Heart and liver mitochondrial nitric oxide synthase in male rats exposed acutely to high altitude (4340 m)

GONZALES GF; CHUNG FA; MIRANDA S; VALDEZ LB; ZAOBORNYJ T; BOVERIS A

Am J Physiol Heart Circ Physiol

Año: 2005 vol. 288 p. 2568 - 2573

Male rats exposed for 21 days to high altitude (4340 m) responded with arrest of gain weight and increased hematocrit and testosterone levels. High altitude significantly (58%) increased heart mitochondrial nitric oxide synthase (mtNOS) activity, whereas heart cytosolic eNOS and liver mtNOS were not affected. Western blot analysis found heart mitochondria reacting only with anti-iNOS antibodies, whereas the post mitochondrial fraction reacted with anti-iNOs and anti-eNOS antibodies. In vitro measured NOS activities allowed the estimation of cardiomyocite capacity for NO production, a value that increased from 57 (sea level) to 79 nmol NO/min.g heart (4340 m). The contribution of mtNOS to total cell NO production increased from 62 % (sea level) to 71 % (4340 m). Heart mtNOS activity showed a linear relationship with hematocrit and a biphasic quadratic association with estradiol and testosterone. Multivariate analysis showed that exposure to high altitude linearly associates with hematocrit and heart mtNOS activity, and that testosterone/estradiol ratio and heart weight were not linearly associated with mtNOS activity. We conclude that high altitude triggers a physiological adaptive response that up-regulates heart mtNOS activity and is associated, in an opposed manner, with the serum levels of testosterone and estradiol.