Nitric-oxide-induced inhibition of glyceraldehyde-3-phosphate dehydrogenase may mediate reduced endothelial cell monolayer integrity in an in vitro model blood-brain barrier

The process of nitric-oxide (NO)-induced cellular toxicity may involve ener gy deprivation since the radical is reported to prevent both mitochondrial oxidative phosphorylation and glycolysis. In order to determine whether the se processes are important in NO-induced blood-brain barrier (BBB) dysfunct ion, we used a cell culture model of the BBB and compared the effects of ga seous NO, potassium cyanide (KCN, a mitochondrial respiratory chain inhibit or) and iodoacetate [IA, an inhibitor of the glycolytic enzyme glyceraldehy de-3-phosphate dehydrogenase (GAPDH)] on endothelial cell ATP content, GAPD H activity and barrier integrity. NO lead to a rapid breakdown in model bar rier integrity and resulted in a reduction in endothelial cell ATP content and GAPDH activity. KCN had no effect on endothelial cell ATP content or ba rrier integrity, while IA, at a concentration that completely blocked endot helial cell GAPDH activity, resulted in a rapid decline in ATP content but did not lead to a decline in barrier integrity until at least 2 h of exposu re. These results indicate that inhibition of endothelial cell GAPDH activi ty rather than mitochondrial respiration causes an energy deficiency and de layed barrier dysfunction. However, the rapid detrimental effects of gaseou s NO on barrier integrity cannot be fully explained by endothelial cell ene rgy depletion and may be related to the actions of the free radical and its products on cellular lipids. (C) 2001 Elsevier Science B.V. All rights res erved.