an intracellular calcium antagonist; protein kinase C inhibitor.

C₂₂H₃₇NO₅ .HCl ‚ synthetic.

reduces Ca²⁺ influx and efflux in guinea pig ileum‚ and caffeine-induced release of Ca2+ from sarcoplasmic reticulum vesicles [2].


In quin2-loaded human platelets‚ has a weak inhibitory effect on Ca²⁺ movements but a more effective inhibition of secretion‚ including that evoked by TPA‚ a direct activator of protein kinase C [2].

1. Scharff et al., "Effect of trifluoperazine, compound 48/80, TMB-8 and verapamil on the rate of calmodulin binding to erythrocyte Ca⁺⁺ - ATPase." Biochem. Biophys. Acta (1984). 772:29-36
2. Simpson et al., "TMB-8 inhibits secretion evoked by phorbol ester at basal cytoplasmic free calcium in quin2-loaded platelets much more effectively than it inhibits thrombin-induced calcium mobilisation." FEBS Letters (1984). 176(1):139-143
3. Chiou et al., "Cobra venom cardiotoxin (cytotoxin) isoforms and neurotoxin: comparative potency of protein kinase C inhibition and cancer cell cytotoxicity and mode of enzyme inhibition." Biochemistry 1993 53:279-285
4. Yamada et al., "Intracellular Ca²⁺ antagonist TMB-8 blocks catecholamine secretion evoked by caffeine and acetylcholine from perfused cat adrenal glands in the absence of extracellular Ca²⁺." Neurosc. Lett. (1988). 90:338-342