Abstract
It is known that dysfunction of sciatic nerves in diabetes is related to disturbance of blood microcirculation in the axon and sheath of peripheral nerves. Oxygen free radicals also affect vascular reactivity and produce dysfunction of blood microcirculation in organs. There is, however, little information that high oxygen tension regulates mechanical activity of arterioles in sciatic nerves. The present study thus investigated effects of high oxygen tension on the activity of arterioles in rat sciatic nerves by an intra-vital videomicroscope system. Seven-week-old male Wistar rats were anesthetized by subcutaneous injection of 2% α-chloralose and 10% urethane. The left femoral artery was cannulated to measure arterial blood pressure. The arterioles of right sciatic nerves were observed by using of the intra-vital videomicroscope. Krebs-bicarbonate solution (KBS) was superfused onto the sciatic nerve and changes in the diameter of the arterioles were investigated in response to normal (PO2; ∼5 mmHg) or high oxygenated (PO2; ∼140 mmHg) KBS. The superfusion of normal KBS onto the sciatic nerves did not affect diameter of the arterioles, while the superfusion of high oxygenated KBS significantly and time-dependently constricted the arterioles for 10 min (from 18.0 ± 2.0 μm to 9.7 ± 2.0 μm). These results suggest that high oxygen tension constricts rat sciatic nervous arterioles and affect microcirculation of the peripheral nervous system in vivo. [Jpn J Physiol 55 Suppl:S94 (2005)]
