PURPOSE The ultrafast extraocular muscles necessitate tight regulation of free cytosolic Ca2+ concentration ([Ca2+]i). Mitochondrial Ca2+ influx may be fast enough for this role. In the present study, three hypotheses were tested: (1) Mitochondrial Ca2+ uptake regulates [Ca2+]i and production of force in extraocular muscle; (2) mitochondrial content correlates with their use as Ca2+ sinks; and ...

Graves' ophthalmopathy is an autoimmune inflammatory process affecting primarily the extraocular muscles. The enlargement of these muscles is responsible for most of the important manifestations of the disease, including proptosis, lid retraction, diplopia, and optic neuropathy. Recently the optic neuropathy has been shown to correlate with extraocular muscle volume as determined by computed to...

Congenital fibrosis of the extraocular muscles is an autosomal dominant congenital disorder characterized by bilateral ptosis, restrictive external ophthalmoplegia with the eyes partially or completely fixed in an infraducted (downward) and strabismic position, and markedly limited and aberrant residual eye movements. It has been generally thought that these clinical abnormalities result from m...

The purpose of this study was to quantify the type and amount of myosin heavy chain (MHC) mRNA within muscles of different developmental origins to determine whether the regulation of gene expression is comparable. Seven MHC isoforms were analyzed in rat adult limb (extensor digitorum longus, tibialis anterior, and soleus) and nonlimb (extraocular, thyroarytenoid, diaphragm, and masseter) muscl...

Extraocular muscles differ from most other skeletal muscles in terms of constituent fiber types and innervation pattern. The rules that govern fiber responses to various experimental interventions for most skeletal muscles, therefore, may not strictly apply to the extraocular muscles. In this study, denervation of the extraocular muscles of Cynomolgous monkeys, Macaca fascicularis, was accompli...