Rapid Stimulation of <scp>l</scp> -Arginine Transport by <scp>d</scp> -Glucose Involves p42/44 ^mapk 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 (V(max) 6.1+/-0.7 versus 4.4+/-0.1 pmol/ microg protein per minute) with no change in transport affinity (K(m) 105+/-9 versus 111+/-16 micromol/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/p44(mapk) and Ser(1177)-endothelial NO synthase phosphorylation, inhibited by N(G)-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 p42/44(mapk). This could be determinant in pathologies in which rapid fluctuations of plasma D-glucose may occur and may underlie the reported vasodilatation in early stages of diabetes mellitus.