Functional capillary organization in striated muscle

Abstract

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 x 10(5) microns 2; total segment length (sigma L) = 3.07 +/- 0.23, 2.15 +/- 0.21, and 3.02 +/- 0.45 x 10(3) microns; 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 O2 inflow: A = 2.03 +/- 0.32 x 10(5) microns 2; sigma L = 3.07 +/- 0.47 x 10(3) microns; 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 x 10(5) microns 2; sigma L = 2.31 +/- 0.23, 1.91 +/- 0.33, and 2.82 +/- 0.37 x 10(3) microns; N = 10.2 +/- 1.0, 7.8 +/- 1.3, and 11.0 +/- 1.4, at ages 51, 65, and 79 days, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

A computational model of oxygen delivery by hemoglobin-based oxygen carriers in three-dimensional microvascular networks

“…The number of capillaries in the tissue module agrees with experimental observation for the average number of capillaries supplied by a single arteriole (Berg and Sarelius, 1995). Twelve capillaries in a tissue block with a cross section of 100 × 100 μm 2 provide a capillary density (CD) of 1200 μm −2 , a value close to experimental observations (Ellsworth et al, 1988).…”

“…A tissue module is defined as the tissue block containing capillaries supplied by a single arteriole. For the particular tissue a module contains an average of approximately 12 capillaries (Berg and Sarelius, 1995). We define a unit tissue block of size 100 × 100 × 800 μm that contains capillaries from two modules feeding arterioles and draining venules.…”

Downstream Exposure to Growth Factors Causes Elevated Velocity and Dilation in Arteriolar Networks

“…This is based on our prior work showing that the excessred blood cell flux travels only to the stimulated downstream branch in experiments with α v β 3 integrin ligation [16]. Next we estimated the downstream surface area for exchange using a published value for a typical capillary grouping (module) with a total length of approximately 2,800 µm [28] and average capillary diameter of 5 µm (hamster red blood cell is 5 µm); surface area per module is 4.4 × 10 –4 cm 2 /module. The volume flow and surface area provided Jv/S from the Starling equation.…”

“…The arteriolar network is a repeating structure across the hamster cheek pouch tissue; they arise from (nonnutritive) arcading arterioles, and consist of a central feed arteriole and 3–7 terminal branch arterioles [16,25,26,27]. The terminal branch arterioles perfuse only capillaries [28]; thus, flow into these networks is solely nutritional. Similar arteriolar structures are seen in the cremaster muscle of the hamster, rat or mouse [10,29].…”

Network Vascular Communication Initiated by Increases in Tissue Adenosine

“…Observations were made at the inflow of a transverse arteriole (feed vessel), located in each preparation as described previously [7, 8]. This site was chosen for study because it is functionally an inflow to an arteriolar network; its branch arterioles directly feed adjacent capillary networks [9, 10]. …”