Maintenance of heterogeneity of capillary spacing is essential for adequate oxygenation in the soleus muscle of the growing rat

Microcirculation. 2006 Sep;13(6):467-76. doi: 10.1080/10739680600776286.

Abstract

Objectives: Normal muscle growth is accompanied by capillary proliferation, which usually lags behind the increase in muscle size, causing a decline in mean capillary density (CD). It is not known, however, how the capillary distribution is affected and what impact it has on the oxygenation of the muscle.

Methods: The capillarization of soleus muscles of rats (64-425 g) was determined with the method of capillary domains. As well as quantifying CD, capillary to fiber ratio (C:F), and fiber size, this method provides a measure of the heterogeneity of capillary spacing. Capillary locations were used to mathematically model oxygenation levels within the muscle.

Results: The increase in muscle mass was largely attributable to 5-fold increase in fiber size, accompanied by a more than 3-fold rise in C:F. The mismatch between rates of angiogenesis and muscle growth resulted in a decrease in CD. However, the heterogeneity of capillary spacing was unaffected (heterogeneity index logRSD: 0.091 +/- 0.013; mean +/- SD) as was muscle PO2, with modal values between 4 and 60 mmHg (0.5 and 8 kPa).

Conclusions: Angiogenesis during normal muscle growth does not maintain CD, but with similar heterogeneity of capillary spacing it preserves the potential for adequate intramuscular oxygenation.

MeSH terms

  • Animals
  • Male
  • Microcirculation / physiology
  • Models, Cardiovascular*
  • Muscle Development / physiology*
  • Muscle, Skeletal / blood supply*
  • Muscle, Skeletal / growth & development*
  • Muscle, Skeletal / metabolism
  • Neovascularization, Physiologic*
  • Oxygen Consumption / physiology*
  • Rats
  • Rats, Wistar