Effect of glucose on corneal endothelial ATPase assays

Abstract

Background: previous biochemical methods of determining corneal endothelial ATPase (adenosine triphosphatase) activity have excluded glucose from incubation media. As glucose is an important metabolite for the formation of adenosine triphosphate (ATP) it is possible that glucose may be required in incubations investigating ATPase activity. Methods: standard ATP hydrolysis assays for ATPase activity were performed on bovine corneal endothelial homogenates using incubation media glucose levels of zero, 10, 20 and 30 mM. Results: corneal endothelial Na,K ATPase activity was not significantly different at the four glucose levels tested. Corneal endothelial Mg++ ATPase activity was significantly reduced (13.8 per cent) in the 10, 20 and 30 mM glucose conditions when compared to the zero glucose condition. Conclusions: corneal endothelial Na,K ATPase activity is unaffected by short-term exposure to hyperglycaemic media. While the data of this study are not conclusive, it is possible that short-term exposure of corneal endothelia to glucose may be associated with a transient decrease in Mg++ ATPase activity. Interactions between cellular ATP levels and Mg++ ATPase activity may have a role in helping regulate Na,K ATPase activity. (Clin Exp Optom 1994; 78: 1: 21–23)