Nifedipine improves recovery function of kidneys preserved in a high-sodium, low-potassium cold-storage solution: study with the isolated perfused rat kidney technique

Extracellular types (high-Na) of cold-storage solution (CSS) have been shown to be more effective in preserving kidneys than intracellular CSS (high-K). On the other hand, calcium entry blockers (CEB) have been demonstrated to improve graft function when administered after and/or prior to transplantation. The ischaemia reperfusion syndrome involves, in part, an alteration in intracellular calcium metabolism that induces an increase in renal vascular resistances (RVR) and other cellular dysfunction, and high-K CSS per se are vasoconstrictive. Since CEB act via a modification in intracellular calcium metabolism on vascular smooth muscle, glomerular, and tubular cells, we evaluated the actual benefit on CEB on kidneys preserved in Belzer's CSS (K-UW) and a high-Na version of Belzer's CSS (Na-UW). The isolated perfused rat kidney (IPK) was used, first as a vascular bed to test the effects of CSS on RVR, and the influence of nifedipine. Second, the recovery function of the IPK was assessed by GFR and tubular Na reabsorption, after 24 h preservation in K-UW and Na-UW, with or without nifedipine. Results were compared with a control group in which renal function was measured without prior cold-storage. K-UW but not Na-UW induced an increase in RVR when flushed into the kidney. This vasoconstriction is prevented by nifedipine. K-UW CSS was more deleterious to renal function than Na-UW. Addition of nifedipine to the flush, the CSS for 24 h, and to the normothermic reperfusate further improved recovery function of the IPK cold stored in Na-UW but not in K-UW, without any modification of RVR. Nifedipine may be of potential effect in attenuating ischaemic injury by a mechanism which does not involve its vasodilatory properties.