Late preconditioning in rat retina: involvement of adenosine and ATP-sensitive K(+) channel.

To determine whether stimulation of adenosine receptors and opening of ATP-sensitive K(+) channels were involved in the protective effect of late preconditioning in the rat retina, rats were subjected to 60 min of retinal ischemia, and ischemic preconditioning was achieved by applying 5 min of ischemia 24 h before 60 min of ischemia. In non-preconditioned rats, cell loss in the ganglion cell layer and thinning of the inner plexiform and inner nuclear layer were observed 7 days after 60 min of ischemia. Ischemic preconditioning completely prevented the retinal tissue damage and 8-phenyltheophylline or 5-hydroxydecanoate reduced the protective effect of ischemic preconditioning. Therefore, stimulation of adenosine receptors and opening of ATP-sensitive K(+) channels might be involved in the mechanism of histological protection by late preconditioning in the retina.