Mechanism of liposoluble drugs and general anaesthetic's membrane action: action of difluorodichloromethane (FC 12) on different types of cardiac fibres isolated from sheep hearts.

The effect of difluorodichloromethane (FC 12), a chemically stable aerosol propellant which has long been considered innocuous, on several types of cardiac fibres isolated from sheep hearts after preparation in a nutritive solution was studied. Modifications in resistance and transmembrane potentials suggested a mechanism of FC 12 action. Physical constraint on membrane structures produced by high FC 12 concentrations from simple dissolution in the internal lipid layer explain modifications in cardiac membrane properties. Variable effects of FC 12 with localisation and time on automatism, excitability, and conduction in various types of cardiac tissue agreed with earlier observations of the depressive and arrhythmia effect of this gas on isolated and in situ hearts.