Paulin A, Deshaies Y
Department of Physiology, School of Medicine, Laval University, Québec, Canada.
Physiol Behav. 1991 Oct;50(4):681-7. doi: 10.1016/0031-9384(91)90003-7.
The current study investigated the early response of some determinants of triacylglycerol (TG) metabolism to acute exercise in rats that were treated or not with the nonselective beta-adrenergic blocker, nadolol (25 mg.kg b.wt.-1.day-1 for 30 days). Measurements of hepatic TG secretion rate (HTGSR), postheparin plasma hepatic TG lipase (HTGL) activity, and that of lipoprotein lipase (LPL) in postheparin plasma, heart, vastus lateralis muscle (VLM), white (WAT) and brown (BAT) adipose tissues were carried out in untrained rats at rest or immediately after a 1 h run on treadmill (22 m.min-1, 0 degrees grade). All animals were in the fasted state. Exercise reduced serum TG levels (46% below resting levels) and doubled those of nonesterified fatty acids. HTGSR was enhanced (+28%) by exercise while HTGL activity was not modified. The decrease in postheparin plasma LPL activity (-24%) caused by exercise was consistent with a reduction in enzyme activity in WAT (-32%), BAT (-45%) and heart (-25%). One h of treadmill running did not influence LPL activity in VLM. beta-Adrenergic blockade did not affect any of the variables of lipid metabolism, except for a slight decrease in specific activity of LPL in the heart (-14%). This study demonstrates that absolute variations in HTGSR and in LPL activity cannot account for the acute fall in serum TG levels caused by moderate exercise, in fasted, untrained rats. In addition, these results show that the beta-adrenergic pathway is either not involved in, or not necessary for, the latter effects of exercise on TG metabolism.
本研究调查了三酰甘油（TG）代谢的一些决定因素对急性运动的早期反应，实验对象为用或不用非选择性β-肾上腺素能阻滞剂纳多洛尔（25mg·kg体重-1·天-1，持续30天）处理的大鼠。在未训练的大鼠处于静息状态时，以及在跑步机上跑步1小时（22米·分钟-1，坡度0度）后立即测定肝脏TG分泌率（HTGSR）、肝素后血浆肝脏TG脂肪酶（HTGL）活性以及肝素后血浆、心脏、股外侧肌（VLM）、白色（WAT）和棕色（BAT）脂肪组织中的脂蛋白脂肪酶（LPL）活性。所有动物均处于禁食状态。运动降低了血清TG水平（比静息水平低46%），使非酯化脂肪酸水平翻倍。运动增强了HTGSR（增加28%），而HTGL活性未改变。运动导致的肝素后血浆LPL活性降低（-24%）与WAT（-32%）、BAT（-45%）和心脏（-25%）中酶活性的降低一致。跑步机跑步1小时对VLM中的LPL活性没有影响。β-肾上腺素能阻断除了使心脏中LPL的比活性略有降低（-14%）外，对脂质代谢的任何变量均无影响。本研究表明，在禁食、未训练的大鼠中，HTGSR和LPL活性的绝对变化不能解释适度运动导致的血清TG水平的急性下降。此外，这些结果表明，β-肾上腺素能途径要么不参与运动对TG代谢的后一种作用，要么对其不是必需的。
