• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>American Journal of Physiology >Basolateral Mg2+/Na+ exchange regulates apical nonselective cation channel in sheep rumen epithelium via cytosolic Mg2+.
【24h】

Basolateral Mg2+/Na+ exchange regulates apical nonselective cation channel in sheep rumen epithelium via cytosolic Mg2+.

机译：基底外侧的Mg2 + / Na +交换通过细胞质Mg2 +调节绵羊瘤胃上皮细胞的顶端非选择性阳离子通道。

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

High potassium diets lead to an inverse regulation of sodium and magnesium absorption in ruminants, suggesting some form of cross talk. Previous Ussing chamber experiments have demonstrated a divalent sensitive Na(+) conductance in the apical membrane of ruminal epithelium. Using patch-clamped ruminal epithelial cells, we could observe a divalent sensitive, nonselective cation conductance (NSCC) with K(+) permeability > Cs(+) permeability > Na(+) permeability. Conductance increased and rectification decreased when either Mg(2+) or both Ca(2+) and Mg(2+) were removed from the internal or external solution or both. The conductance could be blocked by Ba(2+), but not by tetraethylammonium (TEA). Subsequently, we studied this conductance measured as short-circuit current (I(sc)) in Ussing chambers. Forskolin, IBMX, and theophylline are known to block both I(sc) and Na transport across ruminal epithelium in the presence of divalent cations. When the NSCC was stimulated by removing mucosal calcium, an initial decrease in I(sc) was followed by a subsequent increase. The cAMP-mediated increase in I(sc) was reduced by low serosal Na(+) and serosal addition of imipramine or serosal amiloride and depended on the availability of mucosal magnesium. Luminal amiloride had no effect. Flux studies showed that low serosal Na(+) reduced (28)Mg fluxes from mucosal to serosal. The data suggest that cAMP stimulates basolateral Na(+)/Mg(2+) exchange, reducing cytosolic Mg. This increases sodium uptake through a magnesium-sensitive NSCC in the apical membrane. Likewise, the reduction in magnesium uptake that follows ingestion of high potassium fodder may facilitate sodium absorption, as observed in studies of ruminal osmoregulation. Possibly, grass tetany (hypomagnesemia) is a side effect of this useful mechanism.
机译：高钾饮食导致反刍动物钠和镁吸收的反调节，表明某种形式的串扰。先前的Ussing chamber实验已证明瘤胃上皮的顶膜中有二价敏感的Na（+）电导。使用膜片钳瘤胃上皮细胞，我们可以观察到二价敏感，非选择性阳离子电导（NSCC）与K（+）渗透率> Cs（+）渗透率> Na（+）渗透率。从内部或外部溶液或两者中除去Mg（2+）或Ca（2+）和Mg（2+）两者时，电导增加而整流降低。电导可以被Ba（2+）阻止，但不能被四乙铵（TEA）阻止。随后，我们研究了在电导室中测量为短路电流（I（sc））的电导。已知在存在二价阳离子的情况下，福斯高林，IBMX和茶碱会阻止I（sc）和Na转运穿过瘤胃上皮。当通过去除粘膜钙刺激NSCC时，I（sc）最初下降，随后上升。低浆膜Na（+）和浆膜添加丙咪嗪或浆膜阿米洛利减少了cAMP介导的I（sc）的增加，这取决于粘膜镁的可用性。发光的阿米洛利没有作用。助焊剂研究表明低浆膜Na（+）减少（28）Mg从粘膜到浆膜的通量。数据表明，cAMP刺激基底外侧Na（+）/ Mg（2+）交换，减少胞质Mg。这增加了通过对镁敏感的根尖细胞膜中的钠离子对钠的吸收。同样，如瘤胃渗透压研究中所观察到的那样，摄入高钾饲料后镁摄入减少可能促进钠吸收。草破伤风（低镁血症）可能是这种有用机制的副作用。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号