Cardiomyocytes' prolonged IL-2 incubation induces enhancement in L-type Ca2+channels mediated by inhibitory-kappaB kinase/nuclear factor-kappaB signalling

The main objective of this study was to determine the primary intracellular signalling pathway affected by prolonged (2 hours) incubation in interleukin-2 (IL-2). Based on the inflammatory nature of IL-2, priority was given to the involvement of inhibitory-kappaB kinase/nuclear factor-kappaB (IKK/NF-kappa B) signalling. All of the experiments were performed on freshly prepared cardiomyocytes isolated from rat left ventricles. After isolation, the whole-cell voltage-clamp recordings were performed on single cells. After 2 hours of incubation in IL-2, the current at 0 mV was approximately 100% higher than at the start of the incubation. ACHP, a highly specific kinase beta inhibitor, in a concentration of 10 nmol/L, caused significant reduction in the I-Ca,I-L. IL-2 (2 ng/mL) in the presence of 0.1 mu mol/L IMD-0354 as a specific inhibitor of IKK beta, caused nearly no changes in the I-Ca,I-L. IL-2 (3 ng/mL) induced a significant increase in phosphorylated NF-kappa B p65. The cardiomyocytes incubated in a Kraftbruhe solution containing IL-2 plus PDTC as a specific inhibitor of inducible nitric oxide synthase (iNOS) for 2 hours had a similar I-Ca,I-L increase compared to the cells incubated only in IL-2. IL-2-induced enhancement inL-type Ca2+ channels was mediated by IKK/NF-kappa B signalling, but not via iNOS-mRNA signalling.