Influence of gender on oxidative stress, lipid peroxidation, protein damage and apoptosis in hearts and brains from spontaneously hypertensive rats

Abstract

1. Hypertension leads to oxidative stress, lipid and protein damage, apoptosis and impaired cardiac contractile function. However, impact of gender on these hypertension-associated abnormalities has not been elucidated. 2. The present study evaluated the oxidative stress, lipid/protein damage, apoptosis in heart and brain tissues as well as cardiomyocyte contractile function in Wistar Kyoto (WKY) and spontaneously hypertensive rats (SHR) of both genders. Oxidative stress, lipid peroxidation, protein damage and apoptosis were assessed by glutathione (GSH) : reduced glutathione (GSSG) ratio, malondialdehyde (MDA) levels, protein carbonyl levels and caspase-3 activity, respectively. Cardiomyocyte contractile function was examined including peak shortening (PS), time-to-PS (TPS), time-to-90% relengthening (TR90) and maximal velocity of shortening/relengthening (+/-dL/dt). The SHR cardiomyocytes displayed reduced PS and +/-dL/dt compared with gender-matched WKY counterparts. Male but not female SHR cardiomyocytes possessed longer resting cell length, normal TPS and prolonged TR90. All mechanical parameters were comparable between male and female WKY rats with the exception of a higher TR90 in females. Hypertension did not significantly affect the GSH : GSSG ratio in the heart and brain tissues of either gender. Brain from female WKY rats displayed a reduced GSH : GSSG ratio. The MDA levels were unchanged and elevated, respectively, in SHR heart and SHR brain tissues from both genders. Protein carbonyl formation and caspase-3 activity were elevated in male but not female SHR hearts. Nonetheless, brain protein carbonyl level and caspase-3 activity were unaffected by hypertension or gender. 3. In summary, these results suggest that gender affects hypertension-associated oxidative stress, lipid and protein damage, apoptosis in heart and brain tissues and cardiomyocyte contractile function.