High-speed photoacoustic monitoring of vascular changes during acute hyperglycemia

Blood glucose (BG) level is one of the cardiovascular indicators that must be kept within a certain range. The importance of BG management is rising as clinical results have recently been reported that a vicious cycle of spikes and drops in BG levels, called a BG roller coaster, causes vascular dysfunction, increasing the risk of cardiovascular diseases. To investigate how elevated BG affects blood vessels, we photoacoustically monitored time-dependent changes in vascular diameters after intraperitoneal glucose injection in normal rats. Every 5 minutes, vascular networks were visualized using high-speed photoacoustic microscopy, their vascular diameters were calculated, and finally, the changes in vascular diameter were quantified. Arterioles constricted as the BG level increased, and then recovered as the BG level saturated. In the meantime, venules maintained their diameters. These results show that sudden transition to a hyperglycemic state may cause the arterioles to be constricted. The first direct observation of arterioles' rapid vasoconstriction due to acute hyperglycemia and spontaneous recovery in this study would be used as meaningful evidence to study the effects of BG level on the cardiovascular system.