Ma. Vincent et al., Spatial distribution of nutritive and nonnutritive vascular routes in perfused rat hindlimb muscle using microspheres, MICROVASC R, 61(1), 2001, pp. 111-121
Skeletal muscle appears to have two vascular flow routes, nutritive and non
nutritive, where the balance of flow is controlled by vasoconstrictors. In
the present study, spatial distributions of the two flow routes in muscles
of the perfused rat hindlimb were attempted using fluorescent microspheres
(15 mum in diameter). Microspheres were injected during steady-state perfus
ion with norepinephrine (proposed recruiter of nutritive flow), serotonin (
proposed recruiter of nonnutritive flow), or vehicle. The three-dimensional
location of individual microspheres in representative muscles was determin
ed using a Fluorescent Imaging CryoMicrotome. Norepinephrine and serotonin
each increased perfusion pressure (P < 0.05) but stimulated and inhibited o
xygen consumption (P < 0.05), respectively. The distribution of microsphere
s lodged in muscle was independent of the agent used. Spatial perfusion ind
ices for norepinephrine, serotonin, and vehicle did not differ from each ot
her. Similarly, there was no difference in these indices for a theoretical
distribution where microspheres were deliberately positioned in muscle bund
le capillaries or interfibrillar connective tissue vessels. We conclude tha
t the nutritive and nonnutritive flow routes are distributed throughout mus
cle sections consistent with their locations in muscle bundle capillaries a
nd interfibrillar connective tissue, respectively, (C) 2000 Academic Press.