High correlation of fractals for regional blood flows among resting
and exercising skeletal muscles.
Iversen, Per Ole, and Gunnar Nicolaysen.
Department of Physiology, Institute of Basic Medical Sciences,
University of Oslo, Norway
APStracts 2:0063H, 1995.
The regional blood flow distributions within single skeletal muscles
are markedly uneven both at rest and during exercise hyperemia.
Fractals adequately describe this perfusion heterogeneity in the
resting lateral head of the gastrocnemius muscle as well as in the
myocardium. Recently we provided evidence that the fractal dimension
for the blood flow distributions in this resting muscle was strongly
correlated with that of the myocardium in the same rabbit. Prompted
by this hitherto unknown observation, we have now examined (i) if
fractals also describe perfusion distributions within muscles with a
varying metabolic activity, and (ii) if the fractal dimensions for
blood flow distributions to these muscles were correlated. We used
barbital anesthetized rabbits and cats. The regional distributions of
blood flow within various skeletal muscles were estimated by
microsphere trapping. The data unequivocally showed that the
perfusion distributions could be described with fractals both in
resting and in exercising muscle in both species, the corresponding
fractal dimensions ranging from 1.36 to 1.41. The fractal dimensions
were markedly correlated ( r2 ranged from 0.82 to 0.88) both when
various resting, and when resting and exercising muscles were
compared in the same animal. This surprising finding of high
correlations for the fractal dimensions among various muscles within
one animal, provides a novel characteristic of blood flow
heterogeneity.
Received 3 November 1994; accepted in final form 21 February
1995.
APS Manuscript Number H977-4.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 10 March 1995.