3.2.3. Wire Myography

Wire myography is an in vitro technique that allows the monitoring of the functional responses and the vascular reactivity of small vessel segments. Different vessel beds from various species, in a variety of pathological disease states, can be investigated. Changes in the feasibility of dilatation provide information on endothelial dysfunction and analysis of further alterations in vascular reactivity is feasible. Moreover, the biomechanical and passive properties of the vessel, such as the vessel diameter, elasticity, and vascular compliance, can be investigated [111,112]. After vessel dissection and cleaning from the surrounding tissue, small vessel rings are clamped in a myograph chamber with an isometric technique. The investigated drugs are applied to the buffer in the measuring chamber. Standardized experimental conditions allow the examination of pharmacological differences between the vessels [112].

Kirsch et al. used wire myography as a functional assay to validate the histological and chemical analysis of uremia-induced vessel mineralization in mice. They found a reduced maximum contraction in mice fed a high-phosphate diet compared to the control animals [113]. Similar results were found in a rat model of adenine-induced renal failure, where the rate of aortic relaxation was reduced in CKD rats compared to control animals [114]. The contraction rate was also reduced in mesenteric arteries and aorta in the CKD group compared to control rats [114]. Although in this study no vascular calcification could be detected, possibly because CKD induction for less than ten weeks by adenine diet with gradually reduced adenine concentration, it shows that the aorta is affected and the rate of relaxation is reduced [114]. In an Abcc6^−/− mouse model, wire myography was used to describe the vessel contraction potential, which was not altered, although calcium deposits and osteogenic trans-differentiation occurred in VSMC [52].

In conclusion, functional biomarkers for the description of vessel stiffness are widely used in the clinical situation. Up to now, only a few studies have used this for animal models. As mentioned above, a precise prediction of vascular calcification from functional markers is not easily given. However, a longitudinal approach is possible and therefore might help to get further information of vessel function in animals and potential changes under the treatment procedure, thus helping to find the right time point and renders the possibility for reducing the animal number.