The Effects of Local Heating on Skin Microhemodynamics Regulation in Mice with a Genetic Model of Type 2 Diabetes Mellitus

The study investigated parameters of skin microcirculation in control mice and mice with a genetic model of type 2 diabetes mellitus (T2DM). In isoflurane-anesthetized animals, the dynamics of skin microcirculation on the right hind paw pad were measured using laser Doppler flowmetry at rest and in response to local heating up to 40°C. The integral microcirculatory index (MI) was assessed as the average MI value over 15 min at rest and during the thermal test. Adaptive spectral wavelet analysis was performed in four frequency intervals: endothelial (0.008–0.016 Hz), neurogenic (0.016–0.05 Hz), myogenic (0.05–0.2 Hz), and Mayer-wave-associated (0.2–1 Hz). The degree of linear statistical relationship between the spectral components of skin microhemodynamics was determined using Spearman’s rank correlation coefficients. Local heating caused a significant increase in the integral MI in both control and T2DM animals compared to rest. In the control group, local heating led to a significant increase in the normalized oscillation amplitudes in the myogenic and Mayer-wave intervals, whereas in the T2DM group, they increased only in the Mayer-wave interval. At rest, the contribution of myogenic oscillations to the total energy of oscillations in the T2DM group, was significantly higher, while the contribution of Mayer-wave oscillations was significantly lower compared to controls. In T2DM animals, local heating considerably reduced the number of statistically significant internal couplings between the spectral components of microcirculatory blood flow oscillations by 1.1 times, and their strength by 1.2 times, whereas in the control group, the thermal test, on the contrary, led to an increase in both these parameters by 1.4 and 1.3 times, respectively. The obtained results demonstrate that mice with a genetic model of T2DM can be successfully employed to analyze the rhythmic components of peripheral skin microhemodynamics under the influence of various stimuli.