Role of electrogenic Na+ pump in the response of sensitized airway smooth muscle to antigen.
Airway smooth muscle (ASM) preparations (mid-cervical portion of trachea) were isolated from control Camm-Hartley male guinea pigs and from animals repeatedly sensitized by ovalbumin. Simultaneously with the measurement of isometric force developed by ASM preparations, resting membrane potential (Em) was determined by employing a conventional microelectrode technique. The contractile and electrophysiological responses of normal and sensitized tissues to ovalbumin and histamine (10(-5) M) were measured during inhibition or stimulation of the electrogenic Na+ pump. The activity of the electrogenic Na+ pump was decreased by the temperature of the experimental bath, i.e., 21 +/- 0.5 degrees C, or by ouabain (10(-5) M). We found that: at 37 degrees C Em of ASM in controls was -60.3 +/- 0.4 mV (+/- SE) as compared to -78.2 +/- 0.4 mV (+/- SE) of ASM from resensitized animals (p less than 0.001); cooling (21 degrees C) decreased (p greater than 0.001) Em of ASM of both controls and resensitized animals; warming (40 degrees C) further increased (p less than 0.01) Em of control ASM but had no effect on Em of ASM from resensitized animals; when the electrogenic Na+ pump was inhibited by low temperature (21 degrees C) or by ouabain (10-5 M), ASM preparations from resensitized animals had no measurable response to ovalbumin; in ASM preparations from controls cooling (21 degrees C) potentiated (p less than 0.01) and warming (40 degrees C) attenuated (p less than 0.01) the histamine (10(-5) M) contractile response; in ASM preparations from resensitized animals, when the electrogenic Na+ pump was inhibited, significant (p less than 0.01) contractile and electrical responses to histamine (10(-5) M) were still present.(ABSTRACT TRUNCATED AT 250 WORDS)
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D000818:Animals; D000941:Antigens / Q000276:immunology*; D004594:Electrophysiology; D006168:Guinea Pigs; D006632:Histamine / Q000276:immunology; D007114:Immunization; D007473:Ion Channels / Q000187:drug effects / Q000502:physiology*; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects / Q000276:immunology*; D010042:Ouabain / Q000494:pharmacology; D010047:Ovalbumin / Q000494:pharmacology; D012964:Sodium / Q000378:metabolism*; D013696:Temperature; D014132:Trachea / Q000187:drug effects / Q000276:immunology*
D000941:Antigens; D007473:Ion Channels; D010042:Ouabain; D006632:Histamine; D010047:Ovalbumin; D012964:Sodium