In vitro binding of inorganic mercury to the plasma membrane of rat platelet affects Na+-K+-Atpase activity and platelet aggregation.
Hg2+ binding to ouabain-sensitive Na+-K+-ATPase of rat platelet membrane was specific with a Ka of 1.3 x 10(9) moles and Bmax of 3.8 nmoles/mg protein. The binding of mercury to Na+-K+-ATPase also inhibits the enzyme significantly (P < 0.001), which is greater than its ouabain sensitivity. Further in the cytosol of washed platelets conjugation of reduced glutathione (GSH) to Hg2+ is correlated dose dependently (25, 50 and 100 pmoles) to enhanced GSH-S-transferase (GST) activity. It may be concluded from the present in vitro experiments that mercury binds specifically to thiol groups present in the platelet membrane Na+-K+-ATPase, inhibits the enzyme and induces changes in platelet function, namely, platelet aggregation by interfering with the sodium pump.
Kumar
S Vinaya
SV
Environmental Toxicology Laboratory, Department of Zoology, Visva Bharati University, Santiniketan, India.
Maitra
Sudipta
S
Bhattacharya
Shelley
S
D000818:Animals; D001665:Binding Sites; D001792:Blood Platelets / Q000187:drug effects* / Q000502:physiology*; D002462:Cell Membrane / Q000378:metabolism; D005978:Glutathione / Q000097:blood; D005982:Glutathione Transferase / Q000097:blood; D066298:In Vitro Techniques; D007700:Kinetics; D008297:Male; D008628:Mercury / Q000097:blood* / Q000633:toxicity*; D010042:Ouabain / Q000494:pharmacology; D010974:Platelet Aggregation / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors* / Q000097:blood; D013438:Sulfhydryl Compounds / Q000097:blood
D013438:Sulfhydryl Compounds; D010042:Ouabain; D005982:Glutathione Transferase; D000254:Sodium-Potassium-Exchanging ATPase; D008628:Mercury; D005978:Glutathione