1969 年 32 巻 3-4 号 p. 1-24
Up to the present metabolism of silicate in the human body has been scarcely clarified. But in recent years Akiya and Misawa suggested that there might be some relation between the development of arteriosclerosis or hypertension and intake of silicic acid through food and drinking water.
Misawa noticed higher mortality rate of cerebrovascular accidents in the regions with high silicate content in the drinking water. Akiya reported higher silicate deposition in arteriosclerotic arteries than the control.
Therefore, following experiments were performed by the author to study significance of silicate in the cause of hypertension. Daily intake of food and water was kept as constant as possible in quality and quantity during the experiment.
In 32 cases of essential hypertension (I group), 17 cases of healthy adult (II group), and 18 cases of chronic glomerulonephritis or diabetes mellitus (III group) the amounts of daily urinary excretion of meta-silicic acid (M. S.), Na, K, Cl, Po4, Ca, and urine pH were determined for the successive 2 days and compared with each other.
The excretion of M. S. was also studied in relation to the age, systolic blood pressure and serum total cholesterol. In some cases, renal function tests such as GPF, RPF, and PSP were investigated Further, 1-malic acid, 3.0g daily, was administered and the changes in urinary excretion of M. S. were studied in relation to the changes in urinary excretion of electrolytes, urine pH, and renal function. Following results were obtained.
1) Under the above mentioned experimental conditions average excretion of M. S. proved as follows: in the I group: 31.3mg/day (male) and 29.5mg/day (female); in the II group: 31.3mg/day (male) and 30.9mg/day (female): In the III group: 32.7mg/day (male) and 32.3mg/day (female) respectively.
Among these three groups no statistically significant difference was shown. No significant relationship was also observed between the amount of urinary excretion of M. S. and the age, systolic blood pressure, and serum total cholesterol.
Therefore, no definite data suggestive of the causal role of silicic acid in the pathogenesis of hypertension were obtained.
2) A positive correlation was proved between urine pH and urinary excretion of M. S. but the correlation coefficient was 0.3.
3) No significant correlation was observed among the amounts of excreted urinary Na, K, Cl, PO4 Ca, and M. S.
4) Also no constant relationship was proved between GFR, RPF, PSP, concentration capacity, serum non-protein nitrogen and urinary excretion of M. S. However, a slight decrease in the urinary excretion of M. S. was revealed in the renal function impaired group compared with normal function group. But, even in renal function markedly impaired group urinary excretion of M. S. was comparatively well maintained.
5) Although urinary excretion of M. S. was increased significantly by administration of 1-malic acid, the percentage of the cases which showed more than 20% increase was as follows: 59% in the I group, 53% in the II group, and 50% in the III group.
6) As far as the change of urine pH by administration of 1-malic acid is concerned, no constant tendency was confirmed and no particular correlation was seen between the change of urine pH and urinary excretion of M. S., also administration of 1-malic acid induced no significant changes in urinary excretion of Na, K, Cl, Po4, and Ca.
7) Both in the normal and in the renal function impaired groups a significant increase in the urinary excretion of M. S. occurred following the administration of 1-malic acid, however, compared with the normal group a rather weak response was observed in the latter group.