Glitsch H G, Tappe A
Department of Cell Physiology, Ruhr-University Bochum, Federal Republic of Germany.
Pflugers Arch. 1993 Jan;422(4):380-5. doi: 10.1007/BF00374294.
The role of glycolysis and oxidative phosphorylation in providing the ATP for the cardiac Na+/K+ pump was studied in cardioballs from sheep Purkinje fibres. As an indicator of the pump activity, the pump current Ip was measured at -20 mV and 30-33 degrees C by means of whole-cell recording. During intracellular perfusion with a pipette solution containing 5 mM ATP and 15 mM glucose Ip reached a maximum within 8 min and declined to 50% of this value within 27 min after gaining access to the cell interior. Perfusion with an ATP- and glucose-free medium barely enhanced the Ip decline. Inhibition of the oxidative phosphorylation by carbonylcyanide m-chlorophenylhydrazone (CCCP, 2 microM or 20 microM) moderately accelerated the effect of the ATP- and glucose-free pipette solution. Addition of 2 mM iodoacetic acid (an inhibitor of glycolysis) to the latter medium further enhanced the Ip decrease with time. Inhibition of the glycolytic ATP synthesis by 2-deoxy-D-glucose (5 mM) caused a dramatic decline of Ip to half of its maximum within 7.3 min. Pyruvate (5 mM) and inorganic phosphate (2 mM) did not affect the fast Ip decline evoked by the ATP- and glucose-free, 2-deoxyglucose-containing medium, whereas 2 microM CCCP still hastened the fast Ip decrease slightly. This effect of complete metabolic inhibition was reversed by switching to an inhibitor-free pipette solution containing 15 mM ATP. It is concluded that the Na+/K+ pump of cardiac Purkinje cells is preferentially fuelled by glycolytic ATP synthesis.
在绵羊浦肯野纤维制成的心肌球中，研究了糖酵解和氧化磷酸化在为心脏钠钾泵提供ATP方面的作用。作为泵活性的指标，通过全细胞记录在-20 mV和30 - 33℃下测量泵电流Ip。在用含有5 mM ATP和15 mM葡萄糖的移液管溶液进行细胞内灌注期间，Ip在8分钟内达到最大值，并在进入细胞内部后27分钟内降至该值的50%。用不含ATP和葡萄糖的培养基灌注几乎不会加速Ip的下降。用羰基氰化物间氯苯腙（CCCP，2 microM或20 microM）抑制氧化磷酸化可适度加速不含ATP和葡萄糖的移液管溶液的作用。在后者培养基中加入2 mM碘乙酸（糖酵解抑制剂）进一步增强了Ip随时间的下降。用2 - 脱氧 - D - 葡萄糖（5 mM）抑制糖酵解ATP合成导致Ip在7.3分钟内急剧下降至其最大值的一半。丙酮酸（5 mM）和无机磷酸盐（2 mM）不影响由不含ATP和葡萄糖、含2 - 脱氧葡萄糖的培养基引起的Ip快速下降，而2 microM CCCP仍会略微加速Ip的快速下降。通过切换到含有15 mM ATP的无抑制剂移液管溶液，完全代谢抑制的这种作用得以逆转。结论是，心脏浦肯野细胞的钠钾泵优先由糖酵解ATP合成提供能量。
