Distribution of synaptic boutons around identified neurones lying in the cardiac plexus of the guinea-pig.
Neurones in the cardiac plexus of the guinea-pig were subdivided into three groups according to their electrophysiological properties and subsequently labelled with neurobiotin. Preparations were counterstained with antibodies to synaptophysin to reveal boutons containing synaptic vesicles. Two of the three groups of cells which, in the electrophysiological studies were found to receive excitatory synaptic inputs were associated with numerous synaptophysin positive boutons. Cells of the other group, which did not appear to receive any synaptic inputs were associated with fewer synaptophysin positive boutons. Wholemount preparations were double stained with antibodies to Protein Gene Product 9.5 and synaptophysin. This revealed most neurones, along with vesicle filled boutons. Ganglia generally contained less than 10 neurones with a range between one and over 30. In wholemount preparations it was found that about 90% of the cells were associated with a large number of synaptophysin positive boutons whilst the remaining cells were associated with very few synaptophysin positive boutons. These results are consistent with the idea that a proportion of cardiac ganglion cells fail to receive a synaptic input and suggest that by staining wholemount preparations of guinea-pig cardiac plexus with antibodies to synaptophysin it is possible to differentiate between groups of cells which receive a synaptic input and those which fail to receive a synaptic input. Approximately 10% of intrinsic cardiac neurones appear to lack a synaptic input.
Klemm
M F
MF
Department of Zoology, University of Melbourne, Parkville, Vic., Australia.
Wallace
D J
DJ
Hirst
G D
GD
D000818:Animals; D004594:Electrophysiology; D005260:Female; D005725:Ganglia, Autonomic / Q000502:physiology; D006168:Guinea Pigs; D006321:Heart / Q000294:innervation* / Q000502:physiology; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D008297:Male; D009206:Myocardium / Q000648:ultrastructure; D009474:Neurons / Q000502:physiology* / Q000648:ultrastructure; D013569:Synapses / Q000502:physiology* / Q000648:ultrastructure; D016708:Synaptophysin / Q000378:metabolism / Q000502:physiology; D013869:Thiolester Hydrolases / Q000378:metabolism; D043222:Ubiquitin Thiolesterase
D016708:Synaptophysin; D013869:Thiolester Hydrolases; D043222:Ubiquitin Thiolesterase