Effects of four different GABAB receptor antagonists (CGP35348 100 μmol kg−1, CGP36742 7–112 μmol kg−1, CGP62349 7–700 nmol kg−1 and CGP54626 70 nmol–3 μmol kg−1) on the baclofen (7 μmol kg−1 i.v.)-induced change in LOS contraction after vagal stimulation (PVS, 0.5 ms pulses, 20 V, 5 and 10 Hz, 5 s duration). The increase in response after baclofen was unchanged by CGP35348 or CGP36742, but was potently antagonized by CGP62349 or CGP54626 (mean ED50s 37 and 100 nmol kg−1 respectively).