Martens H, Gäbel G, Strozyk H
Q J Exp Physiol. 1987 Apr;72(2):181-8. doi: 10.1113/expphysiol.1987.sp003062.
Isolated mucosal sheets of sheep rumen were studied in vitro in Ussing chambers using a computer-controlled voltage clamp. Undirectional Mg2+ fluxes were measured at high (70 mmol X l-1) or low (5 mmol X l-1) mucosal concentrations of K+ under open- or voltage-clamp conditions. A high mucosal concentration of K+ caused a potential difference (p.d.) of 25.1 +/- 1.8 mV, blood side positive. The Mg2+ fluxes were 52.2 +/- 6.5 nmol X cm-2 X h-1 from the mucosal to serosal side, JMgms, and 11.6 +/- 1.4 nmol X cm-2 X h-1 from the serosal to mucosal side, JMgsm. The net flux, JMgnet, was 40.6 +/- 5.9 nmol X cm-2 X h-1. When, at high mucosal K+ concentrations the p.d. was abolished by an external current (short-circuit conditions) significantly different flux data were obtained: JMgms, 76.1 +/- 8.3; JMgsm, 8.0 +/- 1.4; and JMgnet 68.1 +/- 7.7 nmol X cm-2 X h-1. The results of the low (control) and high mucosal K+ group did not differ significantly when Mg2+ fluxes were measured under short-circuit conditions: JMgms, 72.1 +/- 8.7; JMgsm, 6.5 +/- 2.6; and JMgnet, 65.5 +/- 9.0 nmol X cm-2 X h-1. An increase of the p.d. to 26.6 +/- 2.0 mV (control) by an external current led to significant alterations of the fluxes in the control group: JMgms, 47.4 +/- 3.0; JMgsm, 12.3 +/- 2.3; and JMgnet, 35.2 +/- 4.1 nmol X cm-2 X h-1.(ABSTRACT TRUNCATED AT 250 WORDS)
在体外使用计算机控制的电压钳在尤斯灌流小室中对绵羊瘤胃的孤立黏膜片进行了研究。在开放或电压钳条件下，于高（70 mmol·L⁻¹）或低（5 mmol·L⁻¹）黏膜钾浓度下测量单向镁离子通量。高黏膜钾浓度导致电位差（p.d.）为25.1±1.8 mV，血液侧为正。镁离子通量从黏膜到浆膜侧为52.2±6.5 nmol·cm⁻²·h⁻¹（JMgms），从浆膜到黏膜侧为11.6±1.4 nmol·cm⁻²·h⁻¹（JMgsm）。净通量（JMgnet）为40.6±5.9 nmol·cm⁻²·h⁻¹。当在高黏膜钾浓度下通过外部电流消除电位差（短路条件）时，获得了显著不同的通量数据：JMgms为76.1±8.3；JMgsm为8.0±1.4；JMgnet为68.1±7.7 nmol·cm⁻²·h⁻¹。在短路条件下测量镁离子通量时，低（对照）和高黏膜钾组的结果无显著差异：JMgms为72.1±8.7；JMgsm为6.5±2.6；JMgnet为65.5±9.0 nmol·cm⁻²·h⁻¹。通过外部电流将电位差增加到26.6±2.0 mV（对照）导致对照组通量发生显著变化：JMgms为47.4±3.0；JMgsm为12.3±2.3；JMgnet为35.2±4.1 nmol·cm⁻²·h⁻¹。（摘要截短于250字）
