Secondhand smoke exposure alters K plus channel function and intrinsic cell excitability in a subset of second-order airway neurons in the nucleus tractus solitarius of young guinea pigs

作者：Sekizawa Shin ichi^*; Joad Jesse P; Pinkerton Kent E; Bonham Ann C

来源：European Journal of Neuroscience, 2010, 31(4): 673-684.

DOI：10.1111/j.1460-9568.2010.07093.x

• airway afferent fibers
• environmental air pollutants
• intrinsic cell excitability
• ion channels
• K plus currents
• postsynaptic neurons

Extended exposure to secondhand smoke (SHS) in infants and young children increases the incidence of cough, wheeze, airway hyper-reactivity and the prevalence and earlier onset of asthma. The adverse effects may result from environmentally-induced plasticity in the neural network regulating cough and airway function. Using whole-cell patch-clamp recordings in brainstem slices containing anatomically identified second-order lung afferent neurons in the nucleus tractus solitarius (NTS), we determined the effects of extended SHS exposure in young guinea pigs for a duration equivalent to human childhood on the intrinsic excitability of NTS neurons. SHS exposure resulted in marked decreases in the intrinsic excitability of a subset of lung afferent second-order NTS neurons. The neurons exhibited a decreased spiking capacity, prolonged action potential duration, reduced afterhyperpolarization, decrease in peak and steady-state outward currents, and membrane depolarization. SHS exposure effects were mimicked by low concentrations of the K+ channel blockers 4-aminopyridine and/or tetraethyl ammonium. The data suggest that SHS exposure downregulates K+ channel function in a subset of NTS neurons, resulting in reduced cell excitability. The changes may help to explain the exaggerated neural reflex responses in children exposed to SHS.

• 出版日期2010-2