Intravital Videomicroscopy

The assessment of single-nephron glomerular function is essential for understanding the fundamental regulatory mechanisms of renal hemodynamics (1 ). In earlier studies, special tracer techniques using fluorescence-labeled erythrocytes, radiolabeled microspheres, and dye solutions were used for analysis of renal hemodynamics. However, it was extremely difficult to perform direct in vivo observation of renal microcirculation. Recently, glomerular function has been directly evaluated with the use of the isolated perfused glomerulus (2 –4 ), juxtamedullary nephrons (5 ), and hydronephrotic kidneys (6 ,7 ). These approaches require invasive manipulations and/or some special animal models that may alter physiologic renal vascular responsiveness, and may thus confound the characterization of these renal vessels.