Development of transmitter secretory mechanisms by adrenergic neurons in the embryonic chick heart ventricle☆

[摘要] Developmentalchangesinthefunctionofadrenergicaxonswithintherightventricleofthechickembryowereassessedbymeasuringtheabilityoftheseaxons(1)toreleaseendogenoustransmitter,and(2)totransport,retain,andreleasetritiatednorepinephrine([3H]NE).Thereleaseofendogenouscatecholamineswasassayedindirectlybymeasuringtheincreaseinthetwitchtensionofventricularmuscleevokedbyelectricalstimulationofintramuralnerves.Thereleaseofendogenoustransmitter,whichactedviaβ-adrenergicreceptors,wasfirstdetectedbythismethodonthe16thembryonicday.Acocaine-sensitiveuptakeof[3H]NEwasfirstobservedonthe12thembryonicday.Atthistime,elevatedpotassiumfirstevokedacalcium-sensitivereleaseof[3H]NE.Electricalstimulationofintramuralaxonsfirstevokedatetrodotoxin-sensitivereleaseof[3H]NEonthe14thembryonicday.Itisconcludedthattheaxonsofdevelopingadrenergicneuronsarecapableofreleasingtransmittersoonaftertheycontacttheirtargettissue.

[学科分类] 生物科学（综合）