The effect of α2-adrenergic receptors on cutaneous water evaporation in the rock pigeon (Columba livia)

Eshel Ophir, Yehuda Arieli, Jacob Marder

Research output: Contribution to journalArticlepeer-review

Abstract

The role of β-adrenergic receptors in regulating cutaneous water evaporation (CWE) in the rock pigeon (Columba livia) is well documented. Here, we studied the involvement of the α2-adrenergic receptors in this cooling mechanism of the heat-acclimated (HAc) pigeon. Systemic α2-adrenergic activation [clonidine, 50 μg kg-1, intramuscular (i.m.)] was found to increase CWE in heat-acclimated pigeons at an ambient temperature (Ta) of 25°C. Subcutaneous administration of the drug had no significant effect. Preinjection of an α2- adrenergic antagonist (yohimbine, 10 mg kg-1, i.m.) completely prevented clonidine-induced CWE and attenuated propranolol-induced CWE by 53%. Pretreatment with a β-adrenergic agonist (isoproterenol, 4 mg kg -1, i.m.) abolished the effect of clonidine. None of the above treatments was found to elicit significant CWE in nonacclimated (NAc) pigeons. These findings, in addition to previously reported data, indicate a complex regulatory pathway of CWE in the heat-acclimated pigeon consisting of α2- and β2-adrenergic receptors. The possible hierarchical pattern of these receptors is discussed.

Original languageEnglish
Pages (from-to)411-415
Number of pages5
JournalComparative Biochemistry and Physiology - A Molecular and Integrative Physiology
Volume139
Issue number4
DOIs
StatePublished - Dec 2004
Externally publishedYes

Keywords

  • Birds
  • Clonidine
  • Cutaneous water evaporation
  • Heat-acclimation
  • Pigeon
  • Skin
  • Thermoregulation
  • α-Adrenergic receptors

ASJC Scopus subject areas

  • Molecular Biology
  • Biochemistry
  • Physiology

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