OUABAIN AND DIGITOXIN AS MODULATORS OF CHICK-EMBRYO CARDIOMYOCYTE ENERGY-METABOLISM

The effects of 0.1 nmol/l ouabain (CAS 630-60-4) and digitoxin (CAS 71 -63-6) on oxygen consumption rate (OCR) and the contractility of cultu red chick embryo cardiomyocytes were investigated using a perfusion sy stem which allowed microscopic observation during the experiment. cont ractility was assessed by a novel image analysis procedure. During sub strate free perfusion the OCR was increased on application of 0.1 nmol /l ouabain or digitoxin for 60 min, whilst conrtractility was not affe cted. Digitoxin (0.1 nmol/l) elicited no change in the OCR in the pres ence of glucose, pyruvic acid, lactic acid and caprylic acid. Ouabain (0.1 nmol/l) did not affect the OCR or contractility in the presence o f glucose, pyruvic acid and lactic acid, however together with capryli c acid the OCR was increased significantly. These results demonstrate a hitherto unknown stimulation of fatty acid utilization by low concen trations of ouabain.