Upregulation of arginase expression and activity in hypertensive rats exposed to chronic intermittent hypobaric hypoxia.
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: CIHH2 x 2 (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.
Lopez
Vasthi
V
Instituto de Estudios de la Salud, Universidad Arturo Prat, Iquique, Chile. vasthi.lopez@unap.cl
Siques
Patricia
P
Brito
Julio
J
Vallejos
Carmen
C
Naveas
Nelson
N
Carvallo
Claudia
C
León-Velarde
Fabiola
F
Carvajal
Nelson
N
D000064:Acclimatization; D000531:Altitude; D000818:Animals; D001119:Arginase / Q000378:metabolism*; D001274:Atmospheric Pressure; D001794:Blood Pressure; D001835:Body Weight; D006339:Heart Rate; D006400:Hematocrit; D006973:Hypertension / Q000150:complications / Q000378:metabolism* / Q000503:physiopathology; D000860:Hypoxia / Q000150:complications / Q000378:metabolism*; D008168:Lung / Q000378:metabolism; D008297:Male; D009206:Myocardium / Q000378:metabolism; D009566:Nitrates / Q000097:blood; D009573:Nitrites / Q000097:blood; D051381:Rats; D017208:Rats, Wistar; D015854:Up-Regulation
D009566:Nitrates; D009573:Nitrites; D001119:Arginase