Tetrodotoxin-insensitive electrical field stimulation-induced contractions on Crotalus durissus terrificus corpus cavernosum

PLoS One. 2017 Aug 24;12(8):e0183766. doi: 10.1371/journal.pone.0183766. eCollection 2017.

Abstract

Reptiles are the first amniotes to develop an intromitent penis, however until now the mechanisms involved in the electrical field stimulation-induced contraction on corpora cavernosa isolated from Crotalus durissus terrificus were not investigated. Crotalus and rabbit corpora cavernosa were mounted in 10 mL organ baths for isometric tension recording. Electrical field stimulation (EFS)-induced contractions were performed in presence/absence of phentolamine (10 μM), guanethidine (30 μM), tetrodotoxin (1 μM and 1mM), A-803467 (10 μM), 3-iodo-L-Tyrosine (1 mM), salsolinol (3 μM) and a modified Krebs solution (equimolar substitution of NaCl by N-methyl-D-glucamine). Immuno-histochemistry for tyrosine hydroxylase was also performed. Electrical field stimulation (EFS; 8 Hz and 16 Hz) caused contractions in both Crotalus and rabbit corpora cavernosa. The contractions were abolished by previous incubation with either phentolamine or guanethidine. Tetrodotoxin (1 μM) also abolished the EFS-induced contractions of rabbit CC, but did not affect EFS-induced contractions of Crotalus CC. Addition of A-803467 (10 μM) did not change the EFS-induced contractions of Crotalus CC but abolished rabbit CC contractions. 3-iodo-L-Tyrosine and salsolinol had no effect on EFS-induced contractions of Crotalus CC and Rabbit CC. Replacement of NaCl by N- Methyl-D-glucamine (NMDG) abolished EFS-induced contractions of rabbit CC, but did not affect Crotalus CC. The presence of tyrosine hydroxylase was identified in endothelial cells only of Crotalus CC. Since the EFS-induced contractions of Crotalus CC is dependent on catecholamine release, insensitive to TTX, insensitive to A803467 and to NaCl replacement, it indicates that the source of cathecolamine is unlikely to be from adrenergic terminals. The finding that tyrosine hydroxylase is present in endothelial cells suggests that these cells can modulate Crotalus CC tone.

MeSH terms

  • Aniline Compounds / pharmacology
  • Animals
  • Callithrix
  • Crotalus / physiology*
  • Electric Stimulation*
  • Furans / pharmacology
  • Immunohistochemistry
  • Male
  • Muscle Contraction / drug effects
  • Penis / drug effects*
  • Penis / physiology
  • Rabbits
  • Receptors, Adrenergic / physiology
  • Sodium Channels / physiology
  • Tetrodotoxin / pharmacology*

Substances

  • A 803467
  • Aniline Compounds
  • Furans
  • Receptors, Adrenergic
  • Sodium Channels
  • Tetrodotoxin

Grants and funding

This study was supported by Fundação de amparo a pesquisa do estado de São Paulo (FAPESP; 2011/11828-4) (GDN) http://www.fapesp.br/ and by Conselho Nacional de Desenvolvimento científico e tecnológico (CNPq; 140731/2013-0) (RMC) http://cnpq.br/. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.