title: Ascending aorta input impedance during hemorrhagic shock and after hyperosmotic solution infusion.
abstract: Aortic input impedance was determined in four dogs anesthetized with chloralose-urethane. Flow and pressure were recorded in the ascending aorta during random heart pacing. Signals were processed on a HP 3882A spectrum analyzer utilizing the Fast Fourier Transform. Measurements were made under control conditions, during hemorrhagic shock, and after infusion of a hyperosmotic solution (HS). Results show that HS decreases peripheral resistance, input impedance, frequency of minimal input impedance, and frequency of zero degree phase crossing. The last two indicate a slower pressure wave velocity. These data, together with a reduction in characteristic impedance, strongly suggest a decrease in arterial vascular tonus.
authors.affiliation: Instituto de Biofisica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Brasil.
authors.forename: A C
authors.initials: AC
authors.lastname: Garcia
authors.forename: A F
authors.initials: AF
authors.lastname: Costa
mesh_terms: D000818:Animals; D001011:Aorta / Q000503:physiopathology*; D001775:Blood Circulation; D001794:Blood Pressure; D004285:Dogs; D008433:Mathematics; D012462:Saline Solution, Hypertonic / Q000008:administration & dosage*; D012771:Shock, Hemorrhagic / Q000503:physiopathology*; D012965:Sodium Chloride / Q000008:administration & dosage*
chemical_list: D012462:Saline Solution, Hypertonic; D012965:Sodium Chloride