Ca2+i:K+i ratio and total intracellular calcium in essential and renal hypertension.

The calcium ion (Ca2+) and potassium ion (K+) content in the ashed material from red blood cells was determined by flame photometry in 61 essential hypertensives, 11 renal hypertensives and in 47 normotensive controls, and intracellular K+ concentration was measured in the haemolysate. The ratio between Ca2+ and K+ content in ashed red blood cells (Ca2+i:K+i) was 2.07 +/- 0.91 X 10(-3) in normotensives, 4.91 +/- 2.17 X 10(-3) in essential hypertensives (P less than 0.01) and 3.48 +/- 2.04 X 10(-3) in renal hypertensives (P less than 0.05). Intracellular K+ concentration was 94.3 +/- 3.1 mmol/l in normotensives, 94.7 +/- 3.8 mmol/l in essential hypertensives and 93.8 +/- 3.9 mmol/l in renal hypertensives. Therefore intracellular total Ca2+ concentration is increased in the red blood cells from essential hypertensives and, to a lesser extent, in the red blood cells from renal hypertensives. The use of Ca2+i:K+i ratios in red blood cells may thus be useful in assessing cellular Ca2+ content in hypertension.