Cell injury after ischemia and reperfusion in the porcine kidney evaluated by radiolabelled microspheres, sestamibi, and lactadherin

Corticomedullary shunting after ischaemia and reperfusion in the porcine kidney?

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.

Old tracer for a new purpose: potential role for 99mTc-2-Methoxyisobutylisonitrile (99mTc-MIBI) in renal transplant care

AIM

Calcineurin inhibitors are substrates for P-glycoprotein (P-gp), the expression of which is associated with ABCB1 C3435T polymorphism. Individual P-gp response to calcineurin inhibitor may be linked to nephrotoxicity or rejection. Tc-2-Methoxyisobutylisonitrile (Tc-MIBI) is also a P-gp substrate. The aim of this study, therefore, was to determine Tc-MIBI organ kinetics and compare them with ABCB1 genotype with a view to replacing Tc-mercaptoacetyltriglycine (Tc-MAG3) with Tc-MIBI in renal transplant care.

METHODS

Thirty prospective donors (13 male) were imaged for 20 min after administration of Tc-MIBI (400 MBq) intravenously. Posterior images of the abdomen were acquired at 30 and 120 min. Organ 30 min/peak count rate ratios and exponential two-point (30-120 min) rate constants (k, min) were calculated. Nineteen donors were genotyped for C3435T (exon 26), G2677T (exon 21), C1236T (exon 12), and G1199A (exon 11) ABCB1 polymorphisms using a PCR-based technique.

RESULTS

Tc-MIBI and Tc-MAG3 gave similar perfusion images. Although their patterns of renal elimination were different, differential renal function was not significantly different. There was a negative trend between the hepatic 30 min/peak ratio and C3435T genotype (CC: 0.8374 ± 0.0502; TC: 0.6806 ± 0.1300; TT: 0.6919 ± 0.1506; P=0.083). Renal k showed a negative trend with C3435T (CC: 0.0021 ± 0.0020; TC: 0.0037 ± 0.0013; TT: 0.0040 ± 0.0012 min; P=0.087) but with no other genotypes. There were no significant sex-related differences in Tc-MIBI kinetics.

CONCLUSION

Tc-MIBI can replace Tc-MAG3 for pretransplant workup. The ABCB1 C3435T polymorphism may influence Tc-MIBI kinetics and thus have a role in renal transplant care. Further prospective trials are required to establish the full potential of Tc-MIBI in renal transplant management.