ABSTRACT
[3H]-diazepam binds to sites on human granulocyte membranes, with little or no binding to platelets or lymphocytes. These [3H]-diazepam binding sites are of the peripheral type, being strongly inhibited by R05-4864 (Ki = 6.23nM) but only weakly by clonazepam (Ki = 14 microM). Binding of [3H] diazepam at 0 degree is saturable, specific and stereoselective. Scatchard analysis indicates a single class of sites with Bmax of 109 +/- 17f moles per mg of protein and KD of 3.07 +/- 0.53nM. Hill plots of saturation experiments gave straight lines with a mean Hill coefficient of 1.03 +/- 0.014. Binding is time dependent and reversible and it varies linearly with granulocyte protein concentration over the range 0.025-0.300 mg of protein.
Subject(s)
Diazepam/blood , Granulocytes/metabolism , Receptors, GABA-A/analysis , Benzodiazepines/pharmacology , Humans , In Vitro Techniques , TritiumABSTRACT
Monoamine oxidase (MAO) levels in plasma, platelets, lymphocytes and granulocytes have been compared in schizophrenics and controls using three substrates. No significant difference was found between MAO levels in controls and the schizophrenic group as a whole, but platelets and lymphocytes of the latter (tyramine or benzylamine substrate) showed greater variation and in some cases higher values than controls, irrespective of treatment. Schizophrenics who experienced auditory hallucinations had significantly lower MAO levels in lymphocytes and platelets than those who did not.
Subject(s)
Blood Platelets/enzymology , Granulocytes/enzymology , Lymphocytes/enzymology , Monoamine Oxidase/blood , Schizophrenia/enzymology , Adult , Benzylamines , Female , Hallucinations/blood , Hallucinations/enzymology , Humans , Male , Schizophrenia/blood , Serotonin , TyramineABSTRACT
The properties of monoamine oxidase in plasma, platelets, lymphocytes and granulocytes have been studied using cells prepared from a single small (about 20 ml) sample of blood. The three substrates, 5-hydroxytryptamine, tyramine and benzylamine, have been used to obtain a more complete picture of blood monoamine oxidase than was previously possible. Measurement of Michaelis constants, use of selective inhibitors, and activity against the three substrates distinguished three types of activity. The monoamine oxidases in platelets and lymphocytes are very similar, being most active with tyramine or benzylamine as substrate and inhibited by low concentrations of deprenil. The enzymes in plasma and granulocytes are similar in their relatively high activity against 5-hydroxytryptamine and in their inhibition by semicarbazide and cuprizone with tyramine or benzylamine as substrates. They differ in their affinities for 5-hydroxytryptamine and their activity against tyramine. The activity in platelets, plasma, lymphocytes and granulocytes has been measured in a group of 15 normal subjects using three substrates.
