Upregulation of Arginase Expression and Activity in Hypertensive Rats Exposed to Chronic Intermittent Hypobaric Hypoxia

摘要

Lopez, Vasthi, Patricia Siques, Julio BritCarmen Vallejos, Nelson Naveas, Claudia Carvallo, Fabiola Leo ´n-nVelarde, and Nelson Carvajal. Upregulation of arginase expression and activity in hypertensive rats exposed tonchronic intermittent hypobaric hypoxia. High Alt. Med. Biol. 10:373–381, 2009.— The aim of this study was tonanalyze the activity and expression levels of arginase I and II and to monitor the cardiovascular and hemato-nlogical responses in tolerant and intolerant rats exposed to chronic intermittent hypobaric hypoxia (CIHH). MalenWistar rats (age: 3.0u00010.4 months, weight: 250u000125 g; n¼30) were randomly divided into two groups: CIHH2u00022n(2 days hypoxia, 2 days normoxia, n¼20) and NX (normoxia, n¼10). The hypoxia was simulated in a hypobaricnchamber at 428 torr. Tolerance was determined according to a previous protocol. Arginase activity was measurednin lung and heart tissues, and the expression levels were determined by a (RT-PCR) assay in lung tissue. Resultsnshowed that the intolerants rats had lower body weight, higher hematocrit (Hct) (74u00014% vs. 61u00012%, p<0.05),nhigher values of systolic blood pressure (SBP) (183u00013.7 mmHg vs. 147u00015.4 mmHg, p<0.05), and higher ar-nginase activity. In addition, RT-PCR analysis from lung tissue showed an overexpression of arginase II in thenintolerant group ( p<0.01). However, tolerants had similar values as the NX group ( p¼ns). Further, a correlationnwas found between arginase activity and SBP in the heart (rn2n¼0.596, p<0.001). An upregulation of arginase typenII could be pivotal in understanding the pathogenesis of systolic hypertension and probably other phenomenanassociated with intermittent hypobaric hypoxia. A schematic explanation of these relations is proposed.