Effects of mannitol and iohexol infusions on the renal cortical blood flow in dehydrated mice

In vivo fluorescence microscopy was used in experimental studies of renal cortical microcirculation in mice. The effects of intravenous infusions of equimolar concentrations of mannitol and iohexol were studied in normal lean mice and obese/hyperglycemic mice after dehydration overnight. All infusions produced marked effects in distribution and velocity of renal cortical blood flow. Initially increased blood flow was seen in a number of capillaries after infusion of both mannitol and iohexol, and renal cortical blood flow was inhomogeneous for different capillaries. A significantly (p < 0.05) larger number of capillaries with decreased blood flow, within the first minutes after start of infusion, was observed after infusion of iohexol to normal mice when the animals had been dehydrated overnight. Our results indicate that the minor adverse effects on renal cortical blood flow caused by the infusion of contrast medium are potentiated by dehydration.