title: Sustained vessel dilation induced by increased pulsatile perfusion of porcine carotid arteries in vitro.
abstract: Arterial pulse pressure (PP) increases with exertional stress and ageing, and can modify vessel diameter in smaller vessels. To test if PP must exceed a certain range to influence vessel diameter, and determine if such effects are endothelium-dependent or intrinsic to vascular viscoelasticity, eight fresh excised porcine carotid artery segments were perfused with modified Krebs-Henseleit by a servo-controlled system generating physiological arterial pressure waveforms. In a separate group of vessels (n = 10), the endothelium was mechanically removed. Vessel external diameter was measured by video edge-detection. Vessels partially preconstricted with noradrenaline were perfused at 9 mL min(-1) mean flow, at mean pressure of 90 or 120 mmHg, and zero PP. PP alone was then increased to 40, 70, or 120 mmHg at 1 Hz cycling rate for 5 min, then returned to zero and vessel diameter measured immediately thereafter. The protocol was repeated after 10-20 min stabilization. Mean vessel diameter rose proportionally with PP only once PP exceeded 40 mmHg, with maximal increases of 6-9% at a PP of 120 mmHg. Similar responses were obtained in vessels with and without a functional endothelium, at both mean pressures. Thus, when exposed to higher than normal resting PP, conduit arteries dilate owing to the stress-relaxation response of their viscoelastic wall. This mechanism of PP-mediated vascular dilatation may contribute to enhanced organ perfusion when small resistance arteries are already dilated.
authors.affiliation: Department of Internal Medicine, The Johns Hopkins Medical Institutions, Baltimore, Maryland, USA.
authors.forename: F A
authors.initials: FA
authors.lastname: Recchia
authors.forename: B J
authors.initials: BJ
authors.lastname: Byrne
authors.forename: D A
authors.initials: DA
authors.lastname: Kass
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000502:physiology; D001809:Blood Viscosity; D002339:Carotid Arteries / Q000502:physiology*; D004548:Elasticity; D004730:Endothelium, Vascular / Q000502:physiology; D066298:In Vitro Techniques; D008297:Male; D011673:Pulsatile Flow / Q000502:physiology*; D013552:Swine; D014664:Vasodilation / Q000502:physiology*