Relative NO produced in haemocytes from schistosome-susceptible (S) and schistosome-resistant (R) B. glabrata strains in the presence and absence of 20 μg/ml ESPs over time. Equal volumes (100 μl per well) of diluted haemolymph (A), or an equal number of haemocytes (3 × 103 cells per well) (B) from each snail strain were used in NO assays. Mean relative fluorescence from a single pool of haemolymph (± SEM, n = 4) is shown for each time point as a proportion of background fluorescence (no DAF-FM diacetate, indicated by the dotted line). Data shown are from one assay and are representative of three different assays conducted on separate days. *P ≤ 0.05 and **P ≤ 0.01 for differences in mean fluorescence values between treatments at 2 h.