Chloride, gluconate, sulfate, and short-chain fatty acids affect calcium flux rates across the sheep forestomach epithelium.
Chloride, gluconate, sulfate, and short-chain fatty acids affect calcium flux rates across the sheep forestomach epithelium.
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DOI：
10.3168/jds.s0022-0302(07)71637-5
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发表时间：
2007-03
影响因子：
3.5
通讯作者：
S. Leonhard-Marek;G. Becker;G. Breves;B. Schröder
中科院分区：
文献类型：
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作者：
S. Leonhard-Marek;G. Becker;G. Breves;B. Schröder
在反刍动物中，超过50%的胃肠道钙吸收可以发生在肠前，口服钙盐的阴离子被认为在促进瘤胃钙吸收中起着重要作用。这一假设主要是基于使用葡萄糖酸盐作为控制阴离子的离子交换研究，这可能会结合钙离子并干扰治疗效果。在本研究中，我们研究了不同阴离子对绵羊瘤胃钙吸收和游离钙离子浓度的不同影响。我们发现葡萄糖酸盐、硫酸盐和短链脂肪酸(SCFA)显著降低了缓冲溶液中的[Ca~(2+)]离子。然而，增加60 mM的Cl或SCFA浓度可促进瘤胃钙净吸收5~7倍，但这些作用可被葡萄糖酸盐拮抗。因此，离子交换实验必须非常仔细地评估，因为在葡萄糖酸盐、硫酸盐或SCFA存在的情况下，[Ca2+]离子的变化不仅可能导致对钙通量速率的低估，还可能对其他依赖于钙离子的细胞途径产生影响。关于奶牛的最佳钙供应，本研究表明，CaCl2配方和SCFA的钙盐可促进跨瘤胃壁的钙吸收，有利于预防或纠正钙缺乏症。
In ruminants, more than 50% of overall gastrointestinal Ca absorption can occur preintestinally, and the anions of orally applied Ca salts are thought to play an important role in stimulating ruminal Ca absorption. This assumption is based mainly on ion-exchange studies that have used gluconate as the control anion, which may bind Ca2+ ions and interfere with treatment effects. In the present study, we investigated the distinct effects of different anions on Ca absorption across the sheep rumen and on the concentration of free Ca2+ ions ([Ca2+]ion). We showed that gluconate, sulfate, and short-chain fatty acids (SCFA) remarkably reduced [Ca2+]ion in buffer solutions. Nevertheless, increasing the Cl or SCFA concentration by 60 mM stimulated net ruminal Ca absorption 5- to 7-fold, but these effects could be antagonized by gluconate. Therefore, ion-exchange experiments must be (re)evaluated very carefully, because changes in [Ca2+]ion in the presence of gluconate, sulfate, or SCFA not only might entail an underestimation of Ca flux rates, but also might have effects on other cellular pathways that are Ca2+ dependent. Concerning the optimal Ca supply for dairy cows, the present study suggests that CaCl2 formulations and Ca salts of the SCFA stimulate Ca absorption across the rumen wall and are beneficial in preventing or correcting a Ca deficiency.