The suppressive and cytotoxic effects of interleukin-1β(IL-β) on rodent insulin-producing cells observed in vitro are probably mediated through formation or nitric oxide (NO). In this study we demonstrate that IL-1-induced NO formation in isolated rat islets and insulin-producing HIT cells is more sensitive to inhibition by N G-monomethyl-l-arginine than to inhibition by N G-nitro-l-arginine, thus suggesting that IL-1-exposed insulin producing cells express an isoform of nitric oxide synthase similar to that present in activated macrophages, Furthermore, IL-1β markedly increased the mRNA levels or the inducible microphage form of nitric oxide synthase in HIT cells.
