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Alpha1- and alpha2-adrenoceptors at different levels of the canine saphenous vein

  • S. Guimarães
  • D. Moura
  • J. P. Nunes
  • M. J. Vaz-da-Silva
  • J. T. Guimarães
Conference paper
Part of the Journal of Neural Transmission book series (NEURAL SUPPL, volume 34)

Summary

Presynaptic alpha2- and postsynaptic alpha1-adrenoceptors were compared at the distal and proximal parts of the dog saphenous vein. The results obtained show that: (1) yohimbine is more effective against postsyaptic responses to phenylephrine distally than proximally. On the contrary, WB- 4101 is more effective proximally; (2) phenylephrine increases inositol monophosphate production at both levels, but the increase is more pronounced distally; (3) UK-14,304 and adrenaline reduce and yohimbine and phentolamine increase the release of 3H-noradrenaline caused by electrical stimulation at both levels. However, while adrenaline as well as the antagonists are equipotent at the two levels, UK-14,304 is more potent distally than proximally.

In conclusion, we suggest that: more alpha1A-adrenoceptors exist distally than proximally; imidazoline sites can exist at the distal level which contribute to the higher potency of UK-14,304 distally.

Keywords

Saphenous Vein Inositol Phosphate Distal Level Proximal Level Human Saphenous Vein 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag 1991

Authors and Affiliations

  • S. Guimarães
    • 1
  • D. Moura
    • 1
  • J. P. Nunes
    • 1
  • M. J. Vaz-da-Silva
    • 1
  • J. T. Guimarães
    • 2
  1. 1.Department of PharmacologyFaculty of MedicinePortoPortugal
  2. 2.Department of BiochemistryFaculty of MedicinePortoPortugal

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