Bay-K-8644 (S)-(-)- is primarily used in research settings as a calcium channel agonist, specifically targeting L-type calcium channels. It is employed to study the role of calcium influx in various cellular processes, such as muscle contraction, neurotransmitter release, and hormone secretion. In cardiovascular research, it helps investigate the mechanisms of vasoconstriction and cardiac muscle function. Additionally, it is utilized in neuroscience to explore calcium-dependent signaling pathways in neurons and their implications in conditions like epilepsy and neurodegenerative diseases. Its selective action on L-type channels makes it a valuable tool for understanding calcium's role in physiological and pathological states.