title: Sources of calcium for the contraction induced by various agonists in trachealis muscle from normal and sensitized guinea pigs.
abstract: Active sensitization of guinea pigs resulted in an increase in the responsiveness and sensitivity of tracheal strips to CaCl2 in K+-depolarized tissue (Emax 0.81 +/- 0.22 g/mm2 and pD2 2.35 +/- 0.10 in normal vs. 0.98 +/- 0.01 g/mm2 and 3.10 +/- 0.08 in sensitized tissue; p less than 0.05), KCl (Emax 0.62 +/- 0.08 g/mm2 and pD2 1.71 +/- 0.03 in normal vs. 0.91 +/- 0.04 g/mm2 and 2.00 +/- 0.01 in sensitized tissue; p less than 0.05) and histamine (Emax 0.70 +/- 0.06 g/mm2 and pD2 5.08 +/- 0.06 in normal vs. 0.94 +/- 0.09 g/mm2 and 5.80 +/- 0.16 in sensitized tissue; p less than 0.05) but not to caffeine 10 mM (20 degrees C, indomethacin 2.8 microM). Generation of responses to these agonists in nonsensitized tissues bathed in a Ca2+-free medium resulted in the abolition of KCl-induced contraction and partial inhibition of the responses to histamine (60% inhibition) and caffeine (40% inhibition). The contraction of sensitized tracheal strips in response to histamine in 0 calcium was greater than that obtained in nonsensitized tissues (0.48 +/- 0.02 g/mm2 vs. 0.28 +/- 0.04 g/mm2, respectively; p less than 0.05). The caffeine-induced contraction of sensitized tracheae was independent of extracellular calcium. These results suggest that a greater calcium entry and/or intracellular calcium release may be an alteration underlying hyperreactivity of sensitized tissues to spasmogens.
authors.affiliation: Service of Pneumology and Research Center, Hospital ia Fe, Valencia, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Perpiña
authors.forename: M
authors.initials: M
authors.lastname: Palau
authors.forename: J
authors.initials: J
authors.lastname: Cortijo
authors.forename: E
authors.initials: E
authors.lastname: Fornas
authors.forename: J L
authors.initials: JL
authors.lastname: Ortiz
authors.forename: E
authors.initials: E
authors.lastname: Morcillo
mesh_terms: D000818:Animals; D002110:Caffeine / Q000494:pharmacology; D002120:Calcium Channel Agonists / Q000494:pharmacology*; D015220:Calcium Channels / Q000502:physiology*; D002122:Calcium Chloride / Q000494:pharmacology; D003470:Culture Media; D006168:Guinea Pigs; D006632:Histamine / Q000494:pharmacology; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology*; D011189:Potassium Chloride / Q000494:pharmacology; D014132:Trachea / Q000502:physiology*
chemical_list: D002120:Calcium Channel Agonists; D015220:Calcium Channels; D003470:Culture Media; D002110:Caffeine; D011189:Potassium Chloride; D006632:Histamine; D002122:Calcium Chloride