Capillary density measurements in skeletal muscle using immunohistochemical staining with anti-collagen type IV antibodies.

An immunohistochemical method, based on an indirect peroxidase method for staining of capillaries containing collagen type IV, is presented. Biopsies from the vastus lateralis muscle of eight endurance trained runners were stained and counted for capillaries with the collagen type IV method and with the widely used amylase-PAS method. The mean number +/- SEM of capillaries per fibre was 2.48 +/- 0.09 with the collagen type IV method and 2.41 +/- 0.09 with the collagen type IV method and 2.41 +/- 0.08 with the amylase method. The 95% confidence intervals for the differences between the two methods were - 0.03 to 0.15. We conclude that the collagen type IV immunohistochemical method for capillary staining is comparable with the amylase method under optimum conditions, but that it is likely to be more dependable. It also has the advantage that it reveals fibre outlines.