Pre-junctional inhibitory action of prostaglandin E2 on excitatory neuro-effector transmission in the human bronchus.
The effects of prostaglandin E2 (PGE2) and indomethacin on excitatory neuro-effector transmission in the human bronchus were investigated by tension recording and microelectrode methods. PGE2 (10(-10)-10(-9)M) suppressed the amplitude of twitch contractions and excitatory junction potentials (e.j.ps) evoked by field stimulation at a steady level of basal tension obtained by the combined application of indomethacin (10(-5) M) and FPL55712 (10(-6) M). In doses over 10(-8)M, PGE2 reduced the muscle tone and dose-dependently suppressed the amplitude of twitch contractions. Indomethacin (10(-5) or 5 x 10(-5) M) reduced the muscle tone and enhanced the amplitude of twitch contractions and e.j.ps evoked by field stimulation in the presence of FPL55712. PGE2 (10(-9) M) had no effect on the post-junctional response of smooth muscle cells to exogenously applied acetylcholine (ACh) (4 x 10(-7) M). However, indomethacin (10(-5) M) significantly enhanced the ACh-induced contraction of the human bronchus. These results indicate that PGE2 in low concentrations has a pre-junctional action to inhibit excitatory neuro-effector transmission in addition to a post-junctional action, presumably by suppressing transmitter release from the vagus nerve terminals in the human bronchial tissues.
Ito
I
I
Department of Pharmacology, Faculty of Medicine, Kyushu University, Fukuoka, Japan.
Suzuki
H
H
Aizawa
H
H
Hirose
T
T
Hakoda
H
H
D001980:Bronchi / Q000187:drug effects / Q000294:innervation / Q000502:physiology*; D002867:Chromones / Q000494:pharmacology; D015232:Dinoprostone / Q000494:pharmacology*; D004558:Electric Stimulation; D006801:Humans; D066298:In Vitro Techniques; D007213:Indomethacin / Q000494:pharmacology; D007545:Isoproterenol / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects; D008839:Microelectrodes; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects / Q000294:innervation / Q000502:physiology; D009469:Neuromuscular Junction / Q000187:drug effects / Q000502:physiology*; D013189:SRS-A / Q000037:antagonists & inhibitors
D002867:Chromones; D013189:SRS-A; C006312:FPL 55712; D015232:Dinoprostone; D007545:Isoproterenol; D007213:Indomethacin