Capillary Lengths and Anastomoses in Rat Hindlimb Muscles, Studied by Aquablak Perfusion During Rest Versus Exercise
An understanding of oxygen transport to tissue demands a knowledge of the three-dimensional arrangement of capillaries. In skeletal muscle the distribution of capillaries within the plane normal to the fiber axes has been studied extensively (see Plyley and Groom (1975), for review), whereas the network arrangement of capillaries in a plane parallel to the fiber axis has received relatively little attention. Plyley et al. (1976) and Honig et al. (1977) presented frequency distributions of the dimensions and interconnections of capillaries in frog sartorius and rat gracilis, respectively. They measured capillary pathlengths from terminal arteriole to collecting venule, segment lengths (i.e. distances between successive branch points) and the number of segments per path. Plyley’s measurements were made from muscle vasodilated with papaverine and perfused with a silicone elastomer (Microfil), whereas those of Honig were carried out in vivo under resting conditions and also following 2 min electrical stimulation. From a study of rat spinotrapezius muscles injected with India ink, Skalak and Schmid-Schonbein (1986) reported the presence of discrete microvascular units (‘capillary bundles’), and similar results have been obtained by Lund et al. (1987) from tibialis anterior of the hamster, using intravascular injection of fluorescein-labelled albumin to outline the capillary network.
KeywordsSegment Length Medial Gastrocnemius Capillary Network Gracilis Muscle Intracardiac Injection
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