Allergen-Induced Bronchoconstriction in Asthmatic Children (4)
To obtain a dose response of BN52021 on the one hand and to avoid tachyphylaxis to PAF on the other hand, PAF challenge was done for four consecutive days, pretreated each day blindly with either placebo or one of the three concentrations of BN52021 (see below), respectively. buy cheap antibiotics
Solutions of methacholine chloride (J.T. Bajer Chemical, Phillips-burg, NJ) were prepared freshly each time. The concentrations of methacholine were 0.075, 0.15, 0.31, 0.62, 1.25, 2.5, 5, 10, and 25 mg/ml. One inhalation unit was defined as one inhalation of methacholine of 1 mg/ml. Solutions of PAF (Sigma, St. Louis, MO) were prepared just before use. The concentrations of PAF were 0, 62.5, 125, 250, 500, 1,000 mg/L, diluted in Hanks’ balanced salt solution (HBSS) containing 0.25 percent human serum albumin. The concentrations of mite extract (Torii, Japan) were 10, 10, 10″\ 10, and 10 (g/ml of HBSS). One inhalation unit of allergen was defined as one inhalation of mite extract of 10 * g/ml. BN52021 (a gift from Dr. Pierre Braquet, IHB, Le Plessis-Robinson, France) was dissolved, according to the manufacturers instruction, in dimethylsulfoxide (DMSO), (Merck, Darmstadt, West Germany) as stock solution (6 x 10′ M) and was diluted in hot HBSS (85 — 90°C) to three concentrations of 450, 150, and 50 ng/ml (1.6 x 10 * M-1.3 x 10′ M).