Proadrenomedullin (1-20), human is a potent hypotensive and catecholamine release-inhibitory peptide released from chromaffin cells with an IC50 of ~350 nM for catecholamine secretion in PC12 pheochromocytoma cells, acting in a noncompetitive manner specifically at the nicotinic cholinergic receptor[1].
[1]. Mahata M, et al. Proadrenomedullin N-terminal 20 peptide: minimal active region to regulate nicotinic receptors. Hypertension. 1998 Nov;32(5):907-16.