Methanandamide

The ratiometric fluorescent dye Fura-2 was purchased from Molecular Probes (Eugene, OR, USA), dissolved in dimethylsulfoxide at 1 mM, and further diluted in KHB containing 0.25 mM Ca²⁺ to a working concentration of 5 μM as described [17 (link)]. The aminoalkylindole agonist of CB_1/2 cannabinoid receptors WIN55212-2 (5 μM) [6 (link)], the prototype bicyclic non-selective CB_1/2R agonist CP55940 (5 μM) [6 (link)], and the stable chiral analog of anandamide, a CB₁R partial agonist, methanandamide (5 μM) [6 (link)], were from Cayman Chemical Co, (Ann Arbor, MI, USA). Receptor antagonists used include the blocker of CaSR, NPS2314 (3 μM) [18 (link)], the selective store-operated calcium (SOC) channel inhibitor N-propargyl-nitrendipine (MRS1845, 10 μM) [19 (link)], the CB₁R antagonist SR141716 (1 μM) [6 (link)], and the non CB₁/CB₂ receptor blocker O-1918 (10 μM) [20 (link)], all from Cayman Chemical Co, (Ann Arbor, MI, USA). The cannabinoid compounds were stored at −20 °C as 10 mM stock solutions in ethanol. Immediately before use, an aliquot of drug stocks was air-dried and re-suspended in 0.25 mM Ca²⁺ KHB. All other chemical reagents were from Sigma-Aldrich Chemical Co. (St. Louis, MO, USA).