Evidence that tachykinins are the main NANC excitatory neurotransmitters in the guinea-pig common bile duct

摘要

Application of electrical field stimulation (EFS; trains of 10 Hz, 0.25 ms pulse width, supramaximal voltage for 60 s) to the guinea-pig isolated common bile duct pretreated with atropine(1μM), produced a slowly-developing contraction('on' response) followed by a quick phasic 'off' contraction('off peak' response) and a tonic response ('off late' response), averaging 16±2, 73±3 and 20±4/100 of the maximal contraction to KCl (80 mM), n =20 each, respectively. Tetrodotoxin(1 μM; 15 min before) abolished the overall response to EFS (n =8). Neither in vitro capsaicin pretreatment (10 μM for 15 min), nor guanethidine (3 μM, 60 min before) Affected the excitatory response to EFS(n =5 each), showing that neither primary sensory neurons, nor Sympathetic nerves were involved.