title: Transbilayer transport of a propyltrimethylammonium derivative of diphenylhexatriene (TMAP-DPH) in bovine blood platelets and adrenal chromaffin cells.
abstract: The membrane fluorescent probe N-((4-(6-phenyl-1,3,5-hexatrienyl)phenyl)propyl)trimethylammonium (TMAP-DPH) has an additional three-carbon spacer between the fluorophore and the trimethylammonium substituent of 1-(4-trimethylammoniumphenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH). As a basic study to clarify the transport mechanism of amphiphilic quaternary ammoniums, we observed the characteristics of the transbilayer transport of TMAP-DPH in bovine blood platelets and bovine adrenal chromaffin cells using the albumin extraction method. We compared these inward transport rates with those of TMA-DPH. TMAP-DPH crossed into the cytoplasmic layers of the membranes more slowly than TMA-DPH after rapid binding to the outer halves of the plasma membranes. The transport rate markedly depended on temperature. Time to reach the half-maximal incorporated amount of TMAP-DPH increased threefold accompanied by an increase in the concentration from 0.2 to 1.5 microM. The transport was stimulated significantly by various types of membrane perturbations such as modification of sulfhydryl-groups by N-ethylmaleimide and benzyl alcohol-induced increase in the fluidity of the lipid bilayer. The saturation phenomenon suggested the presence of the regulatory process in the transbilayer transport of TMAP-DPH.
authors.affiliation: Department of Pharmaceutics, Faculty of Pharmaceutical Sciences, Niigata University of Pharmacy and Applied Life Sciences, Kamishin'ei-cho 5-13-2, Niigata 950-2081, Japan. kitagawa@niigata-pharm.ac.jp
authors.forename: Shuji
authors.initials: S
authors.lastname: Kitagawa
authors.forename: Eiichi
authors.initials: E
authors.lastname: Tachikawa
authors.forename: Takashi
authors.initials: T
authors.lastname: Kashimoto
mesh_terms: D000311:Adrenal Glands / Q000166:cytology*; D000818:Animals; D019905:Benzyl Alcohol / Q000494:pharmacology; D001693:Biological Transport, Active; D001792:Blood Platelets / Q000378:metabolism*; D002417:Cattle; D019439:Chromaffin Cells / Q000378:metabolism*; D004161:Diphenylhexatriene / Q000031:analogs & derivatives* / Q000493:pharmacokinetics*; D004305:Dose-Response Relationship, Drug; D005033:Ethylmaleimide / Q000494:pharmacology; D066298:In Vitro Techniques; D008051:Lipid Bilayers / Q000378:metabolism*; D008560:Membrane Fluidity; D000644:Quaternary Ammonium Compounds / Q000493:pharmacokinetics*; D013439:Sulfhydryl Reagents; D013997:Time Factors
chemical_list: D008051:Lipid Bilayers; C474454:N-((4-(6-phenyl-1,3,5-hexatrienyl)phenyl)propyl)trimethylammonium; D000644:Quaternary Ammonium Compounds; D013439:Sulfhydryl Reagents; D004161:Diphenylhexatriene; C033628:1-(4-(trimethylamino)phenyl)-6-phenylhexa-1,3,5-triene; D019905:Benzyl Alcohol; D005033:Ethylmaleimide