Innervation of guinea pig heart by neurons sensitive to capsaicin.
To determine the origin of non-vagal afferent fibers innervating the heart of guinea pigs, capsaicin was injected into the ventricular myocardium to induce depletion of substance P (SP). The lower cervical, upper thoracic and lumbar spinal ganglia, as well as the left atrium and base of ventricles, were assayed for SP depletion by using the enzyme-linked immunosorbent assay (ELISA) and immunohistochemical procedures. Capsaicin affected spinal ganglia from the 3 regions differently. The substance P level in lumbar spinal ganglia remained fairly constant, while the level of SP from cervical and thoracic regions declined significantly. At the maximal depletion dosage (173 micrograms of capsaicin/kg), SP concentration decreased 72.3% in cervical spinal ganglia, 45.5% in thoracic ganglia and 56.1% in the atrium. The lack of SP depletion in lumbar ganglia indicates that capsaicin acted locally on cardiac afferents rather than systemically. Data from this study suggest that capsaicin-sensitive neurons of the heart have cell bodies in the lower cervical spinal ganglia as well as in the upper thoracic spinal ganglia.
Hougland
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MW
Durkee
K H
KH
Hougland
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AE
D000818:Animals; D002211:Capsaicin / Q000494:pharmacology*; D004797:Enzyme-Linked Immunosorbent Assay; D005727:Ganglia, Spinal / Q000032:analysis / Q000187:drug effects / Q000378:metabolism; D006168:Guinea Pigs; D006321:Heart / Q000294:innervation*; D008297:Male; D009206:Myocardium / Q000032:analysis / Q000166:cytology*; D009475:Neurons, Afferent / Q000032:analysis / Q000187:drug effects* / Q000378:metabolism; D013373:Substance P / Q000378:metabolism
D013373:Substance P; D002211:Capsaicin