[High glucose impairs mitochondrial respiratory chain function in pancreatic beta cells].
OBJECTIVE
To investigate the effect of high glucose on mitochondrial respiratory chain function in INS-1 cells.


METHODS
The pancreatic beta cell line INS-1 was divided into the normal control (NC), high glucose (HG), and N-acetyl-L-cysteine (NAC) pretreatment groups, which were cultured for 72 h in the presence of 5.5 mmol/L glucose, 16.7 mmol/L glucose, and 16.7 mmol/L glucose with 1.0 mmol/L NAC, respectively. The activities of the enzyme complexes I and III of the respiratory chain in the cells were assessed with spectrophotometry, the ATP levels were examined using a luciferinluciferase kit, and insulin levels detected by radioimmunoassay.


RESULTS
The activities of the respiratory chain enzyme complexes I and III were 1.53-/+0.24 and 1.08-/+0.22 micromol.mg(-1).min(-1) in high glucose group, respectively, significantly lower than those in the normal control group (2.31-/+0.33 and 1.92-/+0.39 micromol.mg(-1).min(-1), P<0.01). ATP and insulin levels also decreased significantly in high glucose group as compared with those in the normal control group (P<0.01). The addition of NAC partially inhibited high glucose-induced decreases in the enzyme complex activities, ATP levels and insulin secretion (P<0.05).


CONCLUSIONS
The respiratory chain function is positively correlated to insulin secretion in INS-1 cells, and exposure to high glucose causes impairment of the two enzyme complexes activities through oxidative stress, resulting in the mitochondrial respiratory chain dysfunction. High glucose-induced damages of the mitochondrial respiratory chain function can be partially inhibited by NAC.
Lin
Zhan
Z
Department of Endocrinology and Metabolism, Nanfang Hospital, Southern Medical University, Guangzhou, China. linzhanok@163.com
Xue
Yao-Ming
YM
Sha
Jian-Ping
JP
Mao
Rui-Rui
RR
Long
Ke
K
Sang
Dan
D
D019069:Cell Respiration / Q000187:drug effects; D002478:Cells, Cultured; D005947:Glucose / Q000494:pharmacology*; D006801:Humans; D050417:Insulin-Secreting Cells / Q000166:cytology* / Q000502:physiology*; D008928:Mitochondria / Q000502:physiology*; D018384:Oxidative Stress / Q000187:drug effects
D005947:Glucose