Nasu T, Shibata A
Department of Veterinary Pharmacology, Faculty of Agriculture, Yamaguchi University, Yamaguchi 753, Japan.
Pharmacol Res. 2000 Dec;42(6):511-5. doi: 10.1006/phrs.2000.0704.
The action of ouabain, an external Na(+)-dependent inhibitor of active glucose transport, on the contraction by Mn(2+)in a Ca(2+)-free, Na(+)-sufficient or Na(+)-deficient medium was examined in ileal muscle. Ouabain ( 9 x 10(-5)m) inhibited the contraction by 5 mm Mn(2+)in a Ca(2+)-free, 60 mm K(+), Na(+)-sufficient medium in ileal muscle. The addition of pyruvate or lactate, utilized independently in the external Na(+)in the pretreatment with ouabain, induced the dose-dependent contraction and manganese uptake by Mn(2+)in the Ca(2+)-free, 60 mm K(+), Na(+)-sufficient medium. These results suggest that Mn(2+)-induced ileal contraction in a high-K(+), Na(+)-sufficient medium is maintained by an active glucose transport, dependent on external Na(+). While, in contrast, Mn(2+)-induced contraction in a high-K(+), Na(+)-deficient medium is maintained by an external Na(+)-independent glucose transport, and is insensitive to ouabain.
哇巴因是一种胞外依赖于钠离子的主动葡萄糖转运抑制剂，本研究在回肠肌肉中检测了哇巴因在无钙、钠离子充足或钠离子缺乏的培养基中对锰离子诱导收缩的作用。在无钙、60mM钾离子、钠离子充足的回肠肌肉培养基中，哇巴因（9×10⁻⁵M）抑制了5mM锰离子诱导的收缩。在用哇巴因预处理时，单独利用胞外钠离子的丙酮酸或乳酸的添加，在无钙、60mM钾离子、钠离子充足的培养基中诱导了剂量依赖性收缩和锰离子摄取。这些结果表明，在高钾、钠离子充足的培养基中，锰离子诱导的回肠收缩由依赖于胞外钠离子的主动葡萄糖转运维持。然而，相比之下，在高钾、钠离子缺乏的培养基中，锰离子诱导的收缩由不依赖于胞外钠离子的葡萄糖转运维持，且对哇巴因不敏感。
