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A comparison of pathophysiological changes during hypobaric and normobaric hypoxia in rats
W Sheedy1, J S Thompson, A H Morice
1Department of Medicine and Pharmacology, University of Sheffield, Royal Hallamshire Hospital, UK.
Respiration; International Review of Thoracic Diseases
|January 1, 1996
Summary
Both normobaric and hypobaric hypoxia cause similar physiological changes in rats, including reduced weight gain and cardiac and vascular alterations. The hypobaric environment did not induce additional stress or changes compared to normobaric hypoxia.
Area of Science:
- Physiology
- Environmental Medicine
- Cardiovascular Research
Background:
- Hypoxia, a condition of reduced oxygen availability, can occur under normobaric (normal pressure) or hypobaric (reduced pressure) conditions.
- Understanding the differential pathophysiological effects of these two types of hypoxia is crucial for managing conditions related to high altitude or respiratory distress.
Purpose of the Study:
- To compare the pathophysiological effects of normobaric hypoxia (NB) versus hypobaric hypoxia (HB) in a rat model.
- To investigate the impact of low oxygen exposure (10% O2) for varying durations (5, 10, and 14 days) on physiological parameters.
Main Methods:
- Male Wistar rats were divided into three groups: normobaric hypoxia (10% O2), hypobaric hypoxia (500 mbar, equivalent to 10% O2), and control.
- Rats were exposed to their respective conditions for 5, 10, or 14 days.
- Parameters measured included body weight, right ventricular hypertrophy, pulmonary arteriole structure (double elastic laminae), hematocrit, and plasma atrial natriuretic peptide (ANP) levels.
Main Results:
- After 5 days, both NB and HB groups showed reduced weight gain, right ventricular hypertrophy, double elastic laminae, increased hematocrit, and elevated plasma ANP compared to controls.
- No significant differences were observed between the NB and HB groups at this time point.
- With prolonged exposure (10 and 14 days), body weight, ventricular ratio, plasma ANP, and double elastic laminae generally increased further in both hypoxic groups, with body weight and hematocrit showing increases from day 10 to day 14.
Conclusions:
- Both normobaric and hypobaric hypoxia at equivalent oxygen concentrations induce similar pathophysiological changes in rats.
- The stress of the hypobaric environment did not lead to additional detrimental effects beyond those caused by normobaric hypoxia.
- These findings suggest that the reduced oxygen partial pressure, rather than the pressure itself, is the primary driver of the observed physiological responses.