Reactivity of the Arteries of the Cranial Pia Mater in Old Rats after Experimental Myocardial Infarction

In 24-month-old male Wistar rats, the endothelium-dependent (ED) and endothelium-independent (EI) responses of the arteries of the cranial pia mater (CPM) of branching orders I-V were studied by vital microscopy 30 days after the modeling of myocardial infarction. Sham-operated animals were used as a control. In both groups, a distinct response of the CPM vessels of different branching orders to vasodilators was observed: in pharmacological tests (acetylcholine, nitroglycerin), a dependence of the ED or EI vascular reactivity on the diameter of the arteries was found. In orders I-II branches, the myogenic ED response predominates, and the EI response of the vessels prevails in orders IV-V branches. In order III branches, both mechanisms were approximately equally developed. In most cases, the vascular reactivity and numerical density of arteries that changed their diameter were significantly lower in rats with myocardial infarction compared to control animals. Thus, in myocardial infarction, systemic disorders of the ED and EI reactivity of the CPM vessels of different diameters caused by endothelial dysfunction have been identified; the combination of these disorders with age-related changes determined rapid depletion of adaptive reserves and increased circulatory hypoxia in the brain. These processes lead to neurodegenerative changes, primarily in the oxygen-sensitive neurons of the frontal cortex, and to cognitive impairments.