title: Accumulation of gentamicin by Staphylococcus aureus: the role of the transmembrane electrical potential.
abstract: Accumulation of gentamicin by gentamicin-susceptible Staphylococcus aureus was examined by using the ionophorous antibiotic, valinomycin and the protontranslocating ATPase inhibitor N,N'-dicyclohexylcarbodiimide. The effects of these inhibitors on the transmembrane electrical potential (delta psi) were determined by measuring the equilibrium distribution of the tetraphenylphosphonium ion. The results indicate a direct correlation between delta psi and the extent of gentamicin uptake. However, under conditions where a significant delta psi existed across the plasma membrane, uptake of gentamicin was negligible. A threshold delta psi may thus be required to initiate gentamicin uptake. The proposed threshold delta psi appears to vary depending upon the external concentration of gentamicin.
mesh_terms: D004024:Dicyclohexylcarbodiimide / Q000494:pharmacology; D005839:Gentamicins / Q000378:metabolism*; D008564:Membrane Potentials; D009550:Nigericin / Q000494:pharmacology; D009861:Onium Compounds / Q000378:metabolism; D009943:Organophosphorus Compounds / Q000378:metabolism; D011189:Potassium Chloride / Q000494:pharmacology; D013211:Staphylococcus aureus / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D013997:Time Factors; D014634:Valinomycin / Q000494:pharmacology
chemical_list: D005839:Gentamicins; D009861:Onium Compounds; D009943:Organophosphorus Compounds; D014634:Valinomycin; D004024:Dicyclohexylcarbodiimide; D011189:Potassium Chloride; D009550:Nigericin; C013289:tetraphenylphosphonium