Intracellular calcium and sodium in hypertensive patients.

Abstract

Untreated subjects with mild to moderate hypertension were compared with normotensive controls recruited from the same ambulatory screening clinic. All subjects were black. Resting levels of cytosolic free calcium were estimated in washed platelets with the fluorescent intracellular probe fura 2, and sodium and potassium were measured in red blood cells. Calcium levels were 21% higher in the hypertensive subjects (p = 0.02), and a 9% increase in sodium was observed in an expanded sample (p = 0.04). Neither intracellular calcium nor intracellular sodium had a significant linear correlation with blood pressure when hypertensive subjects and controls were examined separately or when the two groups were combined. Potassium was slightly but not significantly increased in hypertensive subjects. Among the participants for whom both calcium and sodium measurements were available, a weak, nonsignificant correlation between these ions was noted (r = 0.2; n = 48). This correlation was significant among participants in the control group examined separately (r = 0.3; n = 33; p = 0.05). Although the measurements were performed in different cell lines, these findings demonstrate increases in both intracellular calcium and sodium in hypertensive humans.