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.
Ideishi
M
M
Department of Internal Medicine, Fukuoka University School of Medicine, Japan.
Miura
S
S
Sakai
T
T
Sasaguri
M
M
Misumi
Y
Y
Arakawa
K
K
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