Fig. 1.

A: Effect of solute concentration on medium viscosity. The viscosity (η) at a given concentration of carbohydrate (expressed as mass fraction, c) was measured in a falling ball viscometer at 20°C as described in methods. B: Solution viscosity (η) inhibits the plasma membrane H⁺-ATPase. The V_max at a given concentration of solute was calculated by measuring the rate of ATP hydrolysis versus ATP concentration and fitting to the Hill equation [eq 2]. The relative V_max (V_max0/V_max) was plotted against the relative viscosity (η/η0). Both, η0 and V_max0 are the solution viscosity and the maximum velocity respectively in the absence of the viscosogenic agent: Glycerol ○; Trehalose ; Sucrose □.