Local anaesthetics inhibit influx of calcium, sodium and potassium into rat ileum, diaphragm and human isolated saphenous vein.

The effects of 5 different local anaesthetics, lignocaine, prilocaine, etidocaine, mepivacaine, bupivacaine, on uptake of Ca2+, Na+ and K+ were studied, using a Kone Microlyte Analyzer, into 3 different types of muscle fibres, the rat ileum, rat diaphragm and human isolated saphenous vein. The aim of the present experiments was to see if local anaesthetics had a calcium antagonistic activity, like that produced by calcium antagonists, e.g. verapamil. The results showed that local anaesthetics in moderate and high concentrations (more than 100 microM) depressed uptake of Ca2+, as well as the Na+ and K+, although the depression of the uptake of Ca2+ was 7 and 2 times less than those of Na+ and K+. In low concentrations (1-10 microM), the local anaesthetics had no or little effect on Ca2+ uptake, although they still significantly reduced Na+ and K+ uptake. It was concluded that the effect of local anaesthetics on uptake of Ca2+, Na+ and K+ into rat ileum, diaphragm and human saphenous vein, is concentration-dependent, and that only at high concentrations do they have a calcium antagonistic activity in muscle. Furthermore, there was no clear evidence that the effect of local anaesthetics was species-dependent, since the uptake of Ca2+ was depressed by only about 17% more in smooth muscle than in skeletal muscle.