Fig. 5.

Vasomotor responses in ex vivo retinas. (A) Arterioles with lumens of 8–15 µm were monitored during exposure to a deoxygenated perfusate (hypoxia), the NO donor sodium nitroprusside (100 µM), 5 µM adenosine, or 40 mM lactate. Responses to hypoxia and lactate were also tested in the presence of an inhibitor of monocarboxylate transporters, CHC (1 mM), and an NCX inhibitor, OMR-10103 (5 µM). (B) Images of an arteriole within an ex vivo P17 ROP retina before, during, and 5 min after exposure to a deoxygenated bathing solution. Asterisks denote a contracting abluminal cell, whose original position before hypoxia is shown by the dotted lines. At the site of maximal narrowing (arrows), the lumen decreased from 10.2 µm to 8.8 µm during hypoxia. In contrast to the compensatory vasodilation observed in control retina, the suprahyperpolarized vasculature of <P30 ROP retinas respond to hypoxia with an anomalous vasoconstriction.