Ventilatory response in metabolic acidosis and cerebral blood volume in humans.
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.
Van de Ven
M J
MJ
Department of Pulmonology Dekkerswald, University of Nijmegen, P.O. Box 9001, 6560 GB, Groesbeek, The Netherlands. m.vandeven@long.azn.nl
Colier
W N
WN
van der Sluijs
M C
MC
Oeseburg
B
B
Folgering
H
H
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
D000643:Ammonium Chloride; D002245:Carbon Dioxide