The physiological effects of synthetic replicates of the nematode FaRPs,
AF1 (KNEFIRFamide), AF2
(KHEYLRFamide), PF1 (SDPNFLRFamide), PF2 (SADPNFLRFamide), AF8/PF3
(KSAYMRFamide) and PF4
(KPNFIRFamide) were examined on muscle preparations of the liver fluke, Fasciola
hepatica. Changes in contractility
following the addition of the test compound were recorded using a photo-optic
transducer system. Unlike the varied
effects these peptides have on nematode somatic musculature, all were found to
induce excitatory responses in the muscle
activity of F. hepatica. While qualitative effects of the nematode
peptides were similar in that they induced increases in
both the amplitude and frequency of F. hepatica muscle contractions,
they varied considerably in the potency of their
excitatory effects. The threshold activity for each peptide was as follows:
10 μM, PF1 and PF2; 3 μM, AF1 and PF3; 1 μM,
AF2; and 30 nM, PF4. The results demonstrate, for the first time,
the cross-phyla activity of nematode neuropeptides on
the neuromuscular activity of a trematode.