Effect of amphotericin B on intracellular calcium levels in cultured glomerular mesangial cells.
Amphotericin B induces a reduction in the glomerular filtration rate due, in part, to a decrease in the glomerular capillary ultrafiltration coefficient (Kf), possibly resulting from mesangial cell contraction. The present study has examined the effect of amphotericin B on intracellular free calcium concentrations ([Ca2+]i) in cultured glomerular mesangial cells, using the fluorescent probe, fura-2. Under control conditions, amphotericin B caused a concentration-dependent increase in [Ca2+]i with a 231 +/- 52 nM increase at a concentration of 10(-6) M. This increase was almost completely inhibited when Ca2+ ions were omitted from the cell medium (an increase of 34 +/- 7 nM, P less than 0.0001). Replacement of extracellular Na+ ions with N-methylglucamine caused a marked inhibition of the amphotericin B-induced rise in [Ca2+]i (28 +/- 5 nM, P less than 0.0001). Diltiazem (20 microM) also suppressed the rise in [Ca2+]i seen with amphotericin B (36 +/- 6 nM, P less than 0.0001). In contrast, theophylline (20 microM) enhanced the response to amphotericin B (351 +/- 51 nM rise, P less than 0.001). The results suggest that amphotericin B-induced mesangial cell contraction is secondary to Ca2+ entry from the extracellular space through voltage-dependent calcium channels. The dependence of the response on extracellular Na+ suggests that Na+ entry induces depolarization of the membrane and opening of voltage-dependent calcium channels.
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Center for Clinical Pharmacology, University of Pittsburgh School of Medicine, PA 15261.
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D000666:Amphotericin B / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D003470:Culture Media; D004110:Diltiazem / Q000494:pharmacology; D016257:Fura-2; D005920:Glomerular Mesangium / Q000187:drug effects* / Q000378:metabolism; D008536:Meglumine / Q000494:pharmacology; D012964:Sodium / Q000378:metabolism; D013806:Theophylline / Q000494:pharmacology
D003470:Culture Media; D008536:Meglumine; D000666:Amphotericin B; D012964:Sodium; D013806:Theophylline; D004110:Diltiazem; D002118:Calcium; D016257:Fura-2