scholarly journals Suppression of the increasing level of acetylcholine-stimulated intracellular Ca2+ in guinea pig airway smooth muscle cells by mabuterol

2015 ◽  
Vol 3 (6) ◽  
pp. 778-786 ◽  
Author(s):  
XIRUI SONG ◽  
CHAO ZHAO ◽  
CAILING DAI ◽  
YANXIN REN ◽  
NAN AN ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Guinea Pig ◽  
Smooth Muscle Cells ◽  
Airway Smooth Muscle ◽  
Muscle Cells ◽  
Airway Smooth Muscle Cells

Substance P activates Cl− and K+ conductances in guinea-pig tracheal smooth muscle cells

1994 ◽  
Vol 72 (6) ◽  
pp. 705-710 ◽  
Author(s):  
Luke J. Janssen ◽  
Stephen M. Sims
Keyword(s):  
Smooth Muscle ◽  
Substance P ◽  
Guinea Pig ◽  
Smooth Muscle Cells ◽  
Voltage Clamp ◽  
Airway Smooth Muscle ◽  
Muscle Cells ◽  
Equilibrium Potential ◽  
Airway Smooth Muscle Cells ◽  
Inward Current

Substance P (SP) causes bronchoconstriction, but its effects on airway smooth muscle ion conductances are unknown. We investigated the effects of SP on single smooth muscle cells dissociated from guinea-pig trachealis. Under voltage clamp at −60 mV, SP evoked reversible contractions and inward current (ISP). ISP had a latency of approximately 1 s, reached a peak of 1039 ± 147 pA (n = 19) about 2 s after onset of application, and declined to baseline levels over the next 5–10 s. At more positive holding potentials (−25 and 0 mV), the inward current was decreased in magnitude and preceded by outward current. With 140 mM K+ in the electrode and Cl− equilibrium potential (ECl) of about 0 mV, ISP was outwardly rectifying and reversed at −11 ± 2 mV. When K+ currents were blocked using Cs+, the current–voltage relationship for ISP was linear and reversed at 3 ± 1 mV. The reversal potential was dependent on the Cl− gradient across the membrane. These results suggest that SP caused a transient activation of Cl− and K+ conductances. Following the initial transient inward current, SP caused a prolonged suppression of spontaneously active K+ currents. The findings that SP evoked contractions during voltage clamp at potentials at which voltage-dependent Ca2+ channels are not active, and that current oscillations were also evoked by SP, suggest that SP is acting through release of Ca2+ from internal stores. Furthermore, SP occluded the inward current evoked by acetylcholine, suggesting that the peptidergic and cholinergic signalling pathways converge. We conclude that SP releases Ca2+ from internal stores in guinea-pig airway smooth muscle cells, leading to activation of Cl− and K+ conductances, depolarization, and contraction.Key words: Ca2+-dependent conductances, spontaneous transient outward currents, acetylcholine.

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