[Correlation of mitochondrial adenosine triphosphatase activity with their size following exposure of cells to higher...

Cells of the Unio tumidus gill ciliated epithelium were exposed to a supraoptimal temperature of 40 degrees C for the period from 30 seconds till a complete cessation of ciliar beating. ATPase activity of mitochondria of these cells being checked against their size during the corresponding period. The mitochondria were found to change their size in a phasic manner, swelling at the beginning of the temperature exposure, then shrinking and then swelling again. The ATPase activity increased during the first swelling and during shrinking to the control level. The data obtained indicate that similar ultrastructure and size of mitochondria may correspond to different levels of their functional activity.