The effects of recruitment of renal functional reserve on renal cortical and medullary oxygenation in non‐anesthetized sheep
Alemayehu H. Jufar, Roger G. Evans, Clive N. May, Sally G. Hood, Ashenafi H. Betrie, Anton Trask‐Marino, Rinaldo Bellomo, Yugeesh R. Lankadeva
Abstract
Abstract Aim Recruitment of renal functional reserve (RFR) with amino acid loading increases renal blood flow and glomerular filtration rate. However, its effects on renal cortical and medullary oxygenation have not been determined. Accordingly, we tested the effects of recruitment of RFR on renal cortical and medullary oxygenation in non‐anesthetized sheep. Methods Under general anesthesia, we instrumented 10 sheep to enable subsequent continuous measurements of systemic and renal hemodynamics, renal oxygen delivery and consumption, and cortical and medullary tissue oxygen tension (PO 2 ). We then measured the effects of recruitment of RFR with an intravenous infusion of 500 ml of a clinically used amino acid solution (10% Synthamin® 17) in the non‐anesthetized state. Results Compared with baseline, Synthamin® 17 infusion significantly increased renal oxygen delivery mean ± SD maximum increase: (from 0.79 ± 0.17 to 1.06 ± 0.16 ml/kg/min, p < 0.001), renal oxygen consumption (from 0.08 ± 0.01 to 0.15 ± 0.02 ml/kg/min, p < 0.001), and glomerular filtration rate (+45.2 ± 2.7%, p < 0.001). Renal cortical tissue PO 2 increased by a maximum of 26.4 ± 1.1% ( p = 0.001) and medullary tissue PO 2 increased by a maximum of 23.9 ± 2.8% ( p = 0. 001). Conclusions In non‐anesthetized healthy sheep, recruitment of RFR improved renal cortical and medullary oxygenation. These observations might have implications for the use of recruitment of RFR for diagnostic and therapeutic purposes.