Table 1

Inhibitory effect of various compounds on the initial uptake of14C-SA by liposomes

InhibitorRelative Uptake
% of control
Control100
Salicylic acid19.77  ± 0.47
p-Hydroxybenzoic acid55.70  ± 1.71
m-Hydroxybenzoic acid71.29  ± 1.50
Benzoic acid23.61  ± 1.59
Nicotinic acid62.33  ± 0.42
Acetic acid32.12  ± 2.66
Valproic acid23.50  ± 2.37
l-Lactic acid98.83  ± 1.09
d-Lactic acid99.56  ± 3.71
Phthalic acid92.74  ± 7.18
Sulfanilic acid97.55  ± 3.11
Benzenesulfonic acid97.20  ± 6.99

Liposomal uptake of 14C-SA was measured in the presence of pH gradient across the liposomal membrane ([pH]in = 7.5, [pH]out = 5.8). The concentration of each inhibitor in the extraliposomal solution was 1 mM. Results are expressed as the mean ± S.E. of four experiments.