Electrically stimulated cardiomyocytes: evaluation of shortening, oxygen consumption and tracer uptake

Progress in the utilisation of the model "isolated cardiac myocytes" was achieved by designing a special stimulation chamber. This chamber allows eliciting of contraction of suspended myocytes by electrical stimulation. Oxygen consumption was thereby linearly enhanced dependent on the rate of stimulation. Different extent of shortening was observed indicating different inotropic state. Considering the myocytes to behave as a spring (with small delta L) a correlate to work performed was obtained which allowed evaluation of changes in ATP/O-ratios. Uptake of 3-O-methyl-D-glucose was dependent on the mechanical and therefore metabolic activity of the cells. The results show that transfer of glucose across the myocardial sarcolemma is adapted to the metabolic demand by affinity variation and not by recruitment of the transporters.