Abstract
Glucose metabolism via sorbitol pathway has been implicated as a possible contributor to the diabetes-related vascular changes. Nitric oxide plays a major regulatory role in the vascular dilatatory and constricted response. Also it has been observed that diabetes causes vascular changes leading to a decrease in nitric oxide production. Additionally the accumulation of sorbitol is also related to decreased nitric oxide production. In the present study we investigated the effect of normal and high glucose in the presence or absence of both interleukin-1β or an aldose reductase inhibitor on nitric oxide production in rat aortic rings in vitro. Aortic rings from normal male Wistar rats were dissected and incubated for 24 to 48 hrs in the presence of glucose (5.0 mM or 20 mM) or with or without interleukin (20 ng/ml). Other rings were incubated in the above media with the addition of the aldose reductase inhibitor (WAY 121509). Interleukin-1β stimulated the 24 hr nitric oxide production and WAY 121509 decreased it under both low and high glucose culture conditions. The interleukin-1β stimulation was continued for 72 hrs. Nitric oxide production in response to interleukin-1β was greater at all time points when compared to the incubation in media without interleukin-1β. In media containing WAY 121509 the nitric oxide production was decreased. Interleukin-1β stimulated a greater increase in nitric oxide production from aortic rings when incubated in high glucose when compared to normal glucose. The inhibitory effect of aldose reductase inhibition was reversible after 24 hr inhibition under both normal and high glucose conditions. We conclude that high glucose enhances the interleukin- 1β-induced nitric oxide synthesis and the cytokine-induced nitric oxide production was inhibited by aldose reductase inhibition. Nitric oxide production may be linked to redox influences caused by the polyol pathway.
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