Fig. 1.

Effect of IL-1β on K⁺ channel activity and its abolishment by IL-1ra in cultured human proximal tubule cells. a–c Representative current traces showing acute suppression of channel activity by IL-1β (a), blockade of the suppressive effect by IL-1ra (b), and restoration of channel activity by IL-1ra in the presence of IL-1β (c). Dotted line represents the closed channel level. Short thick horizontal bar on the left of each trace represents the open channel level. The NP _o values calculated from these current traces were 0.75–0.86 for controls, 0 for IL-1β alone, 0.82 for IL-1ra alone, 0.84 for IL-1ra + IL-1β, and 0.68 for IL-1β + IL-1ra. The doses of IL-1β and IL-1ra were 15 pg/ml and 20 ng/ml, respectively. Each trace was obtained from separate cell-attached patches at a V _p of 0 mV. d Summary of the effects of IL-1β on channel activity and its blockade by IL-1ra. From the top, effects of IL-1β (n = 18), IL-1ra (n = 10), IL-1β in the presence of IL-1ra (n = 10), and IL-1ra added to the bath after IL-1β (n = 8). **P < 0.01, significantly different compared with the initial control level