Effect of hypertensive plasma on Ca2+ transport in human neutrophils

The effects of plasma fractions from essential hypertensives (n = 17) and normotensives (n = 17) on Ca2+ transport in permeabilised human neutrophils were studied using an ion-selective electrode. The plasma fractions were obtained by gel filtration and contained substances with a molecular weight in the range of 1000-1500 Da. When isolated from essential hypertensives, this fraction had been shown to increase blood pressure after intravenous injection in the rat. The rate of Ca2+ uptake by permeabilised neutrophils after addition of extracellular Ca2+ was significantly accelerated during incubation of the cells with the hypertensive fraction (855.9 +/- 812.3% vs 218.0 +/- 294.3% of the control value, P less than 0.05). In a suspension with intact neutrophils hypertensive plasma fractions (n = 7) caused an increase of extracellular pCa by 0.479 +/- 0.115 (P less than 0.01), whereas the normotensive fractions did not change pCa significantly. It is concluded that the hypertensive plasma fraction increases Ca2+ accumulation in subcellular particles. Additionally the Ca2+ influx through the plasma membrane is increased by the circulating hypertensive factor.