Abstract: TH-OR011

New Intravital Imaging Technique Visualizes Renal ATP Dynamics during AKI Predicting Renal Prognosis

Session Information

Category: Acute Kidney Injury

  • 001 AKI: Basic

Authors

  • Yamamoto, Shinya, Kyoto University Graduate School of Medicine, Kyoto, Kyoto, Japan
  • Yamamoto, Masamichi, Kyoto University Graduate School of Medicine, Kyoto, Japan
  • Yanagita, Motoko, Kyoto University Graduate School of Medicine, Kyoto, Kyoto, Japan
Background

The kidney constantly produces and consumes adenosin 5’ triphosphate (ATP), and mitochondrial dysfunction, which leads to ATP depletion, plays an important role in the pathogenesis of renal diseases. In spite of importance of ATP dynamics, however, lack of technology has hindered further analysis. Here we established a novel ATP intravital imaging technique and analyzed whether the ATP dynamics during acute kidney injury (AKI) could predict the renal prognosis.

Methods

To enable intravital imaging of ATP dynamics, we generated a novel mouse line, which expressed the FRET-based ATP biosensor in all tissues. We visualized renal ATP dynamics at a single cell level in the physiological condition as well as in ischemic reperfusion (IR) model with two-photon microscope. Furthermore, we performed the quantification of fibrosis two weeks after IR, and assessed the correlation between the ATP recovery and fibrosis.

Results

The ATP levels in proximal tubules (PTs) rapidly decreased to the basal level in only 2 minutes after induction of ischemia, whereas the ATP levels in distal tubules (DTs) were maintained even after 30 minutes.
The ATP dynamics in PTs after reperfusion was variable depending on the duration of ischemic time. The ATP recovery in PTs after 15, 30, and 60 minute-IR took 2, 5, and 30 minutes to reach a peak plateau, and the % ATP recovery (recovery ATP/ initial ATP levels) were 90%, 83%, and 69%, respectively. The longer ischemic time led to slower and more insufficient ATP recovery in PTs. Interestingly, ATP recovery time and the % ATP recovery in DTs were 4 minutes and 90% even after 60 minute-IR, indicating the tolerance of DTs to ischemia.
The longer ischemic led to more significant renal fibrosis in chronic phase, and the fibrosis was inversely well correlated with the ATP recovery slopes in PTs in acute phase.

Conclusion

We, for the first time, succeeded in visualizing the spatiotemporal ATP dynamics in the kidney by generating a novel FRET-based ATP biosensor mice. We demonstrated the rapid reduction of ATP in PTs and the slow reduction in DTs after ischemia. After reperfusion, the rate and sufficiency of ATP recovery were dependent on the severity of injury, and the ATP dynamics in the acute phase might determine the outcome in chronic phase. We also confirmed the tolerance of DTs to ishemia from the point of ATP dynamics.