We tested the hypothesis that the
antihypertensive effects of dietary
taurine supplementation in
deoxycorticosterone acetate (
DOCA)-
salt rats may be attributed to the suppression of sympathetic nervous system activity. In uninephrectomized rats treated with
DOCA while receiving 1% NaCl
solution for 2 weeks, systolic blood pressure was significantly increased as compared with that in control rats treated with vehicle
suspension and tap water. Sympathetic nervous system activity was assessed by tissue
norepinephrine turnover, which was determined from the rate of decline of tissue
norepinephrine concentration after the administration of
alpha-methyl-p-tyrosine, a potent inhibitor of the rate-limiting step of
catecholamine synthesis. Cardiac and splenic
norepinephrine turnover during either normal conditions or cold exposure (4 degrees C, 8 hours) were markedly increased in
DOCA-
salt rats as compared with control rats. Also,
DOCA-
salt rats had increased depressor response to
hexamethonium bromide, a
ganglion blocker. In contrast, supplementation of 1%
taurine in
DOCA-
salt rats attenuated the development of the
hypertension associated with the normalization of both the increased depressor response to ganglionic blockade and the accelerated cardiac and splenic
norepinephrine turnover during either normal conditions or cold exposure.
Taurine supplementation in control rats, however, had no effect on blood pressure or
norepinephrine turnover during cold exposure. These results suggest that
taurine supplementation suppresses sympathetic overactivity in
DOCA-
salt rats, thus leading to inhibition of the development of
hypertension.