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首页> 外文期刊>American Journal of Physiology >Relative contributions of Na+/H+ exchange and Na+/HCO3- cotransport to ischemic Nai+ overload in isolated rat hearts.
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Relative contributions of Na+/H+ exchange and Na+/HCO3- cotransport to ischemic Nai+ overload in isolated rat hearts.

机译：Na + / H +交换和Na + / HCO3-共转运对离体大鼠心脏缺血性Nai +超负荷的相对贡献。

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摘要

The Na(+)/H(+) exchanger (NHE) and/or the Na(+)/HCO(3)(-) cotransporter (NBC) were blocked during ischemia in isolated rat hearts. Intracellular Na(+) concentration ([Na(+)](i)), intracellular pH (pH(i)), and energy-related phosphates were measured by using simultaneous (23)Na and (31)P NMR spectroscopy. Hearts were subjected to 30 min of global ischemia and 30 min of reperfusion. Cariporide (3 microM) or HCO(3)(-)-free HEPES buffer was used, respectively, to block NHE, NBC, or both. End-ischemic [Na(+)](i) was 320 +/- 18% of baseline in HCO(3)(-)-perfused, untreated hearts, 184 +/- 6% of baseline when NHE was blocked, 253 +/- 19% of baseline when NBC was blocked, and 154 +/- 6% of baseline when both NHE and NBC were blocked. End-ischemic pH(i) was 6.09 +/- 0.06 in HCO(3)(-)-perfused, untreated hearts, 5.85 +/- 0.02 when NHE was blocked, 5.81 +/- 0.05 when NBC was blocked, and 5.70 +/- 0.01 when both NHE and NBC were blocked. NHE blockade was cardioprotective, but NBC blockade and combined blockade were not, the latter likely due to a reduction in coronary flow, because omission of HCO(3)(-) under conditions of NHE blockade severely impaired coronary flow. Combined blockade of NHE and NBC conserved intracellular H(+) load during reperfusion and led to massive Na(+) influx when blockades were lifted. Without blockade, both NHE and NBC mediate acid-equivalent efflux in exchange for Na(+) influx during ischemia, NHE much more than NBC. Blockade of either one does not affect the other.
机译：Na（+）/ H（+）交换子（NHE）和/或Na（+）/ HCO（3）（-）协同转运子（NBC）在局部大鼠心脏缺血过程中被阻断。通过同时使用（23）Na和（31）P NMR光谱测量细胞内Na（+）浓度（[Na（+）]（i）），细胞内pH（pH（i））和能量相关的磷酸盐。心脏经历了30分钟的整体缺血和30分钟的再灌注。分别使用无Cariporide（3 microM）或不含HCO（3）（-）的HEPES缓冲液来封闭NHE，NBC或两者。缺血终末[Na（+）]（i）在未治疗的HCO（3）（-）灌注心脏中为基线的320 +/- 18％，在NHE阻滞时为基线的184 +/- 6％，253 +当NBC被阻断时，基线为基线的19％，而当NHE和NBC均被阻断时，基线为基线的154 +/- 6％。在未经HCO（3）（-）灌注的未经治疗的心脏中，最终缺血性pH（i）为6.09 +/- 0.06，当NHE被阻断时为5.85 +/- 0.02，当NBC被阻断时为5.81 +/- 0.05，和5.70 + /-当NHE和NBC均被阻断时为0.01。 NHE阻滞具有心脏保护作用，但NBC阻滞和联合阻滞没有作用，后者可能是由于冠状动脉血流减少所致，因为在NHE阻滞条件下省略HCO（3）（-）会严重损害冠脉血流。 NHE和NBC的联合封锁在再灌注期间可保持细胞内H（+）负荷，并在解除封锁时导致大量Na（+）涌入。没有阻滞，NHE和NBC都介导酸当量流出，以换取缺血期间的Na（+）流入，NHE比NBC大得多。任何一方的封锁都不会影响对方。

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