A potent and effective calcium-sensitive opener of maxi-K potassium channels (maxi-K) with EC50 of 392 nM at -48.4 mV in HEK293 isolated outside-out membrane patches.

Apamin (Apamine) is an 18 amino acid peptide neurotoxin found in apitoxin (bee venom), is known as a specifically selective blocker of Ca2+-activated K+ (SK) channels and exhibits anti-inflammatory and anti-fibrotic activity. Apamin is a bee venom component and is strongly basic in nature.

OR-1896 is the active metabolite of Levosimendan, a highly specific phosphodiesterase (PDE III) inhibitor, a vasodilator with partial anti-inflammatory properties that produces vasodilation in different types of blood vessels through activation of ATP-sensitive (KATP) and other potassium channels.