Hypoxia Impairs Endothelial Function in HAPEs

This study has been completed.
Sponsor:
Information provided by:
Heidelberg University
ClinicalTrials.gov Identifier:
NCT00176007
First received: September 10, 2005
Last updated: NA
Last verified: June 2005
History: No changes posted
  Purpose

Aim of the study is to investigate the function of the systemic vascular endothelium in individuals susceptible to high-altitude pulmonary oedema during normoxia and normobaric hypoxia.


Condition Intervention Phase
Healthy
Procedure: Hypoxia
Phase 1

Study Type: Interventional
Study Design: Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Single Blind
Primary Purpose: Educational/Counseling/Training
Official Title: Hypoxia Impairs Systemic Endothelial Function in Individuals Prone to High-Altitude Pulmonary Edema.

Resource links provided by NLM:


Further study details as provided by Heidelberg University:

Detailed Description:

Rationale: High-altitude pulmonary edema (HAPE) is characterized by excessive pulmonary vasoconstriction and is associated with decreased concentrations of nitric oxide (NO) in the lung. Objectives: We hypothesized that individuals susceptible to HAPE (HAPE-S) would also have dysfunction of the vascular NO vasodilator pathway during hypoxia in the systemic vasculature. Methods: During normoxia (FI(O(2)) = 0.21) and 4 hours of normobaric hypoxia (FI(O(2)) = 0.12, corresponding to an altitude of 4,500 m above sea level) endothelium-dependent and endothelium-independent vasodilator responses to intraarterial infusion of acetylcholine (ACh) and sodium nitroprusside, respectively, were measured by forearm venous occlusion plethysmography in nine HAPE-S subjects and in nine HAPE-resistant control subjects. Main Results: Pulmonary artery systolic pressure increased from 22 +/- 3 to 33 +/- 6 mm Hg (p < 0.001) during hypoxia in control subjects, and from 25 +/- 4 to 50 +/- 9 mm Hg in HAPE-S subjects (p < 0.001). Despite similar responses during normoxia in both groups, ACh-induced changes in forearm blood flow markedly decreased during hypoxia in HAPE-S subjects (p = 0.01) but not in control subjects. The attenuated vascular response to ACh infusion during hypoxia inversely correlated with increased pulmonary artery systolic pressure (p = 0.04) and decreased plasma nitrite correlated with attenuated ACh-induced vasodilation in HAPE-S subjects (p = 0.02). Conclusions: Hypoxia markedly impairs vascular endothelial function in the systemic circulation in HAPE-S subjects due to a decreased bioavailability of NO. Impairment of the NO pathway could contribute to the enhanced hypoxic pulmonary vasoconstriction that is central to the pathogenesis of HAPE.

  Eligibility

Ages Eligible for Study:   18 Years to 55 Years
Genders Eligible for Study:   Both
Accepts Healthy Volunteers:   Yes
Criteria

Inclusion Criteria:

Healthy, male volunteers, age: 18-55

- Able and willing to give written informed consent

Exclusion Criteria:

  • Known condition causing endothelial dysfunction (e.g. diabetes, hyperlipidaemia, arterial hypertension, smoking, hyperhomocysteinaemia)
  • Regular medication and/or treatment with drugs within the last 4 weeks (exclusion has to be decided in each case)
  • Acute or chronic illness
  • Participation in clinical trial/blood donation within 2 month before the study
  • Nicotine, drug and/or alcohol abuse.
  Contacts and Locations
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Please refer to this study by its ClinicalTrials.gov identifier: NCT00176007

Sponsors and Collaborators
Heidelberg University
Investigators
Principal Investigator: Walter E Haefeli, MD Heidelberg University
  More Information

No publications provided

ClinicalTrials.gov Identifier: NCT00176007     History of Changes
Other Study ID Numbers: A001
Study First Received: September 10, 2005
Last Updated: September 10, 2005
Health Authority: Germany: Federal Institute for Drugs and Medical Devices

Additional relevant MeSH terms:
Altitude Sickness
Respiration Disorders
Respiratory Tract Diseases

ClinicalTrials.gov processed this record on October 29, 2014