[Disorder of swallowing muscles in iron deficient rabbits]

Plummer-Vinson syndrome is a clinical entity associated with dysphagia, sideropenic anemia and atrophic glossitis. Using rabbits with iron deficiency anemia, the author investigated the cause of dysphagia in this syndrome. Iron deficient animals were produced by bolus feeding without iron and intramuscular injection of an iron-chelating agent. The fibers of swallowing muscles (the thyro-pharyngeal, cricopharyngeal and cervicoesophageal muscles) were classified into three types (Type 1, 2A and 2B fibers) by actomyosin ATPase staining. No significant difference between the muscles of sideropenic rabbits and those of normal rabbits were found in the composition and distribution of their muscle fibers. By NADH-TR staining, however, the disturbance of the intermyofibrillar network and/or a "Moth Eaton" appearance, known to be caused by leakage of mitochondria, were observed in Type 1 fibers of the swallowing muscles of sideropenic rabbits. These morphological changes are similar to those observed in progressive muscular dystrophy. The quantity of iron in the swallowing muscles of sideropenic rabbits was significantly reduced in comparison with that in the sternothyroid and femoral muscles. This finding suggests that a selective decrease in myoglobin occurs in the swallowing muscles of iron deficient animals. From these observations, it might be concluded that dysphagia in iron deficiency anemia is caused by a myogenic disorder.