Sanders M J, Simon L M, Misfeldt D S
J Cell Physiol. 1983 Mar;114(3):263-6. doi: 10.1002/jcp.1041140303.
The renal cell line LLC-PK1 cotransports Na and D-glucose from the apical to the basolateral side of the cell monolayer, and the short-circuit current (Isc) measures the net amount of Na transported. Under conditions of maximal cotransport, the addition of phlorizin or removal of Na reversibly decreased oxygen consumption by one-half. In the absence of glycolytic substrates, alpha-methyl-D-glucoside stimulated Isc and oxygen consumption, although the Isc came to a steady state 50% less than when glycolytic substrates were present. The addition of other aerobic substrates did not increase Isc; however, when non-cotransported glycolytic substrates were introduced the Isc returned to a maximum with an associated fall in oxygen consumption and increased lactate production. Thus, in the absence of glycolytic substrates aerobic ATP formation may be rate-limiting for Na, D-glucose cotransport. For this epithelium glycolysis makes an important contribution to the provision of energy for transport. Oxygen consumption does not correlate well with Isc and is not a good measure of the energy used in transport.
肾细胞系LLC-PK1将Na和D-葡萄糖从细胞单层的顶端共转运至基底外侧，短路电流（Isc）可测量转运的Na的净量。在最大共转运条件下，加入根皮苷或去除Na可使耗氧量可逆性降低一半。在没有糖酵解底物的情况下，α-甲基-D-葡萄糖苷刺激Isc和耗氧量，尽管Isc达到的稳态比存在糖酵解底物时低50%。添加其他需氧底物不会增加Isc；然而，当引入非共转运的糖酵解底物时，Isc恢复到最大值，同时耗氧量下降，乳酸生成增加。因此，在没有糖酵解底物的情况下，有氧ATP的形成可能是Na、D-葡萄糖共转运的限速因素。对于这种上皮细胞，糖酵解对提供转运所需能量起着重要作用。耗氧量与Isc的相关性不佳，不是转运中能量消耗的良好指标。
