목적: 사람 외안근에서 myosin heavy chain (MyHC) 아형의 분율을 알아보고, 외안근을 중심부와 말단부로 나누어 MyHCeom을 포함한 MyHC 아형의 분율을 비교하고자 한다. 대상과 방법: 세 뇌사 환자의 기증안(6안)을 대상으로 모든 외안근을 적출한 후, 각각의 외안근을 중심부와 말단부로 나누어 MyHC 아형의 분율에 대해 전기영동 및 densitometer를 통하여 정량 분석을 시행하였다. 결과: 전기영동 결과 MyHCI, MyHCeom, MyHCIIa, MyHCIIx 아형이 관찰되었다. MyHCeom의 분율은 말단부보다 중심부에서 높았으며, MyHCIIa의 경우 반대로 말단부에서 중심부보다 높았다. MyHCI, MyHCeom, MyHCIIa는 네 개의 직근 및 하사근에서 모두 비슷한 분율을 나타내었으며, MyHCIIx의 경우 하직근에서 높은 분율을 보였다. 결론: 외안근에서 특징적으로 발견되는 MyHCeom의 분율은 외안근의 말단부보다 중심부에서 높게 측정되었다. 이와 같은 분포가 외안근의 기능에 미치는 영향에 대한 향후 연구가 필요할 것으로 생각된다.

Purpose: To provide quantitative data on the distribution of MyHCeom and compare the proportion of myosin heavy chain (MyHC) isoforms between the central and peripheral regions of human extraocular muscles (EOMs). Methods: Medial rectus, lateral rectus, superior rectus, inferior rectus, superior oblique, and inferior oblique muscle samples were taken from three men with brain death. To examine the longitudinal distribution of myosin isoforms, the muscles were divided into central and peripheral portions of equal length. Electrophoresis and densitometry were used to quantify the distribution of MyHC isoforms. Results: Electrophoresis of whole‐muscle extracts of sampled EOMs revealed four MyHC bands that were identified as MyHCI, MyHCeom, MyHCIIa, and MyHCIIx. The proportion of MyHCeom was higher in the central region, whereas the proportion of MyHCIIa was higher in the peripheral region. The relative proportions of MyHCI, MyHCeom, and MyHCIIa were not significantly different among the EOMs. There was a tendency for higher levels of MyHCIIx in the inferior rectus muscle. Conclusions: The proportion of MyHCeom was higher in the central region of human EOMs. Further studies are needed to investigate the consequences of this distributional difference on the function of EOMs.

Purpose: To provide quantitative data on the distribution of MyHCeom and compare the proportion of myosin heavy chain (MyHC) isoforms between the central and peripheral regions of human extraocular muscles (EOMs). Methods: Medial rectus, lateral rectus, superior rectus, inferior rectus, superior oblique, and inferior oblique muscle samples were taken from three men with brain death. To examine the longitudinal distribution of myosin isoforms, the muscles were divided into central and peripheral portions of equal length. Electrophoresis and densitometry were used to quantify the distribution of MyHC isoforms. Results: Electrophoresis of whole‐muscle extracts of sampled EOMs revealed four MyHC bands that were identified as MyHCI, MyHCeom, MyHCIIa, and MyHCIIx. The proportion of MyHCeom was higher in the central region, whereas the proportion of MyHCIIa was higher in the peripheral region. The relative proportions of MyHCI, MyHCeom, and MyHCIIa were not significantly different among the EOMs. There was a tendency for higher levels of MyHCIIx in the inferior rectus muscle. Conclusions: The proportion of MyHCeom was higher in the central region of human EOMs. Further studies are needed to investigate the consequences of this distributional difference on the function of EOMs.