[Roentgenological and pathomorphological changes in the canine heart during 6-months hypokinesia]

The effect of 6-month hypokinesia on the cardiac function and pathomorphological changes in 8 dogs was investigated. The heart size during systolic and diastolic contractions, stroke volume and contractile function were measured once a month, using an X-ray unit and a kymograph. After the hypokinetic exposure 6 dogs were sacrificed and their hearts were examined morphologically and histochemically. The recovery processes were investigated on 2 other dogs that were allowed to survive for 30 days after exposure. The 6-month hypokinesia led to a significant decrease in the heart size, stroke volume, cardiac index, and the contractile function. Post-mortem morphological examinations revealed atrophic changes in the myocardium. Electron-microscopy investigations demonstrated focal destructive changes in myofibers and in mitochondria: some of them were denser while others had a more transparent matrix and degraded crystae. Histochemical data (increased acid and alkaline phosphatase) also suggested atrophic and destructive changes in the myocardium. The above changes did not return to normal within 30 days of the recovery period.