Submitted on January 8, 2007
Accepted on July 30, 2007
Stereological Estimates Indicate That Aging Does Not Alter the Capillary Length Density in the Human Posterior Cricoarytenoid Muscle
Michael John Lyon1*, Linda M Steer2, and Leslie T Malmgren1
1 Otolaryngology, SUNY Upstate Medical University, Syracuse, New York, United States
2 Otolaryngolgoy, SUNY Upstate Medical University, Syracuse, New York, United States
* To whom correspondence should be addressed. E-mail: lyonm{at}upstate.edu.
Studies of some human skeletal muscles demonstrate an age-related capillarity decrease. An age-related decrease in blood flow to the posterior cricoarytenoid muscle (PCA) in rats has been reported as well as a decreased ability to abduct the vocal folds. We therefore hypothesized that decreased muscle capillarity may contribute to PCA dysfunction in the elderly. Using immunological and stereological techniques, human PCAs (ages 18-98 years; 28 males, 23 females) were examined for age-related changes in muscle fiber type specific and/or total capillary length density. While analysis shows no age-related changes in total muscle or fiber type specific capillary length densities (LV cap), there are significant age-related increases in LV cap within the interstitial tissue (P = 0.001) and in the ratio of the type I LV cap to fiber type specific surface density (SV ft, mus; P = 0.002) with a strong trend for type II LV cap (P = 0.055). There is also an age-related decrease in the muscle fiber surface density for both type I and II fibers (P < 0.001, 0.04 respectively). Data also show that females have a significantly higher type II LV cap (P = 0.039), regardless of age. In addition, with the exception of female type I LV cap, all measured variables are significantly higher for type I fibers (P < 0.001), independent of age or sex. While data indicate there are age-related changes of capillary-muscle fiber relationships within the PCA, they do not support the hypothesis of an age-related loss of capillarity.
