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Cholinergic regulation along the pulmonary arterial tree of the South American rattlesnake: vascular reactivity, muscarinic receptors, and vagal innervation

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  • Renato Filogonio, Universidade Federal de Sao Carlos
  • ,
  • Marina R. Sartori, Universidade de Sao Paulo
  • ,
  • Susie Mogensen
  • Driele Tavares, Universidade Federal de Sao Carlos
  • ,
  • Rafael Campos, Universidade Estadual do Ceara
  • ,
  • Augusto S. Abe, Universidade de Sao Paulo
  • ,
  • Edwin W. Taylor, Universidade Federal de Sao Carlos, University of Birmingham
  • ,
  • Gerson J. Rodrigues, Universidade Federal de Sao Carlos
  • ,
  • Gilberto De Nucci, Universidade Estadual de Campinas
  • ,
  • Ulf Simonsen
  • Cléo A.C. Leite, Universidade Federal de Sao Carlos
  • ,
  • Tobias Wang

Vascular tone in the reptilian pulmonary vasculature is primarily under cholinergic, muscarinic control exerted via the vagus nerve. This control has been ascribed to a sphincter located at the arterial outflow, but we speculated whether the vascular control in the pulmonary artery is more widespread, such that responses to acetylcholine and electrical stimulation, as well as the expression of muscarinic receptors, are prevalent along its length. Working on the South American rattlesnake (Crotalus durissus), we studied four different portions of the pulmonary artery (truncus, proximal, distal, and branches). Acetylcholine elicited robust vasoconstriction in the proximal, distal, and branch portions, but the truncus vasodilated. Electrical field stimulation (EFS) caused contractions in all segments, an effect partially blocked by atropine. We identified all five subtypes of muscarinic receptors (M1-M5). The expression of the M1 receptor was largest in the distal end and branches of the pulmonary artery, whereas expression of the muscarinic M3 receptor was markedly larger in the truncus of the pulmonary artery. Application of the neural tracer 1,1'-dioctadecyl-3,3,3',3'-tetramethylindo-carbocyanine perchlorate (DiI) revealed widespread innervation along the whole pulmonary artery, and retrograde transport of the same tracer indicated two separate locations in the brainstem providing vagal innervation of the pulmonary artery, the medial dorsal motor nucleus of the vagus and a ventro-lateral location, possibly constituting a nucleus ambiguus. These results revealed parasympathetic innervation of a large portion of the pulmonary artery, which is responsible for regulation of vascular conductance in C. durissus, and implied its integration with cardiorespiratory control.

Original languageEnglish
JournalAmerican Journal of Physiology: Regulatory, Integrative and Comparative Physiology
Pages (from-to)R156-R170
Publication statusPublished - 1 Aug 2020

    Research areas

  • cardiorespiratory integration, electrical field stimulation, intracardiac shunts, respiratory sinus arrythmia, vagus nerve

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