AJP - Heart and Circulatory Physiology, Vol 253, Issue 1 154-H164, Copyright © 1987 by American Physiological Society
Quantitative analysis of arteriolar network architecture in cat sartorius muscle
A. Koller, B. Dawant, A. Liu, A. S. Popel and P. C. Johnson
The geometry of the arteriolar network is one of the major determinants of
blood flow distribution within a tissue. The purpose of this study was to
describe the distribution of geometrical variables (lengths, diameters) as
well as the pattern of branching in the nonarcading portion of the
arteriolar network in skeletal muscle. The exteriorized cat sartorius
muscle was used as the experimental model. The intravascular fluorescence
of fluorescein isothiocyanate (FITC)-labeled Dextran 150 was observed with
a low-light-level video camera, and the vascular networks were mapped.
Arteriolar lengths and diameters were measured, and vessel position in the
network was characterized by Strahler's method of ordering, in which the
first-order arterioles give rise to most of the capillaries. Typically, the
nonarcading, terminal networks contain three or four arteriolar orders. The
sequences of the number of vessels, mean diameter, and mean length for each
order are accurately described by geometric progressions (Horton's law).
The distribution of diameters within each order was rather narrow:
typically two-thirds of the vessels fell within 20% of the mean value. The
spread was reduced by half when vessels within a single network were
considered. During vasodilation to a standard stimulus the relative
dispersion of diameters increased modestly. The distribution of vessel
lengths was broader than for diameters. Two-thirds of vessels of a single
order fell within 50-75% of the mean. The spread was less within individual
networks. The variability of vessel geometry and branching patterns was
substantially less within a single network than for a population drawn from
a group of networks.
