Mild hyperbaric oxygen exposure attenuates rarefaction of capillary vessels in streptozotocin-induced diabetic soleus muscle in rats

Abstract

We examined the effects of mild hyperbaric oxygen (mHBO) exposure on capillary rarefaction in skeletal muscles of rats with diabetes. Streptozotocin (100 mg/kg) was administered to male Wis- tar rats via the tail vein to prepare a diabetic model. These rats were divided into 2 groups: the group with mHBO exposure (1.25 atmospheres absolute (ATA) with 36% oxygen; 3 h/day) and the group without mHBO exposure. Age-matched rats were used as the control group. Eight weeks later, the soleus of the rats was removed and then analyzed. With the onset of diabetes mel- litus, capillary number, diameter, and volume in the soleus of the rats with diabetes decreased compared with those of the rats in the control group. In addition, increased anti-angiogenic throm- bospondin-1 (TSP-1) and decreased pro-angiogenic murine double minute 2 (MDM-2) protein ex- pressions were observed in the rats with diabetes. Alternatively, mHBO exposure attenuated the decrease in capillary diameter and volume in skeletal muscles of rats with diabetes, suppressed the overexpression of TSP-1, and restored the MDM-2 expression. These results indicate the exposure of mHBO partially attenuates capillary rarefaction in diabetic soleus muscle.