Changes of pathological and physiological indicators affecting drug metabolism in rats after acute exposure to high altitude

High altitude environments cause the human body to undergo a series of pathological, physiological and biochemical changes, which have a certain effect on drug pharmacokinetics. The objective of the present study was to observe changes in factors affecting pharmacokinetics in rats following acute exposure to high altitude and return to low altitude. A total of 21 male Wistar rats were randomly assigned to three groups. The rats in group A were maintained at low altitude in Shanghai, 55 m above sea level; those in group B were acutely exposed to high altitude in Maqu, Gansu, 4,010 m above sea level; and those in group C were acutely exposed to high altitude and then returned to low altitude. Blood was collected from the orbit for the analysis of significant biochemical indicators and from the abdominal aorta for blood gas analysis. Brain, lung and kidney tissues were removed to observe pathological changes. In group B, the pH, buffer base (BB), base excess (BE), total carbon dioxide content (ctCO2), oxygen saturation of arterial blood (sO2), oxygen tension of arterial blood (pO2), serum sodium (Na+) concentration, lactate dehydrogenase (LDH) activity and total protein (TP) level were significantly reduced, and the carbon dioxide tension of arterial blood (pCO2), serum chloride (Cl-) concentration, serum total bilirubin (TBIL) level and alkaline phosphatase (ALP) activity were significantly increased compared with those in group A (P<0.05). In group C, the pH, BB, BE, sO2, pO2, hemoglobin (Hb) level, serum Na+ concentration, LDH activity and TP level were significantly reduced, and the pCO2, serum Cl- concentration, alanine transaminase activity, TBIL and urea levels were significantly increased (P<0.05) compared with those in group A. The Hb and ALP levels in group C were significantly lower than those in group B (P<0.05); and the TP, TBIL and urea levels in group C were significantly higher than those in group B (P<0.05). Pathological observation revealed that the alveolar wall was hyperemic, edematous and incrassate, the alveolar epithelium was hyperplastic and infiltrated with neutrophilic granulocytes and the alveolar septum was widened; brain neurons were edematous with enlarged perivascular spaces, and hippocampal neurons were metamorphic and karyopyknotic; and kidney mesangial cells were hyperplastic, both following acute exposure to high altitude and after returning to low altitude. In conclusion, blood gas indices, biochemical indicators and functions of the heart, liver, kidney were significantly changed, and marked pathological changes occurred in the brain, liver and kidney following acute exposure to high altitude and also after returning to low altitude. These changes are likely to seriously affect the pharmacokinetics of drugs.