PD 145305 is primarily used in research settings to study the role of endothelin receptors in various physiological processes. It acts as a selective endothelin B (ETB) receptor antagonist, making it a valuable tool for investigating the function of ETB receptors in vascular and non-vascular tissues. Researchers utilize it to explore its effects on blood pressure regulation, vascular tone, and pulmonary hypertension. Additionally, it is employed in studies examining the involvement of ETB receptors in renal function, fibrosis, and cancer progression. Its specificity helps in understanding the distinct roles of endothelin receptor subtypes in disease mechanisms and potential therapeutic targets.