Figure 5.

Mercury inhibition of osmotic water transport in TP-enriched vesicles. (A) Dose dependence of inhibition. Vesicles were preincubated at room temperature for 5 min at the indicated HgCl₂ concentration; P_f values were measured at 20°C in the presence of an 80 mosmol⋅kg⁻¹ mannitol gradient and were reported to the P_f value measured in control untreated vesicles. (B) Reversion of mercury inhibition by a reducing agent. Top curve, untreated control (k = 43.9 s⁻¹); middle curve, after exposure for 5 min to 1 mM HgCl₂ and for 15 min with the addition of 10 mM 2-mercaptoethanol (k = 31.5 s⁻¹); bottom curve, after exposure for 5 min to 1 mM HgCl₂ (k = 4.2 s⁻¹). Note that the slowly decaying plateau of the top and middle curves may indicate a slight permeability of the TP vesicles to mannitol in this experiment.