Abstract
The thiazide derivatives and the aldosterone antagonists have been used widely as the anti-hypertensive drugs in recent years, though the mechanism by which they lower high blood pressure remains obscure. It can be assumed that the alterations in electrolytes distribution induced by the drugs play an important role in their hypotensive action. However, very limited works have been reported concerning the effect of thiazide derivatives and of the aldosterone antagonists on electrolytes distribution in human subjects and experimental animals. Moreover, among investigators there have been shown a consider able discrepancy of this project. It thus appears to the author that further precise investigation is necessary to determine the electrolytes distribution in plasma and red blood cells after the administration of those drugs in hypertensive subjects. Materials and Methods Fifteen hypertensive subjects without evidence of cardiac or renal failure were selected for the study. Seven patients received I mg of polythiazide twice a day and 8 patients received 50mg of triamterene four times a day for four weeks. Sodium, potassium, chloride and bicarbonate concentrations in plasma, and sodium and potassium concentrations in the red blood cells were determined before and every one week after the treatment for four weeks. The red blood cells were separated by centrifugation at 3, 600g for 30 minutes. Result Serial changes of electrolytes concentration in plasma and red blood cells in the polythia-zide group: Sodium concentration in plasma slightly decreased after the treatment, but its change was not significant. Potassium and chloride concentrations decreased significantly. Bicarbonate concentration rose significantly. Sodium concentration in the red blood cells significantly increased and therefore the ratio of plasma sodium to sodium in the red blood cells, Nae/Nai, significantly decreased. Potassium concentration in the red blood cells had no remarkable change but the ratio of potassium in the red blood cells to plasma potassium, Ki/Ke, significantly increased. These changes were prominent mostly two weeks after the treatment and then returned to the pretreatment levels in the 4th week of treatment. Interestingly there was a close relationship between changes in Nae/Nai or Ki/Ke and bicarbonate concentration.
