Functional capillary organization in striated muscle
Berg, B.R.; Sarelius, I.H.
American Journal of Physiology 268(3 Pt 2): H1215-H1222
1995
ISSN/ISBN: 0002-9513 PMID: 7900875 Document Number: 444485
In striated muscle, capillaries occur as independent network groups. Network architecture was quantitated in cremaster muscle of pentobarbital sodium-anesthetized hamsters in three age groups (51 +- 1 (SE), 65 +- 1, and 79 +- 1 days old). We observed that networks consist of independent subgroups of capillaries, called modules. Module architecture did not vary significantly with age during maximal dilation (Max, 10-4 M adenosine): tissue area (A) = 1.87 +- 0.16, 1.19 +- 0.13, and 1.81 +- 0.3 times 10-5 mu-m-2; total segment length (SIGMA-L) = 3.07 +- 0.23, 2.15 +- 0.21, and 3.02 +- 0.45 x 10-3 mu-m; and segment number (N) = 14.5 +- 1.1, 9.9 +- 1.1, and 12.6 +- 1.6, at ages 51, 65, and 79 days, respectively. Max module architecture was not different at 65 days of age at a second site of known higher O-2 inflow: A = 2.03 +- 0.32 times 10-5 mu-m-2; SIGMA-L = 3.07 +- 0.47 times 10-3 mu-m; and N = 13.1 +- 2.1. During control conditions (Rest) there was also no significant difference with age: A = 1.68 +- 0.18, 1.15 +- 0.19, and 1.64 +- 0.24 times 10-5 mu-m-2; SIGMA-L = 2.31 +- 0.23, 1.91 +- 0.33, and 2.82 +- 0.37 times 10-3 mu-m; N = 10.2 +- 1.0, 7.8 +- 1.3, and 11.0 +- 1.4, at ages 51, 65, and 79 days, respectively. High O-2 inflow modules were significantly different during Rest at 65 days of age: A = 2.21 +- 0.29 times 10-5 mu-m-2, SIGMA-L = 3.34 +- 0.52 times 10-3 mu-m, and N = 12.8 +- 2.0. The two-dimensional capillary length density (SIGMA-L/A) is invariant with age: 0.018 +- 0.001, 0.018 +- 0.001, and 0.020 +- 0.001 mu-m-1 at ages 51, 65, and 79 days, respectively. Networks are significantly different with age due to a decreased number of modules per network (Max: 5.7 +- 1.2, 3.2 +- 0.5, 2.6 +- 0.3 modules at ages 51, 65, and 79 days, respectively). High O-2 inflow networks were significantly larger at 65 days of age (Max: 6.5 +- 0.3 modules). Thus modules are an invariant unit of network architecture, and networks are larger in areas of expected higher flow due to the addition of modules. Differences between high and low O-2 inflow networks at Rest suggest possible differences in regulatory mechanisms.