Introduction
Chronic kidney disease (CKD) is associated with a high cardiovascular risk and the development of vascular calcification (VC), an active process characterized by the phenotypic transition of vascular smooth muscle cells (VSMCs) toward an osteogenic phenotype, together with alterations in the extracellular matrix (ECM).1,2 The potassium channel Kv1.3 has been implicated in VSMC proliferation, migration, and phenotypic modulation (PM).3 We previously demonstrated that uremic serum increases its expression and that its inhibition partially attenuates calcification in vitro.4 In this study, we investigated its role in early uremia-induced vascular remodeling using an ex vivo model.
Materials and methods
Aortic rings from C57BL/6 wild-type (WT) and Kv1.3−/− mice were used and cultured ex vivo and incubated with either control serum (CS) or 10% human uremic serum (US), in the presence or absence of the selective Kv1.3 inhibitors PAP-1 and margatoxin. Human samples were obtained with informed consent and institutional ethical approval, and all animal procedures were performed in accordance with European Directive 2010/63/EU and the regulations of the University of Valladolid.
Results
US induced a loss of the contractile VSMC phenotype, with decreased calponin (CNN1) and increased expression of osteogenic markers, including osteopontin (OPN) (n=6 mice; p<0.01) and alkaline phosphatase (ALPL) (n=6 mice; p<0.001). The increase in ALPL was attenuated by PAP-1 (p<0.001), suggesting the involvement of Kv1.3 in early osteogenic activation.
Functionally, WT aortic rings showed a significant increase in stiffness after exposure to uremic serum (n=7; p<0.01), an effect that was reduced by Kv1.3 inhibition. In contrast, Kv1.3−/− vessels did not show significant changes in elasticity between conditions.
ECM analysis revealed increased disorganization of elastin fibers in vessels treated with uremic serum, an effect reversed by pharmacological Kv1.3 inhibition and absent in Kv1.3−/− vessels. Ongoing studies using atomic force microscopy are further characterizing the local biomechanical alterations associated with these structural changes.
Conclusion
Our findings support the concept that Kv1.3 acts as a key regulator of early uremia-induced vascular remodeling. Its inhibition or absence attenuates VSMC osteogenic transition, preserves ECM organization, and prevents increased arterial stiffness. These results support the role of Kv1.3 in early stages of CKD-associated vascular calcification and its potential as a therapeutic target.