PMID: 8967511May 1, 1996Paper

Acetylcholine and caffeine activate Cl- and suppress K+ conductances in human bronchial smooth muscle

The American Journal of Physiology
L J Janssen

Abstract

The conductance changes underlying agonist-evoked depolarization in human airway smooth muscle (ASM) were examined using single ASM cells liberated enzymatically from noncarcinomatous bronchi and studied using patch-clamp techniques. Step commands to potentials at or more positive than the resting membrane potential evoked outward current, which was predominantly delayed rectifier K+ current with some Ca(2+)-dependent K+ current Caffeine (5 mM) evoked depolarization and contraction lasting several minutes. During voltage clamp at -60 mV, caffeine evoked inward current with a latency of approximately equal to 1 s, mean amplitude of 320 +/- 65 pA, and a duration of approximately equal to 5 s (even though agonist application exceeded this duration). With the use of the perforated-path configuration, these responses could be evoked repeatedly at 4-min intervals for up to 30 min; rupture of the membrane and dialysis of the cytosol, however, abrogated the responses to caffeine. The current was outwardly rectifying with mean reversal potential (Vrev) of -31 +/- 4 mV. When K+ conductances were blocked by Ca+, the current-voltage (I-V) relationship was linear (i.e., an outwardly-rectifying component was eliminated) and Vrev was displace...Continue Reading

Citations

Apr 27, 2000·American Journal of Physiology. Lung Cellular and Molecular Physiology·L J JanssenS Keshavjee
May 11, 2002·American Journal of Physiology. Lung Cellular and Molecular Physiology·Luke J Janssen
Sep 8, 2010·Experimental Physiology·Steven E S MinerJohn D Parker
Jan 24, 2006·American Journal of Physiology. Lung Cellular and Molecular Physiology·Simon HirotaLuke J Janssen
Feb 22, 2012·American Journal of Physiology. Lung Cellular and Molecular Physiology·Luke J Janssen
Jun 1, 2014·American Journal of Physiology. Lung Cellular and Molecular Physiology·Jennifer DanielssonCharles W Emala
May 11, 2002·American Journal of Physiology. Lung Cellular and Molecular Physiology·Q J Li, L J Janssen

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