Anin vitro study into the mechanisms of lidocaine and befol actions on sodium exchange in normal and hypoxia-exposed rat cardiomyocytes

Using benzofuran isophthalate, a fluorescent probe for sodium ions, intracellular (sarcoplasmic) Na⁺ concentrations ([Na⁺]_i) were estimated in cardiomyocytes isolated from the left ventricle of rats. Lidocaine (1–100 μM) had little effect on [Na⁺]_i in resting (unstimulated) cardiocytes, while befol lowered it by virtue of its inhibitory effect on Na/H exchange. In cardiomyocytes exposed to “chemical” hypoxia (produced by 5 mM KCN+30 mM 2-deoxyglucoses). [Na⁺] were three times higher than in resting cells, and the Na-blocking effects of both lidocaine and befol were much stronger. When these two drugs were used together, potentiation of these effects was observed, which may be accounted for by their action on different Na-transporting systems. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 122, No. 5, pp. 45–47, July, 1996