Adenosine-stimulated production of sugar-phosphates in bovine corneal endothelium.
Exogenous adenosine promotes deturgescence of in vitro corneal preparations, but the biochemical mechanism underlying this effect has yet to be elucidated. This study sought to investigate the possibility that adenosine promotes deswelling by activating the pentose shunt in corneal endothelium. Homogenized extracts of bovine corneal endothelial tissue cultures were incubated with [32P]K2HPO4 in the presence or absence of 5 mM adenosine for periods up to 30 min. Radiolabelled sugar-phosphates were separated on polyethyleneimine-cellulose thin layers, autoradiographed, removed, and counted by liquid scintillation. At 30 min, radiolabelled ribose-1-phosphate (R-1-P), ribose-5-phosphate (R-5-P), and sedoheptulose-7-phosphate (S-7-P) were identified and found to be significantly higher than control (without adenosine) levels by factors of 2.7, 4.2, and 2.4, respectively. The increases occurred first for the ribose-phosphates and later for sedoheptulose-7-phosphate. These results suggest that exogenous adenosine activates the pentose shunt by contributing its ribose moiety as a substrate, which may ultimately provide cellular energy for the deturgescence mechanism.
D000241:Adenosine / Q000378:metabolism / Q000494:pharmacology*; D000818:Animals; D001345:Autoradiography; D002417:Cattle; D003315:Cornea / Q000187:drug effects / Q000378:metabolism*; D046508:Culture Techniques; D004727:Endothelium / Q000187:drug effects / Q000378:metabolism; D006019:Glycolysis; D010429:Pentoses; D010766:Phosphorylation; D012267:Ribosemonophosphates / Q000096:biosynthesis; D013403:Sugar Phosphates / Q000096:biosynthesis*
D010429:Pentoses; D012267:Ribosemonophosphates; D013403:Sugar Phosphates; C031154:ribose 1-phosphate; C020495:sedoheptulose 7-phosphate; C031626:ribose-5-phosphate; D000241:Adenosine