Cytotoxicity of snake venom Lys49 PLA2-like myotoxin on rat cardiomyocytes ex vivo does not involve a direct action on the contractile apparatus.

Viperid snake venoms contain a unique family of cytotoxic proteins, the Lys49 PLA homologs, which are devoid of enzymatic activity but disrupt the integrity of cell membranes. They are known to induce skeletal muscle damage and are therefore named 'myotoxins'. Single intact and skinned (devoid of membranes and cytoplasm but with intact sarcomeric proteins) rat cardiomyocytes were used to analyze the cytotoxic action of a myotoxin, from the venom of Bothrops asper.

CO2 Permeability of Rat Hepatocytes and Relation of CO2 Permeability to CO2 Production.

Background/aims: It has been described that cells in culture with very low oxidative metabolism possess a low CO2 membrane permeability, PCO2, of ∼ 0.01 cm/s. On the other hand, cardiomyocytes and mitochondria with extremely high rates of O2 consumption exhibit very high CO2 membrane permeabilities of 0.

CO₂ Permeability of Biological Membranes and Role of CO₂ Channels.

We summarize here, mainly for mammalian systems, the present knowledge of (a) the membrane CO₂ permeabilities in various tissues; (b) the physiological significance of the value of the CO₂ permeability;

CO2 and HCO3- Permeability of the Rat Liver Mitochondrial Membrane.

Background/aims: Across the mitochondrial membrane an exceptionally intense exchange of O2 and CO2 occurs. We have asked, 1) whether the CO2 permeability, PM,CO2, of this membrane is also exceptionally high, and 2) whether the mitochondrial membrane is sufficiently permeable to HCO3- to make passage of this ion an alternative pathway for exit of metabolically produced CO2.

Methods: The two permeabilities were measured using the previously published mass spectrometric 18O exchange technique to study suspensions of mitochondria freshly isolated from rat livers.