Increasing of oxidative stress from mitochondria in type 2 diabetic patients

Recent evidence increasingly indicates that oxidative stress may play an important role in the pathogenesis of diabetic vascular complications. Mitochondria has received much attention as an important organ in the generation of oxidative stress. However, the importance of oxidative stress among diabetic patients without vascular complications is unclear.

We compared oxidative stress produced from mitochondria of the mononuclear cells in peripheral blood obtained from 26 diabetic subjects without clinical vascular complications and 52 healthy age-matched subjects using a flow cytometer. Oxidative stress from the mononuclear cells was evaluated by measuring fluorescence of oxidized production from dihydrorhodamine-123, which is a pro-fluorescent compound that selectively accumulates in the mitochondria of living cells. Stimulation of the cells was carried out with phorbol 12-myristate 13-acetate (PMA), a protein kinase C (PKC) activator. We then calculated the relative fluorescence variation (RFV) that indicated an increasing rate of oxidative stress levels by stimulation with PMA against the levels obtained at baseline. Additionally, we measured the urinary stress markers, 8-hydroxydeoxyguanosine (8OHdG) and 8-epi-prostaglandin F2alpha (isoprostane).

Compared to healthy subjects, diabetic subjects did not exhibit significantly elevated oxidative stress levels at baseline, but did have significantly elevated basal urinary 8OHdG, urinary isoprostane and oxidative stress levels after PMA stimulation as well as RFV.

Among diabetic subjects without clinical vascular complications, there was a possibility that mitochondrial oxidative stress balance between generation and scavenging against the additive PKC stimulation was thought to have already been lost.