Measuring Retinal Vessel Diameter from Mouse Fluorescent Angiography Images

Carbonic anhydrase, its inhibitors and vascular function

“…The retinal circulation is a true end artery system, with all the blood from the retinal arteries passing via the capillary beds to retinal venules and the central retinal vein. With fundus imaging, the retinal circulation can be easily viewed and examined, and structural and functional parameters such as vessel diameter ( Pedersen et al, 2005 ; Daníelsson et al, 2022 ; García-Llorca et al, 2023 ) and alterations in blood flow ( Marino et al, 2021 ) can be readily measured. The retinal vasculature tends to maintain a steady level of blood flow and oxygenation in the retina, by intrinsic autoregulation ( Riva et al, 1981 ; Dumskyj et al, 1996 ) in response to changes in perfusion pressure, intraocular pressure, or blood gasses (la Cour et al, 2000 ), but the myogenic response, considered to be the basis of autoregulation, is held to be intrinsic to vascular smooth muscle cells ( Davis and Hill, 1999 ).…”

“…It seems however that extracellular CA isoforms, or binding sites on membrane bound isoforms outside the cytosol are unlikely to play a role in regulation of vascular tone function, since only membrane permeable CAIs elicit the vasodilation. Indeed, membrane impermeable CAIs like the compounds depicted in Figure 1C of types 15-17, which are again benzenesulfonamides, but possessing positively charged moieties at the physiological pH due to their biguanidyl functionalities, are not able to induce vasodilation in isolated pre-contracted porcine retinal arterial segments (Eysteinsson et al, 2023).…”