title: Rat small mesenteric artery function after hindlimb suspension.
abstract: To determine whether simulated microgravity in rats is associated with vascular dysfunction, we measured responses of isolated, pressurized mesenteric resistance artery segments (157- to 388-microm ID) to vasoconstrictors, pressure, and shear stress after 28-day hindlimb suspension (HS). Results indicated no differences between HS and control (C) groups in 1) sensitivity or maximal responses to vasoconstrictors (norepinephrine, phenylephrine, serotonin, KCl); 2) ID, external diameter, or ratio of wall thickness to ID; 3) distensibility; or 4) vasodilatory responses to shear stress. Myogenic tone was attenuated (P < 0.05) in HS arteries vs. C, as evidenced by 1) decreased magnitude of tone in larger vessels (second-order branch off superior mesenteric artery, 261- to 388-microm ID) at pressures >/=40 mmHg in the presence of phenylephrine (10(-7) M) and 2) decreased magnitude of tone in smaller vessels (third-order branch off superior mesenteric artery, 157- to 277-microm ID), which exhibited spontaneous tone, at pressures > or =70 mmHg. This attenuation of myogenic tone after HS could contribute to orthostatic intolerance because myogenic tone contributes to the overall tone of resistance arteries.
authors.affiliation: Department of Physiology and Biophysics, University of Iowa, Iowa City, Iowa 52242, USA.
authors.forename: R C
authors.initials: RC
authors.lastname: Looft-Wilson
authors.forename: C V
authors.initials: CV
authors.lastname: Gisolfi
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001794:Blood Pressure; D019417:Hindlimb Suspension / Q000502:physiology*; D066298:In Vitro Techniques; D008297:Male; D008638:Mesenteric Arteries / Q000187:drug effects / Q000502:physiology*; D018482:Muscle, Skeletal / Q000098:blood supply / Q000187:drug effects / Q000502:physiology*; D009638:Norepinephrine / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012701:Serotonin / Q000494:pharmacology; D014655:Vascular Resistance / Q000187:drug effects; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology
chemical_list: D012701:Serotonin; D011189:Potassium Chloride; D000109:Acetylcholine; D009638:Norepinephrine