Distribution of Myosin Heavy Chain Isoforms in the Musculus Uvulae of Patients with Snoring and Obstructive Sleep Apnea Syndrome Using ATPase Staining Method / 대한이비인후과학회지

ABSTRACT

BACKGROUND AND OBJECTIVES: OSAS is thought to be due to an excessive loss of muscle tone in the upper airway or an abnormal reflex regulation of upper airway function during sleep. The aim of this study was to investigate the distribution of myosin heavy chain (MHC) isoforms of musculus uvulae in OSAS and snorers. Materials and Methods: Thirty seven patients included in the study underwent an uvulo-palato-pharyngoplasty (UPPP). All subjects had polysomnographic study before UPPP. ATPase stain at pH 9.4 were applied to muscle specimens obtained during UPPP. The numbers of MHC type I and II isoforms were counted. The patients were divided into three groups according to their repiratory disturbance index (RDI)mild (0-20), moderate (21-40), severe (>40). The differences in the distribution of muscle fiber types were compared between these groups. The correlation between the distribution of the fibers and the body mass index / age / RDI / minimum O2 saturation / duration of sleep apnea was investigated. RESULTS: The mean percentages standard deviation of type I fibers according to the severity of sleep apnea were as follows22.5+/-3.2% in mild sleep apnea group (n=5), 19.8+/-2.3% in moderate sleep apnea group (n=1), 17.5+/-3.6% in severe sleep apnea group (n=1). There were statistically significant differences in the distribution of MHC type I and II isoforms between mild group and moderate and / or severe group (p.05). CONCLUSION: The proportion of MHC type I isoforms in musculus uvulae was decreased according to the severity and duration of sleep apnea (p<.01).