Effect of Salt Intake on Blood Pressure and Urinary Kallikrein Excretion in Spontaneously Hypertentive Rats and Rats of Wistar Kyoto Strain

Abstract

Five weeks old male spontaneously hypertensive rats (SHR) and male Wistar Kyoto rats (WKy) were fed with CE-2 food and three kinds of drink ad libitum for 14 weeks. The SHR and WKy were each divided into two groups according to kind of drink, water (W group) and 1% saline solution (S group). In addition to the above four groups, another group of SHR was given 0.5% NaCl and 0.5% KCI solution (K group) for the purpose of studying the effects of potassium on blood pressure and urinary kallikrein excretian.
Results obtained were as follows; In both SHR and WKy, the mean value of blood pressure for the S group was higher than that for the W group. However, the ratio of rise in blood pressure in the S group to that in the W group was considerably greater in SHR than in WKy. In SHR, the elevated blood pressure for the K group was lower than that for the S group. fihus, this experiment indicated that the hypertensive effect of salt was greater in SHR than in WKy. In the SHR, drinking volume was much greater in the S group than in the W group. These results suggest that the SHR showed stronger salt appetite and thirst than the WKy when 1% saline solution was provided. A strong appetite for salt could be one of the factors elevating blood pressure by increasing extracellular fluid. In both strains, blood pressure became higher and urinary kallikrein excretion increased as the rats grew. However, excretion af urinary kallikrein was not so increased in SHR as expected in view of their high blood pressure. Since urinary kallikrein has diuretic and natriuretic effects in addition to a hypotensive effect, disturbance of urinary kallikrein excretion in SHR may be one of the causes which raise blood pressure in SHR.