Summary
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 μg/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 increasedto 165 ± 14% ofreference (n = 16, P < 0.005). LDL-induced effects on ifo-current could be mimicked by application of the calcium ionophore A 23187 (1 μmol/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 μg/ml, 5–15 min) produced no significant effect on the membrane currents under investigation.
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Correspondence to U. Borchard at the above address
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Berger, F., Borchard, U., Hafner, D. et al. Activation of membrane outward currents by human low density lipoprotein in mouse peritoneal macrophages. Naunyn-Schmiedeberg's Arch Pharmacol 348, 207–212 (1993). https://doi.org/10.1007/BF00164800
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DOI: https://doi.org/10.1007/BF00164800