It is unknown whether extracellular
calcium may regulate the expression of transient receptor potential canonical type 3 (TRPC3) channels in patients with
chronic kidney disease. Using quantitative in-cell Western assay we compared the expression of
TRPC3 channel protein in monocytes from 20 patients with
chronic kidney disease and 19 age- and sex-matched healthy control subjects. TRPC3 channels were identified by immunoblotting using specific
antibodies and TRPC3
protein was further confirmed by mass spectrometry. We observed a significant increase of
TRPC3 channel protein expression in patients with
chronic kidney disease compared to healthy control subjects (normalized expression, 0.42±0.06 vs. 0.19±0.03; p<0.01). Expression of TRPC3 was significantly inversely correlated with estimated glomerular filtration rates (Spearman r=-0.41) or serum
calcium concentration (Spearman r=-0.34). During a
hemodialysis session serum
calcium concentrations significantly increased, whereas the expression of TRPC3 channels and
calcium influx significantly decreased. In vitro studies confirmed that higher
calcium concentrations but not
magnesium,
barium nor
sodium concentrations significantly decreased TRPC3 expression in human monocytes. This study indicates that reduced extracellular
calcium concentrations up-regulate
TRPC3 channel protein expression in patients with
chronic kidney disease.