Sex-specific differences in vascular circulation and metabolic regulation associated with aging and cardiovascular health problems

The Flow Mediated Skin Fluorescence-Post-Occlusive Reactive Hyperemia (FMSF-PORH) technique proves that the skin can serve as an easily accessible and sensitive model for monitoring systemic redox changes in the NADH/NAD⁺ balance. The three most important diagnostic parameters of the method are related to the response to transient ischemia. Hyperemic Response (HRmax) characterizes the hyperemia phase and reflects the rapid increase in macrocirculatory blood flow after occlusion of the brachial artery. Hypoxia Sensitivity (HS) characterizes the reperfusion phase, by assessing the activation of myogenic microcirculatory oscillations. Ischemic Response (IRmax) is related to the ischemia phase and reflects the adaptation of cellular metabolism to ischemia. All three FMSF-PORH parameters depend on health condition and age. Sex-specific differences in the FMSF-PORH parameters are not seen in young healthy individuals, but appear with cardiovascular health problems and/or advanced age. Females compared to males have a significantly lower the IRmax parameter, characterizing metabolic (mitochondrial) regulation. In contrast, the HRmax parameter, characterizing macrocirculation, is higher in females than in males. All parameters slowly deteriorate with age and cardiovascular health problems. The results of this study highlight the need for a sex-specific perspective on vascular and metabolic health, as well as differentiated preventive healthcare strategies.