Effects of heat shock on the functional morphology of cell organelles observed by video-enhanced microscopy

In living astrocytes and MDCK cells we observed morphological phenomena dur ing and after heat shock (HS) utilizing our new perfusable microchamber sys tem, which monitors pH, pO(2), pCO(2), and temperature. By means of electro nic light microscopy and confocal laser scanning microscopy, mitochondria w ere demonstrated to swell and to reduce their motility. The specific fluore scent probe MitoTracker Green revealed that the mitochondrial morphology ch anged from a rodlike into an annular shape with a central vacuole-findings which were corroborated by transmission electron microscopy. After HS (shif t from 37 degrees C to 45 degrees C for 15 min) the mitochondrial membrane potential (Delta Psi(m)) was depressed in most but not all mitochondria as monitored with the fluorescent probe JC-1. The dual emission images of JC-1 illustrated a heterogeneous red staining of distinct areas of single mitoc hondria. The shape changes as well as the drop of the membrane potential of the mitochondria indicated severe cellular stress and a direct interventio n on the mitochondrial permeability transition. Anat Rec 255:458-464, 1999. (C) 1999 Wiley-Liss, Inc.