title: Ventilatory response in metabolic acidosis and cerebral blood volume in humans.
abstract: The relationship between alterations in cerebral blood volume (CBV) and central chemosensitivity regulation was studied under neutral metabolic conditions and during metabolic acidosis. Fifteen healthy subjects (56+/-10 years) were investigated. To induce metabolic acidosis, ammonium chloride (NH(4)Cl) was given orally. CBV was measured using Near Infrared Spectroscopy during normo- and hypercapnia and related to inspired ventilation (V(i)). A mean acute metabolic acidosis of Delta pH - 0.04 was realized with a mean decreased arterialized capillary PCO(2) (P(c)CO(2)) of 0.20 kPa (1.5 mmHg) (both P<0.001). During normocapnia, CBV was 3.51+/-0.71 and 3.65+/-0.56 ml 100 g(-1) (mean+/-S.D.), measured under neutral metabolic conditions and during acute metabolic acidosis, respectively (ns). Corresponding values of V(i) were 7.6+/-1.4 and 10.0+/-2.4 l min(-1) (P<0.01), respectively. The slopes of the CO(2)-responsiveness (DeltaCBV/DeltaP(c)CO(2) and DeltaV(i)/DeltaP(c)CO(2)), were not significantly different during both metabolic conditions. A significant correlation between DeltaCBV/DeltaP(c)CO(2) and DeltaV(i)/DeltaP(c)CO(2) was found during metabolic acidosis (P<0.01), but not under neutral metabolic conditions. CBV does not contribute in a predictable way to the regulation of central chemoreceptors.
authors.affiliation: Department of Pulmonology Dekkerswald, University of Nijmegen, P.O. Box 9001, 6560 GB, Groesbeek, The Netherlands. m.vandeven@long.azn.nl
authors.forename: M J
authors.initials: MJ
authors.lastname: Van de Ven
authors.forename: W N
authors.initials: WN
authors.lastname: Colier
authors.forename: M C
authors.initials: MC
authors.lastname: van der Sluijs
authors.forename: B
authors.initials: B
authors.lastname: Oeseburg
authors.forename: H
authors.initials: H
authors.lastname: Folgering
mesh_terms: D000138:Acidosis / Q000139:chemically induced / Q000503:physiopathology*; D000368:Aged; D000643:Ammonium Chloride / Q000008:administration & dosage / Q000494:pharmacology; D001794:Blood Pressure; D001921:Brain / Q000098:blood supply*; D002245:Carbon Dioxide / Q000097:blood; D002628:Chemoreceptor Cells / Q000378:metabolism; D005260:Female; D006801:Humans; D006935:Hypercapnia / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D012123:Pulmonary Ventilation / Q000187:drug effects / Q000502:physiology*; D012044:Regression Analysis; D019265:Spectroscopy, Near-Infrared / Q000295:instrumentation / Q000379:methods
chemical_list: D000643:Ammonium Chloride; D002245:Carbon Dioxide