Am. J. Respir. Crit. Care Med., Vol 149, No. 6, Jun 1994, 1426-1433.
Dietary sodium intake, airway responsiveness, and cellular sodium transport
RM Tribe, JR Barton, L Poston and PG Burney
Department of Public Health Medicine and Renal Laboratory, United Medical School, Guy's Hospital, London, United Kingdom.
Both epidemiologic and experimental evidence suggest that a high dietary
sodium intake may increase airway responsiveness, but no adequate
explanation exists of how changes in sodium intake might lead to increased
responsiveness. This investigation was carried out to study dietary sodium
intake and airway response to methacholine in relation to cellular sodium
transport in 52 young men. Airway response to methacholine was associated
with urinary sodium excretion when subjects were on normal sodium intake.
Airway responsiveness in patients with mild asthma correlated with the
furosemide-insensitive influx of sodium into peripheral leukocytes
stimulated by autologous serum, but there was no relation between this
influx and 24-h urinary sodium excretion. In a separate investigation,
serum from subjects with increased airway responsiveness caused an increase
in the sodium influx and sodium content of leukocytes from nonatopic
subjects. The magnitude of the furosemide-insensitive, serum stimulated
influx was related to the degree of airway responsiveness of the serum
donor, as was the increase in intracellular sodium content. Neither was
related to the 24- h urinary sodium excretion of the donor. Patients with
airway hyperresponsiveness have an increased sodium influx into cells
stimulated by a serum-borne factor. This is independent of the effect of
added dietary sodium on airway responsiveness.
