title: Lower hypoxic ventilatory response in smokers compared to non-smokers during abstinence from cigarettes.
abstract: Carotid body O2-chemosensitivity determines the hypoxic ventilatory response (HVR) as part of crucial regulatory reflex within oxygen homeostasis. Nicotine has been suggested to attenuate HVR in neonates of smoking mothers. However, whether smoking affects HVR in adulthood has remained unclear and probably blurred by acute ventilatory stimulation through cigarette smoke. We hypothesized that HVR is substantially reduced in smokers when studied after an overnight abstinence from cigarettes i.e. after nicotine elimination.
  
  
  
  We therefore determined the isocapnic HVR of 23 healthy male smokers (age 33.9 ± 2.0 years, BMI 24.2 ± 0.5 kg m-2, mean ± SEM) with a smoking history of >8 years after 12 h of abstinence and compared it to that of 23 healthy male non-smokers matched for age and BMI.
  
  
  
  Smokers and non-smokers were comparable with regard to factors known to affect isocapnic HVR such as plasma levels of glucose and thiols as well as intracellular levels of glutathione in blood mononuclear cells. As a new finding, abstinent smokers had a significantly lower isocapnic HVR (0.024 ± 0.002 vs. 0.037 ± 0.003 l min-1%-1BMI-1, P = 0.002) compared to non-smokers. However, upon re-exposure to cigarettes the smokers' HVR increased immediately to the non-smokers' level.
  
  
  
  This is the first report of a substantial HVR reduction in abstinent adult smokers which appears to be masked by daily smoking routine and may therefore have been previously overlooked. A low HVR may be suggested as a novel link between smoking and aggravated hypoxemia during sleep especially in relevant clinical conditions such as COPD.
authors.affiliation: Former Department of Immunochemistry, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 60120, Heidelberg, Germany. wulf.hildebrandt@staff.uni-marburg.de.|Department of Medical Cell Biology, Institute of Anatomy and Cell Biology, University of Marburg, Robert-Koch-Straße 8, D-35032, Marburg, Germany. wulf.hildebrandt@staff.uni-marburg.de.
authors.forename: Wulf
authors.initials: W
authors.lastname: Hildebrandt
authors.affiliation: Former Department of Immunochemistry, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 60120, Heidelberg, Germany.|Department of Neurology, University Hospital Erlangen, Schwabachanlage 6, 91054, Erlangen, Germany.
authors.forename: Roland
authors.initials: R
authors.lastname: Sauer
authors.affiliation: Sleep Disorder Unit, Department of Pneumology, University Hospital Marburg, Baldingerstraße, 35043, Marburg, Germany.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Koehler
authors.affiliation: Division VII (Sports Medicine), Medical University Clinic, University of Heidelberg, Im Neuenheimer Feld 410, D-69120, Heidelberg, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Bärtsch
authors.affiliation: Department of Medical Cell Biology, Institute of Anatomy and Cell Biology, University of Marburg, Robert-Koch-Straße 8, D-35032, Marburg, Germany.
authors.forename: Ralf
authors.initials: R
authors.lastname: Kinscherf
mesh_terms: D000328:Adult; D002344:Carotid Body / Q000098:blood supply; D003430:Cross-Sectional Studies; D005858:Germany; D005978:Glutathione / Q000378:metabolism; D064368:Healthy Volunteers; D006706:Homeostasis; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology*; D008297:Male; D015999:Multivariate Analysis; D010100:Oxygen / Q000097:blood*; D012123:Pulmonary Ventilation; D012044:Regression Analysis; D012119:Respiration; D012907:Smoking / Q000009:adverse effects* / Q000097:blood; D013438:Sulfhydryl Compounds / Q000097:blood; D013997:Time Factors
chemical_list: D013438:Sulfhydryl Compounds; D005978:Glutathione; D010100:Oxygen
keywords: Carotid body; Chemoreceptor; Nicotine; O2-sensing; Smoking; Ventilation