title: Activation of membrane outward currents by human low density lipoprotein in mouse peritoneal macrophages.
abstract: The aim of the present study was to search for electrophysiological effects of human lipoproteins on membrane currents in mouse peritoneal macrophages which had been cultured for 5 to 20 days. Whole-cell currents were recorded by using a voltage-clamp technique. Low density lipoprotein (LDL, 100 micrograms/ml) increased a slowly activating nonspecific cation current (iso) in the positive potential range to 244 +/- 23% of the reference (test potential + 55 mV, n = 13, P < 0.005). Augmentation of current resulted out of a negative shift of the activation curve along the voltage axis (-22 mV) and an increase of maximally available current. Furthermore, LDL increased a rapidly activating outward current (ifo) at test potentials positive to the potassium equilibrium potential. At +55 mV ifo-amplitude increased to 165 +/- 14% of reference (n = 16, P < 0.005). LDL-induced effects on ifo-current could be mimicked by application of the calcium ionophore A 23,187 (1 mumol/l) which led to an increase of ifo-current to 161 +/- 25% of the reference (test potential +55 mV, n = 11, P < 0.005). Acetylated-LDL (100 micrograms/ml, 5-15 min) produced no significant effect on the membrane currents under investigation.
authors.affiliation: Institut für Pharmakologie, Universität Düsseldorf, Germany.
authors.forename: F
authors.initials: F
authors.lastname: Berger
authors.forename: U
authors.initials: U
authors.lastname: Borchard
authors.forename: D
authors.initials: D
authors.lastname: Hafner
authors.forename: T
authors.initials: T
authors.lastname: Weis
mesh_terms: D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D002478:Cells, Cultured; D007473:Ion Channels / Q000502:physiology; D008077:Lipoproteins, LDL / Q000494:pharmacology*; D008264:Macrophages / Q000502:physiology*; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D051379:Mice; D010529:Peritoneal Cavity / Q000166:cytology
chemical_list: D007473:Ion Channels; D008077:Lipoproteins, LDL; C032629:acetyl-LDL; D000001:Calcimycin