Passive sensitization of human bronchi augments smooth muscle shortening velocity and capacity
Mitchell, R.W.; Rühlmann, E.; Magnussen, H.; Leff, A.R.; Rabe, K.F.
American Journal of Physiology 267(2 Pt 1): L218-L222
1994
ISSN/ISBN: 0002-9513 PMID: 8074246 Document Number: 435282
We assessed whether incubation with human serum from atopic individuals containing high concentrations of immunoglobuhn E (IgE) causes augmentation of maximal contraction of human bronchial smooth muscle from nonatopic subjects in vitro. Bronchi were obtained from eight patients undergoing lung resection, and force-velocity relationships were determined for eight pairs of epithelium-intact bronchial rings of generations 6-7 using an electromagnetic lever system, which allowed isotonic shortening when load clamps (from 0 to maximal isometric force (P-o)) were applied at specific times after onset of contraction. Contractions were elicited by supramaximal electrical field stimulation (50 Hz, 10 s train duration, 25 V). Optimal length (L-o) for each tissue was determined during equilibration. After resection, tissues were sensitized passively with human sera containing high titers ( gt 1,000 U/ml) of IgE by incubation for 16 h at 20 degree C. Maximal shortening velocity (V-max) was increased for passively sensitized bronchi (0.1150 +- 0.0240 1/2 circumferences/s (1/2Cir/s)) compared with sham-sensitized bronchi (0.0731 +- 0.0152 1/2Cir/s, P = 0.038). Similarly, maximal shortening (DELTA-L-max) was augmented in sensitized bronchial rings (11.27 +- 1.80 %L-o) compared with sham-sensitized tissues (8.19 +- 1.39 %L-o, P = 0.012). However, P-o did not differ between sensitized (122.5 +- 24.4 mN/cm-2) compared with sham-sensitized tissues (138.4 +- 32.1 mN/cm-2, P = 0.642). Our data are the first demonstration that V-max and DELTA-L-max are augmented in sensitized but not challenged human bronchial rings after passive sensitization using human serum containing high concentrations of IgE.