Vasodilatation Function of Cerebral Vessels at Arterial Hypertension in OXYS Rats

OXYS rats represent a selection strain of laboratory animals, which are characterized by the accelerated senescence. Substantial morphologic changes of cerebral vessels were revealed in the senescence-accelerated OXYS rats by the noninvasive MRI diagnostics using the induced arterial hypertension and the author's original methods. These changes appeared as vascular lesions with a thickening of the intimae and the increasing of the signal intensity from blood in cerebral vessels. Cerebral arterial hypertension in normotensive Wistar rats developed as result of intraperitoneal injections of hydrocortisone acetate and diet enriched by sodium ions. The pathology of cerebral vessels in OXYS rats began its development much earlier and was based on spontaneous hypertension in connection with initially elevated blood pressure as well as the genotype of the animals. Four different inductors (two vasodilators and two vasoconstrictors) were used in the study of the endothelium-independent and endothelium-dependent vasodilatation and vasoconstrictions. We have compared previously unknown effects of these inductors on cerebral vessels in senescence-accelerated OXYS rats and those in normal Wistar rats. The response of the arteries to the action of inductors showed changes in the status of anterior, middle, and posterior cerebral arteries of circle Willis. Thus, we have indicated the changes in compensatory and adaptive characters of arteries in hypertensive OXYS rats in comparison with hypertensive Wistar rats. Reduced vasodilator response in the middle cerebral arteries suggests an elevated risk for development of arterial hypertension in these rats.