Fig. 4.

Cannabinoid agonist WIN induces increases in [Ca²⁺]_i. WIN produced a transient rise in [Ca²⁺]_i that began within seconds after application (arrows) and returned to baseline within 1 min in a dose-dependent manner for both DRG neurons (A) and F-11 cells (B). Each Ca²⁺ trace represents the mean ± S.E.M. from 25 DRG neurons or 21 F-11 cells measured individually. Error bars are smaller than the corresponding symbols in many cases. Data were acquired at 4-s intervals throughout the entire experiments. C, average peak amplitudes in the [Ca²⁺]_i produced by WIN in both cell types. *, p < 0.05, compared to control (Con) by post hoc Scheffe's tests. D, CB1 receptor antagonist AM251 (AM; 500 nM) inhibited WIN-induced increase in [Ca²⁺]_i, whereas the CB2 receptor antagonist SR144528 (SR; 500 nM) had little effect. AM251 alone had little effect on Ca²⁺ levels. *, p < 0.05 compared to WIN alone, Scheffe's tests. All experiments were conducted in normal DPBS. The dotted line indicates the baseline calcium level.