Mechanisms of leucocyte sodium influx in essential hypertension

1. Leucocyte Na+ influx in media containing 10 mmol/l Na+ was studied directly using a triple-isotope method for measuring initial 22Na uptake rates in 20 normal and 18 untreated hypertensive subjects. The effects of 1 mmol/l amiloride (a Na+-H+-antiport inhibitor) and 0.1 mmol/l bumetanide (a Na+,K+,Cl-symport inhibitor) were also examined. 2. The total, amiloride-sensitive and bumetanide-sensitive influx rates were raised in hypertensive compared with normotensive subjects [median (range): total 0.63 (0.25-1.82) vs 0.40 (0.09-0.65) mmol min-1 l-1, P less than 0.002; amiloride-sensitive 0.43 (0.18-1.56) vs 0.26 (0.04-0.48) mmol min-1 l-1, P less than 0.002; bumetanide-sensitive 0.12 (-0.03 to 0.83) vs 0.02 (-0.25 to 0.21) mmol min-1 l-1, P less than 0.005]. 3. We conclude that hypertensive patients have a raised leucocyte total Na+ influx when measured in media containing 10 mmol/l Na+ and that this is contributed mainly by amiloride-sensitive and bumetanide-sensitive Na+ influx mechanisms.