Spatial landscape of oxygen in and around microvasculature during epileptic events.

Measuring changes in cerebral oxygen in tissue microdomains during epilepsy is important to identify hypoxic potential. Here, using a custom-built two-photon microscopy system, we present microscopic measurements of oxygen partial pressure ([Formula: see text]) in cortical microvessels and tissue of anesthetized mice during 4-aminopyridine (4-AP)-induced epileptic seizures. Investigating epileptic events, we characterized the distribution of the "initial dip" in [Formula: see text] in arterioles, venules, and tissue near the 4-AP injection site. Our results reveal a correlation between the percent change in [Formula: see text] during the "initial dip" and the diameter of nearest arterioles and venules.