[Effect of transition metal cations on Na+-Ca2+-exchange in cell membrane]

The possible mechanism of transient metals effect on Na(+)-CA2+ exchange of membrane in excitable and non-excitable cells has been examined on the basis of available literature and personal investigation. Different cations of transient metals can either inhibit or stimulate Na(+)-Ca2+ exchange depending on experimental conditions and their own properties. In some conditions these cations can even be translocated by the exchanger. Metal cations with the highest affinity to O-containing protein groups are able to inhibit the activity of exchanger due to the competition with Ca2+ within the transport site. Metal cations with the highest affinity of S-containing protein groups have stimulated the exchanger owing to their effect on the regulatory site. The total effect of different cations in each case is determined by the effectiveness of all these processes (inhibition, translocation and stimulation) which depends on the affinity of the cations to different protein functional groups. It has been assumed that complex investigation of the effect of different transient metals' cations is necessary for the revealing of Na(+)-Ca2+ exchange mechanism.