out whether gastrin could act directly on bone, 10 microgram of rat gastrin /100 g bw and 45 Ca were injected into the right femoral artery supplying the right leg while the left leg received normal saline and an equal amount of 45 Ca. At 30 min, the right gastrocnemius muscle and femur were found to contain 168% and 162%, respectively, more 45 Ca than the left leg. In contrast, daily administration of 25 microgram of rat gastrins /100 g bw, s.c., for 2 weeks had no effect on muscle or bone total Ca content while the content of 45 Ca given on days 12 and 13 was lower in the tibia and femur of gastrin-treated rats. It could be concluded that gastrin transiently enhanced Ca uptake by muscle and bone. However, two-week treatment with gastrin appeared to accelerate the bone turnover rate i.e., enhanced uptake and release of calcium, so that there were not no net changes in bone total Ca content at the end of the experimental period.
此前有人提出，胃泌素的降钙作用是由一种胃肽胃钙素介导的，该胃肽可增强骨骼对钙（Ca）的摄取。因此，本研究旨在重新确认胃泌素对肌肉和骨骼钙摄取的影响，并评估胃泌素对组织钙摄取的可能直接作用。首先，我们发现，人及大鼠胃泌素（100微克/100克体重（bw），皮下注射）可使胫骨和股骨对胃内给予的45Ca的摄取急性增加。有趣的是，人胃泌素更有效，还可增强腓肠肌对45Ca的摄取。为了确定胃泌素是否能直接作用于骨骼，将10微克大鼠胃泌素/100克bw与45Ca注入供应右腿的右股动脉，而左腿接受生理盐水和等量的45Ca。30分钟时，发现右腓肠肌和股骨中的45Ca含量分别比左腿多168%和162%。相比之下，每天皮下注射25微克大鼠胃泌素/100克bw，持续2周，对肌肉或骨骼的总钙含量没有影响，而在胃泌素处理的大鼠的胫骨和股骨中，第12天和第13天给予的45Ca的含量较低。可以得出结论，胃泌素可短暂增强肌肉和骨骼对钙的摄取。然而，用胃泌素进行两周的治疗似乎会加速骨转换率，即增强钙的摄取和释放，因此在实验期结束时，骨骼总钙含量没有净变化。
