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Chronic antioxidant therapy lowers blood pressure in adult but not in young Dahl salt hypertensive rats: the role of sympathetic nervous system
Author(s) -
Vaněčková I.,
Vokurková M.,
Rauchová H.,
Dobešová Z.,
Pecháňová O.,
Kuneš J.,
Vorlíček J.,
Zicha J.
Publication year - 2013
Publication title -
acta physiologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.591
H-Index - 116
eISSN - 1748-1716
pISSN - 1748-1708
DOI - 10.1111/apha.12092
Subject(s) - medicine , endocrinology , blood pressure , vasodilation , vasoconstriction , oxidative stress , superoxide , aorta , antioxidant , kidney , chemistry , biochemistry , enzyme
Aim It is well‐known that salt hypertension is associated with increased oxidative stress. Since the development of salt hypertension is age‐dependent, we were interested whether young and adult salt hypertensive Dahl rats differ in oxidative stress level and/or in the effects of chronic antioxidant therapy on blood pressure ( BP ) level and on the participation of particular vasoconstrictor/vasodilator systems in BP maintenance. Methods Young (5‐week‐old) and adult (12‐week‐old) salt‐sensitive (Dahl‐S) male rats were fed high‐salt diet (5% NaCl) and drank tempol solution (2 m m ) for 5 weeks. BP was monitored with radiotelemetry and vasoconstrictor/vasodilator balance was evaluated at the end of experiment. Moreover, NO synthase activity, superoxide production and lipoperoxidation were determined in heart, kidney and aorta in separate subgroups of Dahl rats. Results Tempol treatment had quite opposite BP effects in young and adult Dahl‐S rats. While it tended to increase BP in young salt hypertensive Dahl‐S rats, it significantly lowered BP in the adult ones due to reduced sympathetic vasoconstriction. Importantly, high salt intake substantially reduced NO synthase activity in heart and kidney, and markedly increased superoxide production in kidneys and aorta of adult Dahl‐S rats in which BP correlated positively with superoxide production in thoracic aorta and lipoperoxidation in kidneys. Conclusion Chronic antioxidant therapy lowered BP only in adult salt hypertensive Dahl‐S rats in which superoxide levels were increased in both kidneys and aorta. Blood pressure reduction induced by chronic tempol treatment is related to attenuated sympathetic vasoconstriction rather than to augmented NO ‐dependent vasodilatation.