Reflex and local thermal control of rabbit ear blood flow
Roberts, M.F.; Zygmunt, A.C.
American Journal of Physiology 246(6 Pt 2): R979-R984
1984
ISSN/ISBN: 0002-9513 PMID: 6742178 Document Number: 235992
Thermal conductance (K) of the ears of 12 New Zealand White rabbits was measured during periods of core heating in which mean skin temperature and ear temperatures (Te) were controlled. Right Te was always held at 28.degree. C; left Te was 15.degree., 20.degree., 24.degree., 28.degree., 31.degree. or 33.degree. C in separate core heating periods. Core heating was obtained by perfusing a previously implanted intravascular heat exchanger with hot water. Blood temperature (Tbl) was measured with a thermocouple that had been previously placed in contact with the common carotid artery. During heating, K rose with rising Tbl, but relation between K and Tbl depended on Te. At high Te, K rose rapidly in the initial stages of core heating and soon reached its maximal value. At cool Te, K rose slowly with rising Tbl until high Tbl was reached; the K rose rapidly to maximal values. The maximal value of K reached at high Tbl was independent of Te. Local temperature evidently affects ear blood flow by affecting the way that ear blood vessels react to sympathetic reflex signals.