Regulation of brain temperature in pigeons: Effects of corneal convection

B. Pinshow, M. H. Bernstein, G. E. Lopez, S. Kleinhaus

Research output: Contribution to journalArticlepeer-review

28 Scopus citations

Abstract

The effect of direct ventilation of the eyes on cooling in the brain was investigated in domestic pigeons (Columba livia, mean mass 0.27 kg) with thermocouples chronically implanted in the hypothalamus and anterior eye chamber. During conductive heating in still air body-brain temperature difference (ΔT) was 2.6°C. During exclusive ventilation of ocular surfaces, with air flowing at about flight speed, ΔT increased to 3.5°C and returned to preventilation values on cessation of ventilation. When the eyes were sealed then ventilated, ΔT was not different from that in still air. Administration of phenylephrine caused iridial vasoconstriction and a significant decrease in intraocular temperature, but no changes in brain temperature. This suggests that compensation may occur via other evaporating cranial surfaces. Our findings suggest that the eyes contribute to the control of brain temperature by dissipating heat. Blood cooled while flowing through the ocular vasculature apparently contributes to the venous flow through the ophthalmic rete, serving as a heat sink for arterial blood flowing to the brain.

Original languageEnglish
Pages (from-to)R577-R581
JournalAmerican Journal of Physiology - Regulatory Integrative and Comparative Physiology
Volume11
Issue number3
DOIs
StatePublished - 1 Jan 1982

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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