thromboxane-b2 and exaprolol

Lipophilic exaprolol and hydrophilic atenolol differ in their interaction with mast cell membranes. Exaprolol, as compared with atenolol, significantly decreased 32P incorporation into, but increased arachidonic acid liberation from, membrane phospholipids. Moreover, exaprolol significantly decreased phosphate incorporation in compound 48/80 and ConA-PS treated cells and decreased thromboxane formation in stimulated cells. On the other hand, atenolol decreased significantly only arachidonate liberation from stimulated mast cells. These results corroborate to some extent the effect of exaprolol and atenolol on histamine liberation which correlates with their membrane perturbing properties.

Topics: Adrenergic beta-Antagonists; Animals; Arachidonic Acid; Arachidonic Acids; Atenolol; Cell Membrane; Concanavalin A; Male; Mast Cells; Membrane Lipids; p-Methoxy-N-methylphenethylamine; Phosphates; Phosphatidylserines; Phospholipids; Phosphorus Radioisotopes; Propanolamines; Rats; Rats, Inbred Strains; Thromboxane B2

Chloroquine liberated a relatively low amount of histamine from isolated rat mast cells. In a dose-dependent way, this drug inhibited histamine liberation from mast cells stimulated with compound 48/80, A23187, concanavalin A plus phosphatidylserine (Con A + PS) and abolished histamine liberation induced by exaprolol. The degranulation was decreased in cells stimulated with 48/80, Con A + PS and exaprolol. Chloroquine significantly inhibited the formation of thromboxane B2 in mast cells stimulated with 48/80, Con A + PS and A23187. We assume that chloroquine interferes with mast cells at a plasmic membrane site as well as intracellularly.

Topics: Adrenergic beta-Antagonists; Animals; Calcimycin; Chloroquine; Concanavalin A; Dose-Response Relationship, Drug; Histamine Release; Male; Mast Cells; p-Methoxy-N-methylphenethylamine; Phosphatidylserines; Propanolamines; Rats; Rats, Inbred Strains; Thromboxane B2