Chain modification of a thiazolidinone prostaglandin isostere has led to the production of 4- [3-[3-[2-( l-hydroxy-cyclohexyl) ethyl]-4-oxo-2-thiazolidinyl] propyl] benzoic acid (5b) which at 1 mg/kg PO in the conscious dog causes a 70% increase in renal blood flow over control values with a duration of action exceeding 5 h. Preliminary testing indicates that 5b has a relatively specific action on the vasculature of the kidney. The enantiomers of 5b have ...