Effects of ultrasound on skeletal and cardiac muscle in the ground squirrel

¹ Department of Anatomy, Louisiana State University School of Medicine, New Orleans, Louisiana

Adenosine triphosphate (ATP), phosphocreatine (PC), inorganic phosphate (IP), and glycogen were determined on skeletal and cardiac muscle samples from 28 nonhibernating and 10 hibernating ground squirrels, Citellus tridecemlineatus, following ultrasonic irradiation in vivo. A dosage of 0.13–3.0 w/cm² of 1 megacycle was applied for 3–6 minutes. The left legs and left half of the thorax were treated and the results compared with data from untreated animals. In studying the leg samples the treated and untreated sides of the experimental animal were compared. The phosphates, ATP and PC, were decreased significantly with slight changes in IP and glycogen. In both nonhibernating and hibernating animals the effects were seen in both legs signifying travel of the sound or a resultant effect. In both groups the changes took place without a change in the animal's rectal temperature. Histological study of samples from the treated legs revealed no changes in structure or glycogen and phosphate deposition. Ultrasound applied locally on the intact animal was followed by changes in compounds relevant to muscle contraction without apparent structural change.