Original Article Humoral signalling compounds in remote ischaemic preconditioning of the kidney, a role for the opioid receptor

Background. Renal ischaemia–reperfusion injury (IRI) is a common clinical problem associated with significant mortality and morbidity. One strategy to reduce this damage is remote ischaemic preconditioning (RIPC), in which brief ischaemia of a limb protects the kidney against a prolonged ischaemic insult. The mechanism of renal RIPC has not yet been elucidated. Here, we address the gap in our understanding of renal RIPC signalling, using a rat model of renal IRI and RIPC by brief hind limb ischaemia. Methods. Rats were treated with either no RIPC, RIPC + vehicle or RIPC+ an inhibitor or antagonist of one of the following candidate signalling molecules: noradrenalin, cannabinoids, glucocorticoids, inducible nitric oxide synthase, calcitonin gene-related peptide, ganglion