title: Effects of ischemia and myogenic activity on active and passive mechanical properties of rat cerebral arteries.
abstract: Passive (papaverine induced) and active (spontaneous pressure induced) biomechanical properties of ischemic and nonischemic rat middle cerebral arteries (MCAs) were studied under pressurized conditions in vitro. Ischemic (1 h of occlusion), contralateral, and sham-operated control MCAs were isolated from male Wistar rats (n = 22) and pressurized using an arteriograph system that allowed control of transmural pressure (TMP) and measurement of lumen diameter and wall thickness. Three mechanical stiffness parameters were computed: overall passive stiffness (beta), pressure-dependent modulus changes (E(inc,p)), and smooth muscle cell (SMC) activity-dependent changes (E(inc,a)). The beta-value for ischemic vessels was increased compared with sham vessels (13.9 +/- 1.7 vs. 9.1 +/- 1.4, P < 0.05), indicating possible short-term remodeling due to ischemia. E(inc,p) increased with pressure in the passive vessels (P < 0.05) but remained relatively constant in the active vessels for all vessel types, indicating that pressure-induced SMC contractile activity (i.e., myogenic reactivity) in cerebral arteries leads to the maintenance of a constant elastic modulus within the autoregulatory pressure range. E(inc,a) increased with pressure for all conditions, signifying that changes in stiffness are influenced by SMC activity and vascular tone.
authors.affiliation: Department of Mechanical Engineering and Department of Neurology, The University of Vermont, Burlington 05405, USA.
authors.forename: Rebecca J
authors.initials: RJ
authors.lastname: Coulson
authors.forename: Naomi C
authors.initials: NC
authors.lastname: Chesler
authors.forename: Lisa
authors.initials: L
authors.lastname: Vitullo
authors.forename: Marilyn J
authors.initials: MJ
authors.lastname: Cipolla
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D001794:Blood Pressure / Q000502:physiology; D004195:Disease Models, Animal; D004548:Elasticity / Q000187:drug effects; D066298:In Vitro Techniques; D002546:Ischemic Attack, Transient / Q000503:physiopathology*; D008297:Male; D020768:Middle Cerebral Artery / Q000187:drug effects / Q000503:physiopathology*; D009129:Muscle Tonus / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000503:physiopathology; D010208:Papaverine / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D013314:Stress, Mechanical; D014654:Vascular Patency; D014661:Vasoconstriction / Q000187:drug effects; D014665:Vasodilator Agents / Q000494:pharmacology
chemical_list: D014665:Vasodilator Agents; D010208:Papaverine