the blocking effects of guanethidine on electrically induced , neurally mediated , contractions of the guinea pig vas deferens in vitro could be markedly antagonized by the bee venom polypeptide apamin ( 20-60 nm ) , by 0.1 mm methylene blue , and ( less regularly ) by 0.1-0.15 mm quinine , three substances known to inhibit calcium-activated potassium conductance in a variety of cells .
C0004920
bee venom
C0003521
apamin