Direct or indirect influence of triphenyl-lead on activity of Na+/K+-ATPase

Abstract

We have studied the effect of triphenyl-lead chloride on the lipid phase of erythrocyte membranes, on lipid monomolecular layers and Na /K -ATPase of the microsomal fraction of rat brain. It was found that the haemolytic effect induced by this compound occurs when its concentration exceeds 30 mM. The minimal lead concentration inducing measurable effects in monomolecular lecithin layers is about 1 mM. Inhibition of Na /K -ATPase activity begins at a concentration exceeding 0.5 mM. Maximum inhibition is observed at around 40 mM-a concentration at which haemolysis also occurs. It can thus be thought that at very low lead concentrations the main (or exclusive) role in modifying membrane function is played by direct interaction between lead and the sulphydryl groups of ATPase, whereas at higher concentrations two effects seem to overlap: direct interaction between lead and enzymic proteins via their sulphydryl groups and as indirect influence on the proteins via changes in the organization of the lipid phase of the membrane.

Effect of trimethyllead chloride on slowly activating (SV) channels in red beet (Beta vulgaris L.) taproots

“…In our recent theoretical studies [30], where trimethyllead chloride was used for analysis of the ion current distribution function, it was shown that Met 3 PbCl influences the variance of the open-state ion current but does not alter the probability distribution function of the closed-state ion current. Taking into account our theoretical studies and also the fact that organolead compounds influence model and biological membranes [31][32][33][34][35], we have undertaken systematic studies on the effect of trimethyllead chloride (Met 3 PbCl) on SV channels in vacuoles isolated from red beet (Beta vulgaris L.) taproots.…”

Influence of amphiphilic compounds on membranes.

“…This is strange because their effect on membranes should be considered first in view of the amphiphilic character of the compounds. Our investigations indicated the following harmful effects of the compounds on lipid membranes: disorganisation of monomolecular lipid layers (Trela et al, 1997a;1997b) destabilisation of BLMs (Langner et al, 1998;Sarapuk et al, 2000), of erythrocytes (Kleszczyñska et al, 1997) and of algae (Trela et al, 1997b), effect on phase transitions in lipid layers , effect both on lipids and membrane enzyme proteins (Przestalski et al, 2000). In particular, we have found an effect of a change in membrane polarisation (electric charge) on membrane accessibility of amphiphilic cations of organic tin and lead compounds (Kuczera et al, 1997;Kleszczyñska et al, 1998).…”

“…Compounds containing a metal and organic radical are amphiphilic. They interact with living organisms and exhibit toxic action (Przestalski et al, 2000). Such organic tin and lead compounds are, in general, considerably more toxic than inorganic compounds of the metals.…”

Peptides conformational changes of the erythrocyte membrane induced by organometallic tin compounds

“…Of those only a few concentrate on the possible molecular mechanisms of OTC toxicity. It was been shown, in particular, that OTC compounds reduce the stability of lipid membranes Rozycka-Roszak and Pruchnik, (2001), Chicano et al, (2001), induce hemolysis Kleszczyńska et al, (1997), and alter Na + /K + -ATPase activity Przestalski et al, (2000) activity. One possible mechanism of OTC-protein interaction is the formation of bonds between Sn (IV) atoms and thiol groups Stridh et al, (2001).…”