DIRECT MICROCALORIMETRY AS A TECHNIQUE IN CELL-CULTURES

In vitro studies of energy metabolism in isolated cells contribute to improved knowledge of human energy metabolism under normal and patholo gical conditions. In every cellular system energy is taken up, metabol ized and finally transformed into heat, which is dissipated into the e nvironment. Thus, energy turnover of isolated cells can be assessed by microcalorimetric determination of their heat production. Microcalori meters of the thermopile heat conduction type facilitate direct physic al determination of thermogenesis with a sensitivity of 0.2 mu W; 10(4 )-10(5) cells being sufficient for one measurement. Peltier elements a re sandwiched between the sample and a precisely thermostated heat sin k, creating a detectable voltage proportional to the heat production. For adequate interpretation of the results, simultaneous biochemical i nvestigations of relevant metabolic pathways are required. Up to now, numerous studies with blood cells, skeletal and heart muscle cells, he patocytes, endothelial cells, fibroblasts and adipocytes have been per formed in relation to various diseases and under the influence of cert ain hormones and pharmacological agents.