Parts of this study were presented at the 72nd American Heart Association Scientific Sessions, 10 November 1999, in Atlanta.
The I allele of the angiotensin-converting enzyme gene is associated with an increased percentage of slow-twitch type I fibers in human skeletal muscle
Article first published online: 10 MAR 2003
Volume 63, Issue 2, pages 139–144, February 2003
How to Cite
Zhang, B., Tanaka, H., Shono, N., Miura, S., Kiyonaga, A., Shindo, M. and Saku, K. (2003), The I allele of the angiotensin-converting enzyme gene is associated with an increased percentage of slow-twitch type I fibers in human skeletal muscle. Clinical Genetics, 63: 139–144. doi: 10.1034/j.1399-0004.2003.00029.x
- Issue published online: 10 MAR 2003
- Article first published online: 10 MAR 2003
- Received 8 August 2002, revised and accepted for publication 9 October 2002
- ACE genotype;
- exercise endurance;
- muscle biopsy;
- muscle fiber type;
- skeletal muscle
The insertion (I) allele of the human angiotensin-converting enzyme (ACE) gene is associated with lower serum and tissue ACE activity, and with greater endurance performance and enhanced mechanical efficiency of trained muscle. We tested the hypothesis that the ACE-I allele may be associated with increased slow-twitch fiber, which is more efficient than fast-twitch fiber in low-velocity contraction, by examining the association between the ACE genotype and skeletal muscle fiber (SMF) types in 41 untrained healthy young volunteer subjects (31 males, 10 females, age 24 ± 3 years). Skeletal muscle samples were taken from the left vastus lateralis using the needle-biopsy method. Slow-twitch type I fibers and fast-twitch type IIa and IIb fibers were classified histochemically based on staining for myosin adenosine triphosphatase (ATPase) activity at different pH values. Amylase-periodic acid-Schiff staining was used to visualize capillaries around fibers. ACE-II subjects had significantly (p < 0.01) higher percentages of type I fibers (50.1 ± 13.9%vs 30.5 ± 13.3%) and lower percentages of type IIb fibers (16.2 ± 6.6%vs 32.9 ± 7.4%) than ACE-DD subjects. The linear trends for decreases in type I fibers and increases in type IIb fibers from ACE-II → ID → DD genotypes were significant as assessed by an analysis of variance. The ratio of type I:II fibers also differed according to the ACE genotype. A multivariate logistic regression analysis showed that the ACE-I allele had significant additive and recessive (codominant) effects on the increased type I fibers and the ratio of type I:II fibers. No specific pattern of capillarization was observed among the three ACE genotypes. In conclusion, the ACE-I allele was associated with increased type I SMF, which may be a mechanism for the association between the ACE genotype and endurance performance.