Functional assessment of extracorporeally perfused kidneys using drug loading tests

Extracorporeal organ perfusion has attracted attention for its potential to address several issues in organ preservation and transplantation. In this study, we aimed to identify a reliable method for evaluating kidneys undergoing extracorporeal perfusion, focusing specifically on the applicability of drug loading tests. Porcine kidneys obtained from a slaughterhouse were used to model organ damage following 3 hours of circulatory arrest. Kidneys were subjected to loading tests with circulatory agonists including adrenaline, verapamil, and nitroglycerin. In addition, renal function was assessed via loading tests with inulin, phenolsulfonaphthalein (PSP), and fluorescein isothiocyanate (FITC)-labeled albumin. In the circulatory experiments, vascular responses (i.e., changes in perfusion rate and vascular resistance) were observed in all cases despite severe ischemic damage. Among them, responses to adrenaline were observed even in highly injured kidneys that had undergone 18 hours of extracorporeal perfusion in addition to 3 hours of ischemia. Despite differences in the in vivo situation, the glomerular filtration rate (GFR) of inulin, rate of PSP excretion, and drug clearance could be measured quantitatively in the renal function experiments. These findings indicate that drug loading tests may be effective for both qualitative and quantitative assessment of vascular function and renal filtration capacity in extracorporeally perfused kidneys. Given that these assessments can aid in determining the degree of damage and residual function, they will likely be useful for evaluating extracorporeal perfused kidneys. in the future.