(S)- (-)-Bay K 8644

(S)-(-)-Bay K 8644 is a L-type Ca channel agonist while R-(+)-Bay K8644 is an antagonist. (S)-(-)-Bay K 8644 causes a left shift in the Q1 (activation charge) vs. V activation curve at nanomolar concentrations in guinea-pig ventricular myocytes. The (−)-enantiomer has vasoconstricting and positive inotropic properties. (−)-Bay K 8644 also enhances the force of contraction and prolongs the action potential duration measured at 50% of repolarization in guinea-pig papillary muscles at normal resting potential. (−)-S-BAY K 8644 impairs rotarod and motor activity with an ED₅₀ value of 0.5 mg/kg in mice. It enables reprogramming of Oct4/Klf4-transduced mouse embryonic fibroblasts.