Alterations to the middle cerebral artery of the hypertensive-arthritic rat model potentiates intracerebral hemorrhage.

aimsWe have recently created an age-dependent hypertensive-mono-arthritic animal model from the stroke-resistant spontaneously hypertensive rat to model populations with autoimmune disease who are hypertensive and are prone to stroke. The model exhibits signs of hemorrhagic stroke (HS) subsequent to chronic inflammation and hypertension. HS is also associated with the inability of middle cerebral arteries to undergo pressure dependent constriction (PDC). We investigated alterations in the cerebrovasculature of our hypertensive mono-arthritic animals that develop stroke. MAIN

methodsAnimals were fed either a high salt diet (HSD) (4% NaCl) or Purina chow (0.58% NaCl) from weaning. Complete Freund's Adjuvant (CFA) was injected into the left hind paw at 21-28 weeks; controls received saline and histological and functional studies were performed.

resultsBrain damage was more prominent with the high salt, with inflammation exacerbating the damage. High salt alone significantly decreased middle cerebral artery's (MCA's) ability to undergo PDC. Inflammation significantly decreased the ability of cerebrovasculature to respond to pressure step in the regular salt diet. The responses to vasoactive peptides were also significantly attenuated in both inflamed groups regardless of diet.

conclusionInduction of chronic systemic inflammation increases brain damage, and affect the MCA's vasogenic function, decreasing its ability to respond to intraluminal pressure. HSD further exacerbates organ damage associated with chronic inflammation, further compromising cerebrovascular function, and likely increasing the incidence of intracerebral hemorrhage and injury.