Null effect of adenosine on cyclic nucleotides of the corneal endothelium: possible implications for adenosine-stimulated corneal deturgescence.

Adenosine has been reported by several investigators to stimulate corneal deturgescence, but the actual biochemical mechanism of this effect remains unknown. Effects observed include increased magnitude and rate of corneal thinning, increased endothelial fluid transport rate, support of adenosine triphosphate (ATP) levels, stimulation of magnesium activated ATPase (Mg++ATPase) and sodium-potassium activated ATPase (Na+K+ ATPase) activities in endothelium whole cell preparations, but a lack of stimulation of Mg++ATPase and Na+K+ATPase activities in endothelial plasma membrane preparations. This study examined the possibility that adenosine alters the corneal endothelial levels of two biochemical effectors: adenosine 3',5'-cyclic monophosphate (cAMP) and guanosine 3',5'-cyclic monophosphate (cGMP). Bovine corneal endothelium was studied as fresh tissue and after growth in tissue culture. The samples were processed both at room temperature and in liquid nitrogen. Incubation of fresh and cultured endothelia in media containing adenosine was found to have no effect on the cAMP and cGMP levels regardless of the processing method. The data suggest that cyclic nucleotides do not mediate adenosine-stimulated corneal deturgescence.