Journal
HIGH ALTITUDE MEDICINE & BIOLOGY
Volume 10, Issue 4, Pages 373-381Publisher
MARY ANN LIEBERT, INC
DOI: 10.1089/ham.2008.1072
Keywords
intermittent hypoxia; arginase; hypobaria; systemic hypertension; tolerance to high altitude
Funding
- Universidad Arturo Prat
- FONDECYT, Iquique, Chile [2007-11075096]
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Lopez, Vasthi, Patricia Siques, Julio BritCarmen Vallejos, Nelson Naveas, Claudia Carvallo, Fabiola Leon-Velarde, and Nelson Carvajal. Upregulation of arginase expression and activity in hypertensive rats exposed to chronic intermittent hypobaric hypoxia. High Alt. Med. Biol. 10:373-381, 2009.-The aim of this study was to analyze the activity and expression levels of arginase I and II and to monitor the cardiovascular and hematological responses in tolerant and intolerant rats exposed to chronic intermittent hypobaric hypoxia (CIHH). Male Wistar rats (age: 3.0 +/- 0.4 months, weight: 250 +/- 25 g; n = 30) were randomly divided into two groups: CIHH2x2 (2 days hypoxia, 2 days normoxia, n = 20) and NX (normoxia, n = 10). The hypoxia was simulated in a hypobaric chamber at 428 torr. Tolerance was determined according to a previous protocol. Arginase activity was measured in lung and heart tissues, and the expression levels were determined by a (RT-PCR) assay in lung tissue. Results showed that the intolerants rats had lower body weight, higher hematocrit (Hct) (74 +/- 4% vs. 61 +/- 2%, p < 0.05), higher values of systolic blood pressure (SBP) (183 +/- 3.7 mmHg vs. 147 +/- 5.4 mmHg, p < 0.05), and higher arginase activity. In addition, RT-PCR analysis from lung tissue showed an overexpression of arginase II in the intolerant group (p< 0.01). However, tolerants had similar values as the NX group (p = ns). Further, a correlation was found between arginase activity and SBP in the heart (r(2) = 0.596, p < 0.001). An upregulation of arginase type II could be pivotal in understanding the pathogenesis of systolic hypertension and probably other phenomena associated with intermittent hypobaric hypoxia. A schematic explanation of these relations is proposed.
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