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. 2022 Apr 15;23(1):146.
doi: 10.1186/s12882-022-02780-0.

Corticomedullary shunting after ischaemia and reperfusion in the porcine kidney?

Michael Rehling  1   2 , Stine Gram Skjøth  1   2 , Jørgen Frøkiær  1   2 , Lene Elsebeth Nielsen  1   2 , Christian Flø  1 , Bente Jespersen  2   3 , Anna Krarup Keller  4   5
Affiliations

Corticomedullary shunting after ischaemia and reperfusion in the porcine kidney?

Michael Rehling et al. BMC Nephrol. .

Abstract

Background: Renal perfusion may redistribute from cortex to medulla during systemic hypovolaemia and after renal ischaemia for other reasons, but there is no consensus on this matter. We studied renal perfusion after renal ischaemia and reperfusion.

Methods: Renal perfusion distribution was examined by use of 153Gadolinium-labeled microspheres (MS) after 2 h (hrs) and 4 h ischaemia of the pig kidney followed by 4 h of reperfusion. Intra-arterial injected MS are trapped in the glomeruli in renal cortex, which means that MS are not present in the medulla under normal physiological conditions.

Results: Visual evaluation after reperfusion demonstrated that MS redistributed from the renal cortex to the medulla in 6 out of 16 pigs (38%) subjected to 4 h ischaemia and in one out of 18 pigs subjected to 2 h ischaemia. Central renal uptake of MS covering the medullary/total renal uptake was significantly higher in kidneys subjected to 4 h ischaemia compared with pigs subjected to 2 h ischaemia (69 ± 5% vs. 63 ± 1%, p < 0.001), and also significantly higher than in the contralateral kidney (69 ± 5% vs. 63 ± 2%, p < 0.001). Analysis of blood and urine demonstrated no presence of radioactivity.

Conclusion: The study demonstrated the presence of MS in the renal medulla in response to renal ischaemia and reperfusion suggesting that severe ischaemia and reperfusion of the pig kidney leads to opening of functional shunts bypassing glomeruli.

Keywords: Microspheres; Renal blood flow; Renal ischaemia; Renal perfusion; Renal redistribution; Renal shunts.

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Conflict of interest statement

The authors declare that they have no competing interests.

Figures

Fig. 1
Fig. 1
Distribution of radio-labeled microspheres in a pig after renal ischaemia and reperfusion In comparison to the non-ischaemic right kidney, the left kidney shows an increased uptake of radio-labeled microspheres in renal medulla relative to the total kidney
Fig. 2
Fig. 2
Comparison of methods for the study of distribution of radio-labeled microspheresThe figure shows a positive correlation between visual distribution score grade 1–3 and the measured fraction of microspheres in the central kidney including medulla relative to the entire kidney (r2 = 0.98). Differences between 2 and 4 h ischaemia is marginally significant (p ~ 0.08). Grade 0 is a homogeneous pattern similar to control kidneys and Grade 3 is a pattern clearly showing the medullary architecture and the anatomical outline of calyces
See this image and copyright information in PMC

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