Figure 2.

STS alters PMP as an early response in HeLa cells. (a) Cells loaded with bisoxonol to follow PMP were exposed to 1 μM STS at the time indicated inducing membrane depolarization (dashed line, n=48), hyperporlarization (dotted line) or a mixed response (solid line), n=28 for both conditions. Once the fluorescence signal has stabilized, Gram was added as depolarization control. Depending whether the PMP finished above or below resting PMP (i.e., PMP before application of STS) were defined either depolarization (D) or hyperpolarization (H), respectively. These records show PMP responses of cells from three different passages, we do not know why the ion channels responding to STS vary among different passages. (b) Cells incubated in either TEA⁺ and 4AP or the combination of TEA⁺, 4AP and FA were exposed to STS were indicated. A mixed response (solid line, n=26) became depolarizing response by the addition of TEA⁺ and 4AP to inhibit K⁺ channels (dotted line, n=12). The combination of all three ion channels inhibitors blocked completely the STS-induced changes in PMP (dashed line, n=14). (c) Average resting PMP and the effect of ion channels inhibitors for cells that respond to STS with either hyperpolarization (white bars) or depolarization (dark bars) depicted as CTL. TEA⁺ and 4AP did not affect resting PMP but inhibited the STS-induced hyperpolarization, particularly for H responses and favored D responses. Notice that the combination of TEA⁺, 4AP and FA-induced hyperpolarization of the resting PMP and totally abolished the STS-induced PMP changes. In this figure, ^*P<0.05 with respect to the corresponding resting PMP. From left to right n=26, 47, 8, 12, 3, 9, 28, 48, 8, 12, 3 and 14 respectively