Figure 4.

Effect of J-113397 (3 mg kg⁻¹), a NOP receptor antagonist, on the inhibitory effect of nociceptin (30 μg kg⁻¹). Guinea-pigs were pretreated with atropine (3 mg kg⁻¹), propranolol (1 mg kg⁻¹) and phosphoramidon (1 mg kg⁻¹). J-113397 was administered 10 min before nociceptin. Data are expressed as mean±s.e.m., n=3–5 per group. ^#P<0.01 vs −HCl, ^*P<0.05 vs +HCl.