Tumor Necrosis Factor Alpha Inhibits L-Type Ca²⁺ Channels in Sensitized Guinea Pig Airway Smooth Muscle through ERK 1/2 Pathway

Figure 2

Voltage dependent L-type Ca²⁺ currents were diminished by sensitized guinea pig serum and by TNF-α in guinea pig tracheal myocytes. (a) Similar Ba²⁺ currents, equivalent to Ca²⁺ currents, induced by 10 mV increments were observed in myocytes from nonsensitized (NS) animals grown with fetal bovine serum (FBS) or serum from nonsensitized guinea pigs (Ser-NS). These currents were significantly diminished when myocytes from NS and sensitized (S) animals were grown with serum from sensitized guinea pigs (Ser-S, 10%). This phenomenon was not seen when myocytes from S were grown with FBS ( for each group). (b) Ba²⁺ currents in myocytes from NS grown with FBS showed a decrease when TNF-α was added. These responses were concentration dependent and only the highest (1000 μg/L) produced a significant reduction of this current ( for each group). Insets in each figure represent original recordings. , , and when compared with NS + FBS group. Symbols represent mean ± SEM.

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