The effect ofl-glutamic acid on airway function and reactivity in the rabbit
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The ingestion of monosodium glutamate in sensitive individuals has been reported to cause severe asthma. We therefore studied the effects ofl-glu on airway function and histamine (H) responsiveness in the rabbit. Histamine dose response curves (HDR's) were performed by measuring total lung resistance (RL) after inhalation of saline and increasing concentrations of H (1–30 mg/ml). The concentration of H producing a 20% increase in RL (PC20H) was obtained by interpolation. To assess the effects ofl-glu, 8 rabbits were infused withl-glu (0.2 g/kg/hr) or saline in random order (14 days apart) for 4 hours followed by an HDRC. To look at possible late effects, a repeat HDRC was also performed in 6 rabbits 12 hours after completion of thel-glu infusion. In order to see whether rabbits rendered hyperresponsive responded tol-glu, the above protocol was performed in 7 rabbits following the inhalation of 3 μg of the activated complement fragment C5a des Arg. Thel-glu infusions increased the plasma levels approx. ten-fold (mean±SEM 0.119±0.012 base-line, 1.272±0.061 mmol/l post infusion).l-glu did not increase the PC20H or baseline RL in either the normal rabbits at 4 or 12 hours or in the C5a des Arg treated rabbits at 4 hours.
It is concluded thatl-glu does not cause bronchoconstriction or an increase in airway responsiveness to H in the rabbit.
KeywordsAsthma Glutamate Histamine Dose Response Dose Response Curve
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