In this work, we use contrast agents cationic ferritin and gadolinium-DTPA (Gd-DTPA) to visualize dynamics of macromolecules and freely filtering particles in individual nephrons throughout entire perfused rat kidneys. Further, we also look at dynamics in kidneys that received a vasoconstriction agent, angiotension II (AngII). Voxel time courses were fitted with a bi-exponential model for each experiment (Experiment I, CF infusion and Experiment II, Gd-DTPA bolus). From fitting we assess CF uptake rates and measure single nephron glomerular filtration rate (snGFR). CF uptake rates and values of snGFR were mapped spatially and observed to be heterogeneously distributed throughout the kidney.