title: Nitric oxide influences red blood cell velocity independently of changes in the vascular tone.
abstract: Nitric oxide (NO) plays a key role in regulation of vascular tone and blood flow. In the microcirculation blood flow is strongly dependent on red blood cells (RBC) deformability. In vitro NO increases RBC deformability. This study hypothesized that NO increases RBC velocity in vivo not only by regulating vascular tone, but also by modifying RBC deformability. The effects of NO on RBC velocity were analysed by intra-vital microscopy in the microcirculation of the chorioallantoic membrane (CAM) of the avian embryo at day 7 post-fertilization, when all vessels lack smooth muscle cells and vascular tone is not affected by NO. It was found that inhibition of enzymatic NO synthesis and NO scavenging decreased intracellular NO levels and avian RBC deformability in vitro. Injection of a NO synthase-inhibitor or a NO scavenger into the microcirculation of the CAM decreased capillary RBC velocity and deformation, while the diameter of the vessels remained constant. The results indicate that scavenging of NO and inhibition of NO synthesis decrease RBC velocity not only by regulating vascular tone but also by decreasing RBC deformability.
authors.affiliation: Division of Cardiology, Pneumology and Angiology, Medical Faculty of the Heinrich Heine University of Duesseldorf, Germany.
authors.forename: Patrick
authors.initials: P
authors.lastname: Horn
authors.forename: Miriam M
authors.initials: MM
authors.lastname: Cortese-Krott
authors.forename: Stefanie
authors.initials: S
authors.lastname: Keymel
authors.forename: Intan
authors.initials: I
authors.lastname: Kumara
authors.forename: Sandra
authors.initials: S
authors.lastname: Burghoff
authors.forename: Jürgen
authors.initials: J
authors.lastname: Schrader
authors.forename: Malte
authors.initials: M
authors.lastname: Kelm
authors.forename: Petra
authors.initials: P
authors.lastname: Kleinbongard
mesh_terms: D000818:Animals; D048430:Cell Shape / Q000187:drug effects; D002642:Chick Embryo; D002645:Chickens; D049033:Chorioallantoic Membrane / Q000098:blood supply / Q000187:drug effects; D004912:Erythrocytes / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D006439:Hemodynamics / Q000187:drug effects*; D066298:In Vitro Techniques; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D009952:Ornithine / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: D009569:Nitric Oxide; C065027:N(G)-iminoethylornithine; D009952:Ornithine; D019001:Nitric Oxide Synthase