Conclusions
The decreased SBP in the GJ could be due to decreased renin and aldosterone levels in serum and increased urinary volume and excretion of Na+ with its transporter gene alteration. Therefore, ganjang may have antihypertensive effect despite its high contents of salt.
Methods
Sprague-Dawley rats were divided into control (CT), NaCl (NC), and ganjang (GJ) groups and orally administered with 8% NaCl concentration for 9 weeks. The systolic blood pressure (SBP), serum chemistry, Na+ and K+ concentrations and renal gene expressions were measured.
Results
The SBP was significantly increased in the NC group compared to the GJ and CT groups. In addition, the Na+ concentration in urine was higher in the GJ and NC groups than the CT group, but the urine volume was increased in the GJ group compared to the other groups. The serum renin levels were decreased in the GJ group compared to the CT group, while the serum aldosterone level was decreased in the GJ group relative to the NC group. The mRNA expression of the renin, angiotensin II type I receptor, and mineralocorticoid receptor were significantly lower in the GJ group compared to other groups. Furthermore, GJ group showed the lowest levels of genes for Na+ transporter in kidney cortex such as Na+/K+ ATPaseα1 (NKAα1), Na+/H+ exchanger 3 (NHE3), Na+/HCO3- co-exchanger (NBC), and carbonic anhydrases II (CAII). Conclusions: The decreased SBP in the GJ could be due to decreased renin and aldosterone levels in serum and increased urinary volume and excretion of Na+ with its transporter gene alteration. Therefore, ganjang may have antihypertensive effect despite its high contents of salt.