Increased autophagy in chloroquine-treated tonic and phasic muscles: an alternative view

Ultrastructural and cytochemical techniques were used to investigate autophagy in the tonic anterior(ALD) and phasic posterior (PLD) latissimus dorsi muscles of the chicken following chloroquine administration. Autophagic vacuoles were seen in the ALD after 1 day of chloroquine administration while no change was seen in the PLD until 3 days. In both muscles, autophagic vacuoles and myeloid bodies were found at the level of the I band. Myeloid bodies usually were found in the longitudinal rows of mitochondria in the ALD muscle. Some, but not all, of the autophagic vacuoles and myeloid bodies were cytochemically acid phosphatase positive, while the portion of the sarcoplasmic reticulum of both muscles which is normally acid phosphatase positive, while the portion of the sarcoplasmic reticulum of both muscles which is normally, acid phosphatase positive was devoid of activity following chloroquine administration. These observations are discussed in regard to accepted mechanisms of autophagy and the possible inhibition of autophagy in skeletal muscle tissue by chloroquine.