Acute kidney injury is one of the most common serious complications of major surgery, yet clinicians currently have limited ability to predict which patients are most vulnerable. One challenge is that systemic blood pressure measurements do not necessarily reflect how well blood flow within the kidney is being maintained. The kidney has its own built-in protective mechanism, called renal autoregulation, which adjusts blood vessel resistance to help maintain stable blood flow as blood pressure rises or falls. Although this process is well characterized in animal models, it has not been directly quantified in humans.

In collaboration with UNT Health, our lab is developing a noninvasive approach to quantify renal autoregulation in humans by adapting analytical methods used to study blood flow regulation in the brain. Establishing this approach could provide a new way to identify patients who are particularly vulnerable to kidney injury, improve our understanding of how the kidney responds to physiological stress, and ultimately inform strategies to protect renal blood flow during surgery and other clinical conditions.

This project is funded by a UNT & UNT Health Interdisciplinary Team Sciences Award, “Development of a Novel Method to Quantify Human Renal Autoregulation.”

Remote Ischemic Preconditioning (RIPC) is a non-invasive intervention involving repeated cycles of blood pressure cuff inflation that has been shown to protect the heart, brain, and kidneys from injury in experimental models. However, large clinical trials have produced mixed results, in part because we still do not fully understand the biological signals responsible for its protective effects or why some patients benefit while others do not.

Using intranasal naloxone (Narcan) as an experimental tool, our lab provided the first evidence in humans that RIPC protects vascular function through endogenous opioids.

This study was published in the Journal of Applied Physiology and can be read here:
https://journals.physiology.org/doi/full/10.1152/japplphysiol.00913.2024

Building on this discovery, our current work seeks to determine where these opioids originate, how they mediate protection, and why some individuals may produce insufficient amounts or respond differently to them. Ultimately, these studies may help explain why RIPC is more effective in some individuals than others and inform more individualized approaches to implementing this intervention.