Taurine amplifies renal kallikrein and prevents salt-induced hypertension in Dahl rats.
OBJECTIVE
To determine whether taurine reduces blood pressure by stimulating the renal kallikrein-kinin system.


METHODS
The effects of taurine on blood pressure, urinary kallikrein activity and renal kallikrein gene expression were investigated in Dahl salt-sensitive (Dahl-S) rats. The specificity of the action of taurine was verified by comparison with the action of beta-alanine, a carboxylic analogue of taurine. The effect of co-administration of the specific bradykinin B2 receptor antagonist Hoe 140 was also examined.


RESULTS
Administration of taurine (3% in drinking water) for 4 weeks retarded the development of salt (4% sodium chloride diet)-induced hypertension. Systolic blood pressure at the end of the experiment was significantly higher in control rats than in taurine-treated rats. Urinary sodium excretion was not decreased by the reduction in blood pressure. The heart weight:body weight ratio was significantly lower, and urinary volume and kallikrein excretion were significantly higher, in taurine-treated rats. Renal kallikrein gene expression at weeks 1 and 4 was higher in taurine-treated rats. Systolic blood pressure 3 and 4 weeks after the administration of beta-alanine was slightly, but not significantly, lower than that of untreated rats on a high-salt diet, and was accompanied by a significantly lower body weight. Urinary kallikrein excretion decreased with a high-salt diet regardless of beta-alanine administration. Continuous systemic administration of Hoe 140 did not cause any significant alteration in blood pressure in Dahl-S rats that received taurine with a high-salt diet. Taurine also showed a renoprotective effect, as judged by a reduction in proteinuria.


CONCLUSIONS
These results suggest that taurine is an effective antihypertensive agent for salt-induced hypertension. Although taurine activated renal kallikrein, further studies are required to confirm the participation of activated kallikrein in the antihypertensive, cardioprotective and renoprotective effects of taurine.
Department of Internal Medicine, Fukuoka University School of Medicine, Japan.
M
M
Ideishi
S
S
Miura
T
T
Sakai
M
M
Sasaguri
Y
Y
Misumi
K
K
Arakawa
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D001920:Bradykinin / Q000031:analogs & derivatives / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects; D006973:Hypertension / Q000517:prevention & control*; D007610:Kallikreins / Q000096:biosynthesis / Q000235:genetics / Q000652:urine*; D007668:Kidney / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D012965:Sodium Chloride / Q000494:pharmacology*; D013654:Taurine / Q000494:pharmacology*; D015091:beta-Alanine / Q000494:pharmacology
D015091:beta-Alanine; D013654:Taurine; D012965:Sodium Chloride; C065679:icatibant; D007610:Kallikreins; D001920:Bradykinin