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INPUT IMPEDANCE OF THE CANINE VERTEBRAL ARTERY
Author(s) -
Taylor David E.,
Tukmachi Emad S.
Publication year - 1987
Publication title -
quarterly journal of experimental physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 101
eISSN - 1469-445X
pISSN - 0144-8757
DOI - 10.1113/expphysiol.1987.sp003061
Subject(s) - vertebral artery , electrical impedance , anatomy , internal carotid artery , medicine , carotid arteries , cardiology , physics , quantum mechanics
In experiments on six anaesthetized dogs it was found that the vertebral artery contributed 69·2 ± 1·7% of cerebral and 41·5 ± 2·5% of cephalic flow. The input characteristics were that the vertebral artery had a flow of 0·71 ± 0·05 ml.s −1 into an input impedance of 23·7 ± 1·9 GN.m −5 .s. This compared to external and internal carotid flows of 0·69 ± 0·05 and 0·31 ± 0·02 ml.s −1 into input impedances of 23·9 ± 2·1 and 52·1 ± 2·7 GN.m −5 .s respectively. Standardized per 100 g of tissue the impedances of the vertebral and internal carotid arteries were similar at 18·6 ± 2·0 and 19·1 ± 1·5 GN.m −5 .s.100 g −1 respectively, while that for the external carotid was higher at 129·9 ± 10·2 GN.m −5 .s.100 g −1 . The impedance spectrum for the vertebral artery was of low impedance type, settling about a characteristic impedance of 2·01 ± 0·28 GN.m −5 .s without significant oscillation, associated with the phase only becoming slightly positive above 10 Hz and reflexion coefficients of less than 0·25 by a frequency of 6 Hz. This was similar to the spectrum for the internal carotid artery and contrasted with the high impedance spectrum with major reflexion found for the external carotid artery.