Figure 1.

Inhibition of nerve depolarisation by cannabinoids. The nonselective cannabinoid agonist CP 55940 inhibits (a) capsaicin (1 μM), (b) PGE₂ (1 μM) and (c) hypertonic saline (2%)-induced depolarisation of the guinea-pig vagus nerve. Similarly, the CB₂-selective receptor agonist JWH 133 inhibits (d) capsaicin (1 μM), (e) PGE₂ (1 μM) and (f) hypertonic saline (2%)-induced depolarisation of the guinea-pig vagus nerve. Nerve depolarisation responses were expressed as absolute values in mV depolarisation before and after drug additions, and then expressed a percentage change. The data were subjected to a paired two-tailed t-test, since the response to a stimulant was measured before and after drug treatment within the same nerve. ^*P<0.05, ^**P<0.01 and ^***P<0.001 denote statistical significance. Values are presented as the mean±s.e.m. percentage change of n=4 determinations. pD₂ values (−log of the EC₅₀ defined as the concentration of drug required to elicit 50% of the maximum response) and statistical significance were calculated using ‘GraphPad Instat™' (© GraphPad Software).