title: Effect of immune sensitization on stimulated ACh release from trachealis muscle in vitro.
abstract: We assessed the effect of immune sensitization on acetylcholine (ACh) release from parasympathetic nerve terminals in tracheal smooth muscle (TSM) strips from ragweed-sensitized (RWS) and sham-sensitized, littermate control (LMC) dogs. Strips of TSM were tethered to force transducers at optimal length in perfusion chambers containing [3H]choline and a fixed volume of physiological perfusate. Tissues were equilibrated for 1 h by electrical field stimulation (EFS) every 5 min to facilitate uptake of label into parasympathetic nerves as ACh. Fresh perfusate (containing 3 x 10(-8) M physostigmine) was collected at 5-min intervals for 1 h, and a rate coefficient of [3H]ACh release was determined. Tissues were exposed to agonists in the seventh collection period, and the increase in label release (ratio change where < or = 1.00 = baseline) and force production were determined. Ragweed antigen challenge stimulated [3H]ACh release and contraction in RWS but not LMC tissues. [3H]ACh release was 1.93 +/- 0.22 x baseline in RWS vs. 0.92 +/- 0.02 in control tissues (P < 0.01); contraction was 31.2 +/- 9.5% of that elicited by EFS (% EFS) in RWS vs. 0% EFS in LMC tissues (P < 0.01). Strips of TSM from RWS but not LMC dogs demonstrated concentration-dependent, augmented release of ACh caused by histamine. After 10(-4) M histamine, [3H]ACh release in RWS was 1.94 +/- 0.37 x baseline vs. 1.05 +/- 0.06 for LMC tissues (P < 0.05); histamine also caused greater contraction in RWS (106.5 +/- 5.9% EFS) vs. LMC (86.5 +/- 5.6% EFS; P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Medicine, University of Chicago, Illinois 60637.
authors.forename: R W
authors.initials: RW
authors.lastname: Mitchell
authors.forename: I M
authors.initials: IM
authors.lastname: Ndukuw
authors.forename: K
authors.initials: K
authors.lastname: Ikeda
authors.forename: K
authors.initials: K
authors.lastname: Arbetter
authors.forename: A R
authors.initials: AR
authors.lastname: Leff
mesh_terms: D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D000941:Antigens / Q000276:immunology; D004285:Dogs; D004558:Electric Stimulation; D006632:Histamine / Q000494:pharmacology; D007114:Immunization; D009130:Muscle, Smooth / Q000276:immunology / Q000378:metabolism*; D009994:Osmolar Concentration; D014677:Pharmaceutical Vehicles; D011058:Pollen / Q000276:immunology; D013268:Stimulation, Chemical; D014132:Trachea / Q000276:immunology / Q000378:metabolism*
chemical_list: D000941:Antigens; D014677:Pharmaceutical Vehicles; D006632:Histamine; D000109:Acetylcholine