摘要
Lactate is an anaerobic metabolite produced in the absence of an adequate O2 supply. Although for a long time considered to be a waste product of glycolysis resulting from hypoxia, lactate is, in fact, an important source of glucose and also a gluconeogenic precursor, having a role in metabolic and endocrine signaling. Lactate is produced by adipocytes and muscle cells. Objectives: In this study, we investigated the sex differences in lactate production by adipocytes isolated from lean human visceral adipose tissue. Main Methods: The experiments described were done using adipocytes isolated from adipose tissue of lean men and women. Adipocytes were isolated following Rodbell procedure, with modifications, for posterior analysis of glycerol and lactate production. Results: Morphometric analysis revealed no significant differences in the size of adipocytes from men and women (diameter: men: 172 ± 24 μm vs. women: 160 ± 16 μm, n = 4 and 10, respectively). Basal glycerol production was significantly higher in adipocytes from men compared to women (0.34 ± 0.06 vs. 0.16 ± 0.01 μmol/106 cells/60 min;mean ± SEM, n = 7 and 4, respectively;p < 0.05), but there was no significant difference in basal lactate production (men: 0.1 ± 0.01 μmol/10 cells/60 min vs. women: 0.12 ± 0.02 μmol/10 cells/60 min). However, when stimulated by norepinephrine, adipocytes from women produced more lactate than adipocytes from men. Female adipocytes also produced as much lactate as glycerol, whereas male adipocytes produced three times more glycerol than lactate. The intracellular mechanisms responsible for this sex difference in lactate production during norepinephrine-stimulated lipolysis remain to be identified.
Lactate is an anaerobic metabolite produced in the absence of an adequate O2 supply. Although for a long time considered to be a waste product of glycolysis resulting from hypoxia, lactate is, in fact, an important source of glucose and also a gluconeogenic precursor, having a role in metabolic and endocrine signaling. Lactate is produced by adipocytes and muscle cells. Objectives: In this study, we investigated the sex differences in lactate production by adipocytes isolated from lean human visceral adipose tissue. Main Methods: The experiments described were done using adipocytes isolated from adipose tissue of lean men and women. Adipocytes were isolated following Rodbell procedure, with modifications, for posterior analysis of glycerol and lactate production. Results: Morphometric analysis revealed no significant differences in the size of adipocytes from men and women (diameter: men: 172 ± 24 μm vs. women: 160 ± 16 μm, n = 4 and 10, respectively). Basal glycerol production was significantly higher in adipocytes from men compared to women (0.34 ± 0.06 vs. 0.16 ± 0.01 μmol/106 cells/60 min;mean ± SEM, n = 7 and 4, respectively;p < 0.05), but there was no significant difference in basal lactate production (men: 0.1 ± 0.01 μmol/10 cells/60 min vs. women: 0.12 ± 0.02 μmol/10 cells/60 min). However, when stimulated by norepinephrine, adipocytes from women produced more lactate than adipocytes from men. Female adipocytes also produced as much lactate as glycerol, whereas male adipocytes produced three times more glycerol than lactate. The intracellular mechanisms responsible for this sex difference in lactate production during norepinephrine-stimulated lipolysis remain to be identified.
基金
This study was supported by grants from the National Council for Scientific and Technological Development(CNPq) and the Sao Paulo Research Foundation (FAPESP). We thank Espaço da Escrita Coordenadoria Geral da Universidade UNICAMP for the text revision.
