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Comparison of autonomic responses in the trachea isolated from normal and albumin‐sensitive guinea‐pigs
Author(s) -
McCaig Dorothy J.
Publication year - 1987
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1987.tb11385.x
Subject(s) - trachealis muscle , depolarization , stimulation , medicine , vagus nerve , guinea pig , endocrinology , inhibitory postsynaptic potential , chemistry , histamine , parasympathetic nervous system , autonomic nervous system , bronchoconstriction , heart rate , asthma , blood pressure
1 Mechanical and electrical responses to stimulation of the parasympathetic and sympathetic nerves were compared in the trachea isolated from normal guinea‐pigs and from guinea‐pigs sensitized to albumin and exposed repeatedly to inhaled albumin (a model of bronchial asthma). 2 Sensitized trachealis exhibited mechanical hyper‐responsiveness to vagal stimulation characterized by a shift to the left of the frequency‐response relationship and a 71% increase in the maximum response. 3 Transmembrane potential was significantly less negative in sensitized trachealis cells. 4 The amplitude of the depolarization evoked by vagal stimulation (4 or more pulses) was significantly greater in sensitized tissues. Vagally‐mediated depolarization was associated with the appearance of regenerative electrical activity (spikes) in sensitized but not in control tissues. 5 Spontaneous discharge of slow waves occurred in cells from both control and sensitized trachea but the proportion of spontaneously active cells was higher in sensitized tissues. Spontaneous depolarization, like nerve‐mediated depolarization, gave rise to abortive spikes only in sensitized trachealis. 6 Inhibitory responses to stimulation of the sympathetic stellate ganglion, mediated by β‐adrenoceptors, were unaltered in sensitized trachealis. 7 Possible explanations for the hyper‐responsiveness to vagal input in sensitized trachealis are discussed.