Fig. 3
Functional KCa1.1 β3b subunits are present on the plasma membrane of fibroblast-like synoviocytes from patients with rheumatoid arthritis (RA-FLS). a Representative traces of whole-cell KCa1.1 currents elicited by 140-mV pulses for 200 milliseconds with 5 μM Ca2+ in the internal solution before (control) and after applying 2 μM paxilline (Pax), 100 nM charybdotoxin (ChTX), 30 μM arachidonic acid (AA), or 75 μM lithocholic acid (LCA). The two top traces are representative of ≥92 % of cells tested; the two middle traces are representative of approximately 70 % of cells tested; and the two bottom traces are representative of the other approximately 30 % of cells tested. b Peak KCa1.1 currents after different treatments normalized to the control levels. Mean ± SEM; n = 5 different donors. c Representative Western blot from a gel loaded with proteins from one RA-FLS donor or a rat testis extract. Different lanes were probed with antibodies against all splice variants of KCa1.1 β3 (pan-β3) or against KCa1.1 β3a, βc, βd, and βe only (top), and intensity of KCa1.1 β3 protein bands was normalized to actin expression levels in RA-FLS. Mean ± SEM; n = 6 different donors. d Activation kinetics (τAct) of RA-FLS K+ currents. Each symbol on the scatterplot represents a different cell. n = 5 different donors; **p ≤ 0.01, ***p ≤ 0.001