Trequinsin hydrochloride is primarily used in research settings to study its effects as a potent inhibitor of phosphodiesterase. Its application is significant in exploring cardiovascular diseases, as it helps in understanding the regulation of cyclic nucleotide signaling pathways. Researchers utilize it to investigate potential therapeutic strategies for conditions like hypertension and heart failure by examining its vasodilatory and antiplatelet effects. Additionally, it serves as a tool in pharmacological studies to assess its impact on smooth muscle relaxation and cellular processes influenced by cyclic AMP and cyclic GMP levels.