Department of Pediatrics, Division of Neonatology and Developmental Biology, Neonatal Research Center, David Geffen School of Medicine, University of California at Los Angeles, 10833 Le Conte Ave., Los Angeles, CA 90095, USA.
Am J Physiol Endocrinol Metab. 2012 Jun 1;302(11):E1352-62. doi: 10.1152/ajpendo.00539.2011. Epub 2012 Feb 14.
Associations between exponential childhood growth superimposed on low birth weight and adult onset cardiovascular disease with glucose intolerance/type 2 diabetes mellitus exist in epidemiological investigations. To determine the metabolic adaptations that guard against myocardial failure on subsequent exposure to hypoxia, we compared with controls (CON), the effect of intrauterine (IUGR), postnatal (PNGR), and intrauterine and postnatal (IPGR) calorie and growth restriction (n = 6/group) on myocardial macronutrient transporter (fatty acid and glucose) -mediated uptake in pregestational young female adult rat offspring. A higher myocardial FAT/CD36 protein expression in IUGR, PNGR, and IPGR, with higher FATP1 in IUGR, FATP6 in PNGR, FABP-c in PNGR and IPGR, and no change in GLUT4 of all groups was observed. These adaptive macronutrient transporter protein changes were associated with no change in myocardial [(3)H]bromopalmitate accumulation but a diminution in 2-deoxy-[(14)C]glucose uptake. Examination of the sarcolemmal subfraction revealed higher basal concentrations of FAT/CD36 in PNGR and FATP1 and GLUT4 in IUGR, PNGR, and IPGR vs. CON. Exogenous insulin uniformly further enhanced sarcolemmal association of these macronutrient transporter proteins above that of basal, with the exception of insulin resistance of FATP1 and GLUT4 in IUGR and FAT/CD36 in PNGR. The basal sarcolemmal macronutrient transporter adaptations proved protective against subsequent chronic hypoxic exposure (7 days) only in IUGR and PNGR, with notable deterioration in IPGR and CON of the echocardiographic ejection fraction. We conclude that the IUGR and PNGR pregestational adult female offspring displayed a resistance to insulin-induced translocation of FATP1, GLUT4, or FAT/CD36 to the myocardial sarcolemma due to preexistent higher basal concentrations. This basal adaptation of myocardial macronutrient transporters ensured adequate fatty acid uptake, thereby proving protective against chronic hypoxia-induced myocardial compromise.
在流行病学研究中,低出生体重与成年后心血管疾病和葡萄糖耐量/2 型糖尿病之间存在指数型儿童生长叠加的关联。为了确定代谢适应机制可以防止心肌在随后暴露于缺氧时衰竭,我们将宫内(IUGR)、产后(PNGR)和宫内及产后(IPGR)卡路里和生长受限(每组 6 只)对妊娠前年轻雌性成年大鼠后代心肌大分子营养转运体(脂肪酸和葡萄糖)介导的摄取的影响与对照组(CON)进行了比较。在 IUGR、PNGR 和 IPGR 中观察到心肌 FAT/CD36 蛋白表达升高,IUGR 中 FATP1 升高,PNGR 中 FATP6 升高,PNGR 和 IPGR 中 FABP-c 升高,而所有组的 GLUT4 均无变化。这些适应性的大分子营养转运体蛋白变化与心肌 [(3)H]溴棕榈酸积累无变化有关,但 2-脱氧-[(14)C]葡萄糖摄取减少。对肌膜亚部分的检查显示,PNGR 中的 FAT/CD36 和 IUGR 中的 FATP1 和 GLUT4 的基础浓度较高。与 CON 相比,外源性胰岛素均匀地进一步增强了这些大分子营养转运体蛋白在基础水平之上的肌膜结合,除了 IUGR 中的 FATP1 和 GLUT4 以及 PNGR 中的 FAT/CD36 存在胰岛素抵抗之外。基础肌膜大分子营养转运体的适应性仅在 IUGR 和 PNGR 中对随后的慢性缺氧暴露(7 天)具有保护作用,而在 IPGR 和 CON 中则明显恶化,表现为超声心动图射血分数的恶化。我们得出结论,IUGR 和 PNGR 妊娠前成年雌性后代由于预先存在的较高基础浓度而表现出对胰岛素诱导的 FATP1、GLUT4 或 FAT/CD36 向心肌肌膜易位的抵抗。心肌大分子营养转运体的这种基础适应性确保了足够的脂肪酸摄取,从而对慢性缺氧诱导的心肌损伤具有保护作用。