8-[(2,6-dimethylbenzyl)amino]-2,3-dimethylimidazo[1,2-a]pyridine-6-carboxylic acid is chemical agent.

Protopine has antiplatelet effects,which is due to inhibition on thromboxane formation and phosphoinositides breakdown and then lead to the decrease of intracellular calcium concentration.

Porcine dynorphin A (1-13) is a potent, endogenous κ opioid receptor agonist and is antinociceptive at physiological concentrations. Exposure to dynorphin A (1-13) causes acute increases in [Ca2+]i in individual neurons similar to increases seen with acute NMDA treatment.