Figure 2.

(A) Triphasic effect of a high concentration of NaHS (10⁻² mol·L⁻¹at the serosal side; arrow) on short-circuit current (Isc). The three main phases of the Isc response are labelled (1) to (3); the inconsistent early fall in Isc, which was not further analysed, is marked (). Values are means (symbols) ± SEM (lines), n= 8. (B) Desensitization induced by repeated administration of NaHS (10⁻³ mol·L⁻¹ at the serosal side, arrows). The line interruptions are caused by omission of current artefacts induced by washing the serosal compartment three times with 5× the chamber volume, before the next administration of NaHS followed. Typical trace of eight experiments with similar results. On average, the first administration evoked an increase in Isc above baseline (ΔIsc) of 0.86 ± 0.39 µEq·h⁻¹·cm⁻², the second administration of 0.23 ± 0.07 µEq·h⁻¹·cm⁻²and the third of 0.18 ± 0.02 µEq·h⁻¹·cm⁻²(n= 8). (C) Effect of NaHS (10⁻² mol·L⁻¹at the serosal side; arrow) in the presence of tetrodotoxin (TTX; 10⁻⁶ mol·L⁻¹ at the serosal side; solid bar). Values are means (symbols) ± SEM (lines), n= 6. For statistics, see Table 1.