Rapid stimulation of L-arginine transport by D-glucose involves p42/44mapk and nitric oxide in human umbilical vein endothelium

Abstract

D-Glucose infusion and gestational diabetes induce vasodilatation in humans and increase L-arginine transport and nitric oxide (NO) synthesis in human umbilical vein endothelial cells. High D-glucose (25 mmol/L, 2 minutes) induced membrane hyperpolarization and an increase of L-arginine transport (Vmax 6.1±0.7 versus 4.4±0.1 pmol//μg protein per minute) with no change in transport affinity (Km 105±9 versus 111± 16/μmol/L). L.-[3H]Citrulline formation and intracellular cGMP, but not intracellular Ca2+, were increased by high D-glucose. The effects of D-glucose were mimicked by levcromakalim (ATP-sensitive K+ channel blocker), paralleled by p42/p44mapk and Serr1177 -endothelial NO synthase phosphorylation, inhibited by NG-nitro-L-arginine methyl ester (L-NAME; NO synthesis inhibitor), glibenclamide (ATP-sensitive K+ channel blocker), KT-5823 (protein kinase G inhibitor), PD-98059 (mitogen-activated protein kinase kinase 1/2 inhibitor), and wortmannin (phosphatidylinositol 3-kinase inhibitor), but they were unaffected by calphostin C (protein kinase C inhibitor). Elevated D-glucose did not alter superoxide dismutase activity. Our findings demonstrate that the human fetal endothelial L-arginine/NO signaling pathway is rapidly activated by elevated D-glucose via NO and p42/44mapk. This could be determinant in pathologies pathologies in which rapid fluctuations of plasma D- glucose may occur and may underlie the reported vasodilatation in early stages of diabetes mellitus.