title: Beta blockade increases pulmonary and systemic transit time heterogeneity: evaluation based on indocyanine green kinetics in healthy volunteers.
abstract: Knowledge of factors influencing the heterogeneity of blood transit times is important in cardiovascular physiology. The aim of the study was to investigate the effect of beta-adrenergic blockade on blood transit time dispersion in awake, anxious volunteers. Recirculatory modelling of the disposition of intravascular markers using parametric forms for transit time distributions, such as the inverse Gaussian distribution, provides the opportunity to estimate the systemic and pulmonary transit time dispersion in vivo. The latter is determined by the flow heterogeneity in the microcirculatory network. Using this approach, we have analysed indocyanine green (ICG) disposition data obtained in four subjects by frequent early arterial blood sampling before and after beta-adrenergic blockade by propranolol. Propranolol decreased cardiac output from 9·3 ± 2·8 l min-1to 3·5 ± 0·47 l min-1(P<0·05). This reduction was accompanied by a 4·5 ± 0·6-fold and 2·1 ± 0·3-fold increase (P<0·001) in the relative dispersion (dimensionless variance) of blood transit times through the systemic and pulmonary circulation, respectively.
authors: Department of Pharmacology, Martin Luther University Halle-Wittenberg, Halle, Germany.
authors: Michael
authors: M
authors: Weiss
authors: Department of Anesthesiology and the Mary Beth Donnelley Clinical Pharmacology Core Facility, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA.
authors: Tom C
authors: TC
authors: Krejcie
authors: Department of Anesthesiology and the Mary Beth Donnelley Clinical Pharmacology Core Facility, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA.
authors: Michael J
authors: MJ
authors: Avram
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D001783:Blood Flow Velocity / Q000187:drug effects; D002302:Cardiac Output / Q000187:drug effects; D002851:Chromatography, High Pressure Liquid; D003198:Computer Simulation; D005456:Fluorescent Dyes / Q000008:administration & dosage / Q000493:pharmacokinetics*; D064368:Healthy Volunteers; D006801:Humans; D007208:Indocyanine Green / Q000008:administration & dosage / Q000493:pharmacokinetics*; D008297:Male; D008833:Microcirculation / Q000187:drug effects; D008955:Models, Cardiovascular; D011433:Propranolol / Q000494:pharmacology*; D011652:Pulmonary Circulation / Q000187:drug effects*
chemical_list: D000319:Adrenergic beta-Antagonists; D005456:Fluorescent Dyes; D011433:Propranolol; D007208:Indocyanine Green
keywords: cardiac output; flow heterogeneity; propranolol; recirculatory model; transit time distribution