Fig. 2.

Effect of morphine and/or PL017 on [Ca²⁺]_i in individual type 1 astrocytes (a–e). Morphine (1 μM) (a), or the selective μ opioid receptor agonist PL017 (b), increased [Ca²⁺]_i in some astrocytes, while naloxone pretreatment prevented PL017-induced increases in [Ca²⁺]_i (c). Morphine and PL017 increased [Ca²⁺]_i in the same cells (d). PL017 treatment increased [Ca²⁺]_i in the absence of extracellular Ca²⁺ (0 [Ca²⁺]_o and 1 mM EGTA) in some cells (e). Drugs were added at 100 nM concentrations, except where noted. Responsive astrocyte (------), non-responsive astrocyte (-------). The scale is identical in a–b, and in c,d–e.