Barron J T, Kopp S J, Tow J, Parrillo J E
Department of Medicine, Rush Medical College, Chicago 60612, USA.
Am J Physiol. 1996 Jun;270(6 Pt 2):H1869-77. doi: 10.1152/ajpheart.1996.270.6.H1869.
Energy metabolism and the substrate utilization pattern of intact porcine carotid artery were investigated in the presence or absence of glucose and/or octanoate during the phases of isometric contraction induced by K+ depolarization. During the early phase of contraction, there was a rapid increase in the rate of O2 uptake that was independent of the rate of force generation but dependent on the availability of intracellular pyruvate, the source of which was glucose and not glycogen. Lactate production increased linearly from the onset of contractile stimulation and was not suppressed by octanoate oxidation. There was no alteration from the basal resting state in the concentrations of the metabolites of the tricarboxylic acid cycle in the presence or absence of octanoate. During the phase of steady-state force maintenance, O2 consumption was increased compared with the basal unstimulated rate but was not increased when glucose and octanoate were present, which is consistent with the Crabtree effect. This was associated with increased aerobic lactic acid production and inhibition of the tricarboxylic acid cycle at the citrate synthase step. Alteration of the high-energy phosphate content could not account for the pattern of O2 consumption during contraction under different substrate conditions. In the absence of glucose, the energy from octanoate oxidation could substitute for the energy ordinarily derived from aerobic glycogen and lactic acid production. It is concluded that energy metabolism of vascular smooth muscle is coordinated during contraction by integration of the pathways of aerobic glycolysis and oxidative phosphorylation.
在钾离子去极化诱导的等长收缩阶段，研究了完整猪颈动脉在有或无葡萄糖和/或辛酸存在时的能量代谢及底物利用模式。在收缩早期，氧气摄取速率迅速增加，这与力产生速率无关，但依赖于细胞内丙酮酸的可用性，其来源是葡萄糖而非糖原。乳酸产生从收缩刺激开始时呈线性增加，且不受辛酸氧化的抑制。无论有无辛酸，三羧酸循环代谢物浓度与基础静息状态相比均无变化。在稳态力维持阶段，与基础未刺激速率相比，氧气消耗增加，但当存在葡萄糖和辛酸时并未增加，这与克奈特效应一致。这与有氧乳酸产生增加及三羧酸循环在柠檬酸合酶步骤受到抑制有关。高能磷酸含量的改变无法解释不同底物条件下收缩期间的氧气消耗模式。在无葡萄糖时，辛酸氧化产生的能量可替代通常由有氧糖原和乳酸产生的能量。结论是，血管平滑肌的能量代谢在收缩过程中通过有氧糖酵解和氧化磷酸化途径的整合而协调。
