Gitomer W L, Franco-Cabrera B D, Storey C J
Department of Radiology, UT Southwestern Medical Center, Dallas 75235-9071.
Biochem Int. 1992 Mar;26(4):637-44.
Rabbit hearts were perfused with Krebs-Henseleit bicarbonate buffer supplemented with 15 mM glucose and 10 mU/ml of insulin +/- Pi. At the end of 60 min the hearts were freeze-clamped and the content of ATP, creatine phosphate, creatine, lactate, pyruvate, DHAP and 3-P glycerate were determined enzymatically in neutralized perchloric acid tissue extracts. The free cytosolic ADP and Pi and the cytosolic NAD+ redox and phosphorylation potentials were calculated from the measured metabolite concentrations. Pi free perfusion resulted in increased creatine, free cytosolic ADP and cytosolic phosphorylation potential, decreased calculated free Pi and no change in cardiac ATP and creatine phosphate content. The increase in the cytosolic phosphorylation potential was due to the lowering of cytosolic free Pi. The increase in ADP was due to the increase in creatine. The increase in creatine appeared to be due to an inhibition of creatine efflux from the heart during Pi free perfusion which was mediated by an enhanced Na+ electrochemical gradient.
用补充了15 mM葡萄糖和10 mU/ml胰岛素（±无机磷酸盐）的克氏-亨氏碳酸氢盐缓冲液灌注兔心脏。60分钟结束时，将心脏速冻钳夹，并在中和的高氯酸组织提取物中通过酶法测定三磷酸腺苷（ATP）、磷酸肌酸、肌酸、乳酸、丙酮酸、磷酸二羟丙酮（DHAP）和3-磷酸甘油酸的含量。根据测得的代谢物浓度计算游离胞质二磷酸腺苷（ADP）和无机磷酸盐以及胞质烟酰胺腺嘌呤二核苷酸（NAD⁺）氧化还原和磷酸化电位。无无机磷酸盐灌注导致肌酸增加、游离胞质ADP增加和胞质磷酸化电位增加，计算出的游离无机磷酸盐减少，心脏ATP和磷酸肌酸含量无变化。胞质磷酸化电位的增加是由于胞质游离无机磷酸盐降低所致。ADP的增加是由于肌酸增加所致。肌酸的增加似乎是由于在无无机磷酸盐灌注期间心脏肌酸流出受到抑制，这是由增强的钠离子电化学梯度介导的。
