Human serum albumin (HSA) decreases prostaglandin A1 (PGA1) metabolism.

PGA₁ was incubated with rabbit renal cortical homogenates containing HSA (0–4.5%). The ability of this tissue to readily metabolize PGA₁ progressively decreased with increasing HSA levels in the incubates The rate of disappearance of ³H-PGA₁ was twice as rapid in rats treated with salicylic acid (S. A.) in comparison to control animals; since only 30% of the injected radioactivity was bound to the plasma of the S.A. treated rats, as compared to 90% bound to control plasma, an association may exist between the degree of binding of ³H-PGA₁ and its rate of clearance. The studies indicate that PGA₁ interaction with HSA decreases its metabolism $\text{in vitro}$, and slows down its clearance $\text{in vivo}$, implicating HSA as a possible factor in prostaglandins metabolism $\text{in vivo}$.