Neurokinin A with K+ channel blockade potentiates contraction to electrical stimulation in human bronchus.
This study investigated the effects of neurokinin A (NKA) on cholinergic neural responses in human bronchus. NKA (0.1 nM) did not alter the contractile response to submaximal electrical field stimulation. However, K+ channel blockade with 4-aminopyridine (4-AP) (0.1 mM) potentiated the response to electrical field stimulation (to 182 +/- 25% of control, n = 4, P less than 0.05) and subsequent addition of NKA in the presence of 4-AP produced further potentiation (to 123 +/- 6% of the response to 4-AP n = 4, P less than 0.05). Neither 4-AP (0.01 or 0.1 mM) nor NKA in the presence of 4-AP potentiated the actions of exogenous acetylcholine but in these experiments 4-AP itself produced a marked direct contractile response. Thus NKA in the presence of K+ channel blockade potentiates cholinergic neural response in human bronchus and this occurs at a prejunctional site.
Black
J L
JL
Department of Pharmacology, University of Sydney, N.S.W., Australia.
Johnson
P R
PR
Alouan
L
L
Armour
C L
CL
D015761:4-Aminopyridine / Q000494:pharmacology; D000109:Acetylcholine / Q000494:pharmacology; D001980:Bronchi / Q000502:physiology; D004558:Electric Stimulation; D004594:Electrophysiology; D006801:Humans; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects*; D015288:Neurokinin A / Q000494:pharmacology*; D010275:Parasympathetic Nervous System / Q000187:drug effects; D015221:Potassium Channels / Q000187:drug effects*; D009435:Synaptic Transmission / Q000187:drug effects; D013757:Tetraethylammonium Compounds / Q000494:pharmacology
D015221:Potassium Channels; D013757:Tetraethylammonium Compounds; D015288:Neurokinin A; D015761:4-Aminopyridine; D000109:Acetylcholine