Barakat Hisham, Hickner Robert C, Privette Jonathan, Bower Joseph, Hao Enhui, Udupi Vidya, Green Allan, Pories Walter, MacDonald Ken
Department of Biochemistry, East Carolina University, Greenville, NC 27858, USA.
Metabolism. 2002 Nov;51(11):1514-8. doi: 10.1053/meta.2002.35589.
The purpose of this study was to determine the potential causes of the lower lipolytic rates in obese Black American women compared to obese Caucasian women. Subcutaneous and omental adipose tissue were obtained from subjects during abdominal surgery, and hormone-sensitive lipase (HSL) mass, mRNA, and activity were determined. HSL mRNA levels did not differ between the Black American and Caucasian women in either subcutaneous or omental adipose tissue. However, HSL mass was approximately 35% lower (P <.05) in both subcutaneous and omental adipose tissue of the Black Americans. Because of these differences, we measured HSL activity in frozen subcutaneous and omental adipose tissue, and also measured basal and isoproterenol-stimulated lipolytic rates in tissue fragments. No racial differences were found in the activity of HSL in either subcutaneous or omental adipose tissue. However, basal lipolytic rates in the Black Americans were 53% and 44% lower (P <.05) in the subcutaneous and omental fat, respectively, compared to the Caucasian women, despite a lack of difference in cell size between the 2 groups. Interestingly, the degree of stimulation by isoproterenol was higher in both the subcutaneous and omental adipose tissue of the Black American than those of the Caucasian women, resulting in equal stimulation by isoproterenol in the 2 groups. These results indicate that despite the lower mass and lower basal HSL activity in the obese Black American women, stimulation of HSL results in equal activity of the enzyme in the 2 races. This suggests that the signaling pathway of HSL stimulation is more efficient in the Black American women.
本研究的目的是确定与肥胖的白人女性相比，肥胖的美国黑人女性脂肪分解率较低的潜在原因。在腹部手术期间从受试者获取皮下和网膜脂肪组织，并测定激素敏感性脂肪酶（HSL）的含量、mRNA水平及活性。美国黑人女性和白人女性的皮下或网膜脂肪组织中HSL的mRNA水平没有差异。然而，美国黑人女性皮下和网膜脂肪组织中的HSL含量均低约35%（P<.05）。由于存在这些差异，我们测定了冷冻的皮下和网膜脂肪组织中HSL的活性，还测定了组织碎片中的基础脂肪分解率和异丙肾上腺素刺激的脂肪分解率。皮下或网膜脂肪组织中HSL的活性未发现种族差异。然而，尽管两组细胞大小没有差异，但与白人女性相比，美国黑人女性皮下和网膜脂肪中的基础脂肪分解率分别低53%和44%（P<.05）。有趣的是，美国黑人女性皮下和网膜脂肪组织中异丙肾上腺素的刺激程度均高于白人女性，导致两组中异丙肾上腺素的刺激效果相同。这些结果表明，尽管肥胖的美国黑人女性中HSL含量较低且基础活性较低，但HSL的刺激导致两个种族中该酶的活性相同。这表明美国黑人女性中HSL刺激的信号通路更有效。
