Effects of lipopolysaccharide on tracheal epithelial bioelectric responses to serosally- and mucosally-applied methacholine.
Am J Respir Crit Care Med 1999 Mar; 159(3)(Suppl):A294
We examined whether lipopolysaccharide (LPS) affects transepithelial potential difference V of guinea-pig tracheal epithelium and bioelectric responses to serosally- and mucosally-applied methacholine (MCh). V was measured in vitro using the isolated perfused trachea apparatus, which allows addition of MCh separately to the mucosal or serosal surface. Eighteen hours after LPS (4 mg/kg, Lp.) basal V was increased (saline: -14.9+/- 1.6 mV; LPS: -27.7+/-2.5 mV; p<0.05). In both saline and LPS-treated animals, the dose-response curves for serosally-added MCh were biphasic (hyperpolarization at [MCh] < 10(-6) M; depolarization at [MCh] > 10(-6) M). After LPS-treatment the ECso and maximum response for hyperpolarization were decreased and increased, respectively (p < 0.05), but the EC50 and maximum response for depolarization were not changed. Mucosal MCh was less potent and dose-response curves also were biphasic (hyperpolarization < 10(-3) M; depolarization > 10(-3) M). The maximum hyperpolarization was increased (p<0.05) after LPS-treatment; the depolarization was unaffected. The results suggest that high and low affinity muscarinic receptors initiate changes in V. The mechanism involved in high affinity receptor-induced hyperpolarization is potentiated after LPS-treatment.
Bioelectric-effects; Laboratory-animals; Animals; Animal-studies; In-vitro-studies; Nasal-cavity
Abstract; Conference/Symposia Proceedings
American Journal of Respiratory and Critical Care Medicine