title: Pentobarbitone inhibition of catecholamine secretion.
abstract: 1. The perfused isolated cow adrenal gland was used to investigate the effect of barbituric acid, phenobarbitone and pentobarbitone on catecholamine secretion.2. Pentobarbitone reduced catecholamine secretion induced by a number of drugs which cause exocytosis. The concentration of pentobarbitone which caused a 50% inhibition of catecholamine secretion was for acetylcholine 5.6 x 10(-5)M, for carbachol 6.3 x 10(-5)M, for histamine 1.6 x 10(-4)M, for (+)-amphetamine 4.4 x 10(-5)M and for potassium chloride 1.5 x 10(-4)M. The degree of inhibition by pentobarbitone was not dependent on the concentration of the secretagogue.3. Pentobarbitone (up to 10(-3)M) did not inhibit the catecholamine release that was induced by acetyldehyde or by calcium chloride; it inhibited slightly (34%) the catecholamine secretion induced by tyramine.4. Catecholamine release induced by carbachol was also inhibited by phenobarbitone (50% inhibition at 2.8 x 10(-4)M (n=7)) but was unaffected by barbituric acid.5. Pentobarbitone had no effect on spontaneous or on (+)-amphetamine- or tyramine-induced release of catecholamines from isolated chromaffin vesicles of cow adrenal medulla.6. It is concluded that pentobarbitone inhibits catecholamine release by preventing a configurational change in the structure of the membrane of the chromaffin cell which is a necessary link between receptor activation and catecholamine release.
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000313:Adrenal Medulla / Q000187:drug effects; D000661:Amphetamine / Q000494:pharmacology; D000818:Animals; D001463:Barbiturates / Q000494:pharmacology; D002122:Calcium Chloride / Q000494:pharmacology; D002217:Carbachol / Q000494:pharmacology; D002395:Catecholamines / Q000378:metabolism*; D002417:Cattle; D003594:Cytoplasmic Granules / Q000032:analysis / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005089:Exocytosis / Q000187:drug effects; D006632:Histamine / Q000494:pharmacology; D066298:In Vitro Techniques; D008968:Molecular Conformation; D010424:Pentobarbital / Q000008:administration & dosage / Q000494:pharmacology*; D010477:Perfusion; D010634:Phenobarbital / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology; D014439:Tyramine / Q000494:pharmacology
chemical_list: D001463:Barbiturates; D002395:Catecholamines; D011189:Potassium Chloride; D006632:Histamine; D002217:Carbachol; D000661:Amphetamine; D010424:Pentobarbital; D002122:Calcium Chloride; D000109:Acetylcholine; D014439:Tyramine; D010634:Phenobarbital