Effects of halothane on transport of 5-hydroxytryptamine by platelet membranes.
Na+-dependent uptake of 5-HT (5-hydroxytryptamine) into plasma membrane vesicles derived from bovine blood platelets and ATP-dependent 5-HT uptake into storage vesicles in platelet lysates were measured. Na+-dependent uptake was temperature-dependent, inhibited by imipramine and exhibited Michaelis-Menten kinetics (apparent Km, 0.12 +/- 0.02 microM; Vmax. 559 +/- 54 pmol/min per mg of protein. Halothane had no effect on Na+-dependent transport of 5-HT in plasma-membrane vesicles. ATP-dependent 5-HT transport into storage granules also exhibited Michaelis-Menten kinetics (apparent Km 0.34 +/- 0.03 microM; Vmax. 34.3 +/- 1.7 pmol/min per mg of protein) and was inhibited by noradrenaline (norepinephrine), but not by imipramine. Exposure of the granules to halothane resulted in a progressive decrease in Vmax. The results demonstrate a possible site for disruption of platelet function by anaesthetics.
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism*; D001798:Blood Proteins / Q000378:metabolism; D002417:Cattle; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D006221:Halothane / Q000494:pharmacology*; D007700:Kinetics; D012701:Serotonin / Q000097:blood*
D001798:Blood Proteins; D012701:Serotonin; D000255:Adenosine Triphosphate; D006221:Halothane