Barron J T, Bárány M, Gu L, Parrillo J E
Department of Medicine, Rush Medical College, Rush-Presbyterian-St. Luke's Medical Center, Chicago, Illinois 60612, USA.
Biochim Biophys Acta. 1997 Dec 15;1322(2-3):208-20. doi: 10.1016/s0005-2728(97)00076-5.
The oxidation of octanoate and acetate was measured in segments of porcine carotid arteries to ascertain whether the oxidation of exogenous fatty acid substrates (acetate and octanoate) is augmented during contraction induced by K(+)-depolarization. The oxidation of acetate increased from 7 +/- 1 to 14 +/- 2 nmol/min/g (P < 0.01) during sustained isometric contraction. Octanoate oxidation increased from 11 +/- 1 to 14 +/- 1 nmol/min/g (P < 0.05). The rate of oxidation of neither acetate nor octanoate was affected by the presence or absence of glucose either in resting or contracting arteries Acetate or octanoate oxidation could account for the majority of O2 consumption during contraction. Octanoate but not acetate inhibited glucose uptake and glycolysis in resting muscles. In contrast to augmented acetate and octanoate metabolism during contraction, there was a "down-regulation" of glucose metabolism in contracting muscles as evidenced by a decrease in the rate of glucose uptake, glycolysis and lactic acid production during sustained isometric contraction. Thus, contractile activation of vascular smooth muscle is associated with a shifting pattern of substrate utilization. Exogenous acetate or octanoate can serve as the primary oxidative substrate during sustained isometric contraction.
在猪颈动脉段中测量辛酸酯和乙酸酯的氧化，以确定在钾离子去极化诱导的收缩过程中，外源性脂肪酸底物（乙酸酯和辛酸酯）的氧化是否增强。在持续等长收缩期间，乙酸酯的氧化从7±1增加到14±2 nmol/分钟/克（P<0.01）。辛酸酯氧化从11±1增加到14±1 nmol/分钟/克（P<0.05）。在静息或收缩的动脉中，无论有无葡萄糖，乙酸酯和辛酸酯的氧化速率均不受影响。乙酸酯或辛酸酯氧化可占收缩期间大部分氧气消耗。辛酸酯而非乙酸酯在静息肌肉中抑制葡萄糖摄取和糖酵解。与收缩期间乙酸酯和辛酸酯代谢增强相反，收缩肌肉中的葡萄糖代谢出现“下调”，这在持续等长收缩期间葡萄糖摄取、糖酵解和乳酸产生速率降低中得到证明。因此，血管平滑肌的收缩激活与底物利用模式的转变有关。在持续等长收缩期间，外源性乙酸酯或辛酸酯可作为主要的氧化底物。
