[Effect of dietary calcium on erythrocyte sodium pump in spontaneously hypertensive rats (SHR)]

The purpose of the study was to determine the effect of dietary calcium intake on blood pressure and sodium ion transport of red blood cells (RBC) in spontaneously hypertensive rats (SHR). The SHR were fed by diet with three different levels of calcium contents as follows; 0.1% of Ca (low Ca diet), 0.6% of Ca (normal Ca diet) and 4.0% of Ca (high Ca diet) between 6 and 20 weeks of age. At 20 weeks of age, the levels of erythrocyte sodium efflux, as well as sodium and potassium contents in the RBC were measured. On the low calcium diet, SHR showed an enhancement of hypertension. On the high calcium diet, SHR showed an attenuation of the increase in blood pressure. In proportion to the levels of dietary calcium contents, SHR had a lower level of sodium contents in the RBC and a higher activity of the sodium pump. The passive sodium permeability and sodium-potassium cotransport in SHR were similar among low, normal and high calcium diet groups. It is concluded that the amounts of dietary calcium might be related to the regulation of blood pressure by changing the sodium pump of the cell membrane in SHR.