Leishmania amazonensis Infection Induces Changes in the Electrophysiological Properties of Macrophage-like Cells

Abstract

Whole cell patch-clamp recordings were used to study the electrical properties of the macrophage-like cell line J774.1, after infection with Leishmania amazonensis. Infection induced a significant increase in cell size and membrane capacitance, suggesting that parasite invasion leads to the addition of plasma membrane to the host cell. By 24 hr after infection, the host cell membrane potential was significantly more hyperpolarized than control cells, and this difference remained for the subsequent 72 hr post-infection. The hyperpolarization was paralleled by an increase in the density of inward rectifying K(+) currents. The shape of the conductance vs. voltage curve, the kinetic properties and the pharmacological profile of these currents were not significantly altered by infection. These results suggest that infection by L. amazonensis causes an increase in the number of functional inward rectifying K(+) channels, leading to hyperpolarization of the host cell membrane.

Leishmania (Viannia) braziliensis growth in vitro culture relies more on folic acid availability than Leihsmania (Leishmania) amazonensis

“…Parasites were cultured as previously described (Forero et al 1999). L. (V.) braziliensis (HOM/BR/75M2903) and L. (L.) amazonensis (FLA/BR/67/PH8) isolates, kindly donated by Dr Nancy Gore Saravia (Cideim, Cali, Colombia) were used in the present study.…”

Electrical Membrane Properties in the Model Leishmania-Macrophage

“…I OUT and I KIR have similar amplitudes after 24 hours post-adherence (Gallin & Sheehy, 1985), but after 48 hours the situation reverses, with predominant I KIR and negligible I OUT (McKinney & Gallin, 1990). We have therefore controlled for time of adherence onto glass in some of our experiments to guarantee similar amplitudes for I OUT and I KIR (Forero et al, 1999;Camacho et al, 2008;Quintana et al, 2010).…”

“…Macrophage passive electrical membrane properties have been recorded in primary macrophages of mouse (Buisman et al, 1988;Vicente et al, 2003), man (Gallin & Gallin, 1977;Holevinsky & Nelson, 1998), various mouse (Randriamampita & Trautmann, 1987;Buisman et al, 1988;Holevinsky & Nelson, 1998;Gallin, 1991;Forero et al, 1999;Camacho et al, 2008;Quintana et al, 2010;Villalonga et al, 2010) and human (McCann et al, 1987) cell lines. Differences between some measurements of electrophysiological parameters may be related to cell culture conditions, though some authors argue that they represent genuine innate characteristics of currents expressed by macrophages (Randriamampita & Trautmann, 1987).…”

“…Differences between some measurements of electrophysiological parameters may be related to cell culture conditions, though some authors argue that they represent genuine innate characteristics of currents expressed by macrophages (Randriamampita & Trautmann, 1987). Several studies support this hypothesis (Randriamampita & Trautmann, 1987;McKinney & Gallin, 1990;Forero et al, 1999;Camacho et al, 2008). In this view, variations in characterization are explained by differences in the ionic solutions used and the corresponding change to the Nernst equilibrium and the electrochemical force imposed on each ion, and of course by differences in the ion channel populations expressed (Vicente et al, 2006;Villalonga et al, 2007;Vicente et al, 2008).…”

“…The lipid bilayer of the cell membrane can be modelled as a capacitor of two parallel conducting plates separated by a dielectric, so changes in Cm reflect direct changes in membrane area. Cm varies with postadherence time (McKinney & Gallin, 1990) and Leishmania amazonensis post-infection time (Forero et al, 1999;Camacho et al, 2008;Quintana et al, 2010). J774.A1 cells exposed to cytochrome C to induce apoptosis are smaller than control cells, but have a similar Cm (Clavijo et al, 2009) suggesting loss of volume without decrease in surface area.…”