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Abstract: SA-PO788

Mapping Tubuloglomerular and Myogenic Autoregulation Throughout the Kidney With MRI

Session Information

  • Hypertension and CVD: Mechanisms
    November 05, 2022 | Location: Exhibit Hall, Orange County Convention Center‚ West Building
    Abstract Time: 10:00 AM - 12:00 PM

Category: Hypertension and CVD

  • 1503 Hypertension and CVD: Mechanisms

Authors

  • Baldelomar, Edwin, Washington University in St Louis School of Medicine, St Louis, Missouri, United States
  • Charlton, Jennifer R., University of Virginia School of Medicine, Charlottesville, Virginia, United States
  • Keilholz, Shella, Washington University in St Louis School of Medicine, St Louis, Missouri, United States
  • Eldeniz, Cihat, Washington University in St Louis School of Medicine, St Louis, Missouri, United States
  • An, Hongyu, Washington University in St Louis School of Medicine, St Louis, Missouri, United States
  • Bennett, Kevin M., Washington University in St Louis School of Medicine, St Louis, Missouri, United States
Background

Autoregulation is a critical kidney function to protect nephrons, is disrupted in disease, and several autoregulatory mechanisms of perfusion have been observed in animal models, observed by distinct low-frequency oscillations (myogenic ~100mHz and tubuloglomerular feedback, TGF ~10mHz).

Methods

Rat Kidneys – Sprague Dawley rats (n=4) were anesthetized and left anatomical kidney externalized in three animals. MR Details: Bruker 9.4T MRI; a mouse brain receive only coil; single shot gradient echo echo planar imaging; TE/TR = 13/150ms; resolution = 0.4x0.4x0.4mm3; and 15min acquisition time. Vitals were monitored. In two animals, we compared scans with and without saturation bands over renal artery to assess oxygen sensitivity. We imaged one kidney in situ without externalization to determine if we could overcome motion. Imaging was repeated after euthanisia. Human Kidney In Vivo – A single human volunteer consented for imaging. MR Details: 3T Prisma scanner using a spine and a flex coil; FLASH sequence; TE/TR = 2.27/4.2ms; resolution = 2.5x2.5x2.5mm3; and 15min acquisition time. Post processing – AFNI and Matlab softwares were used to process and analyze data. Typical pre-processing methods were used.

Results

Resting state MRI and spectral analysis revealed spatially variable and distinct bands of frequencies consistent with myogenic and TGF autoregulatory mechanisms(Fig 1). We found evidence of other mechanisms of physiological function at lower frequencies that require further investigation. We observed evidence of spatial correlations in the time course consistent with nephrovascular coupling(Fig 1).

Conclusion

A simple and short, non- contrasted MRI scan can be used to detect spatially variable, low- frequency oscillatory changes that appear to be associated with autoregulation of the kidney in both rats and humans. Mapping autoregulatory spectra may be an important, unique biomarker of kidney disease, developmental processes, transplant evalutation, and response to therapies.

Funding

  • Private Foundation Support