An increase in tubular fluid flow rate (TFF) stimulates Na reabsorption and K secretion in the cortical collecting duct (CCD) and subjects cells therein to biomechanical forces including fluid shear stress (FSS) and circumferential stretch (CS). Intracellular mitogen activated protein kinase (MAPK) and extracellular autocrine/paracrine prostaglandin E2 (PGE2) signaling regulate cation transport in the CCD and, at least in other systems, are effected by biomechanical forces. We hypothesized that FSS and CS differentially effect MAPK signaling and PGE2 release to modulate cation transport in the CCD. To validate that CS is a physiologic force in vivo, we applied the intravital microscopic approach to rodent kidneys in vivo to show that saline or furosemide injection led to a 46.5±2.0% or 170±32% increase, respectively, in distal tubular diameter. Next, murine CCD (mpkCCD) cells were grown on glass or silicone coated with collagen type IV and subjected to 0 or 0.4 dynes/cm2 of FSS or 10% CS, respectively, forces chosen based on prior biomechanical modeling of ex vivo microperfused CCDs. Cells exposed to FSS expressed a ~2-fold greater abundance of phospho(p)-ERK and p-p38 vs. static cells, while CS did not alter p-p38 and p-ERK expression compared to unstretched controls. FSS induced whereas CS reduced PGE2 release by ~40%. In conclusion, FSS and CS differentially effect ERK and p38 activation and PGE2 release in a cell culture model of the CD. We speculate that TFF differentially regulates biomechanical signaling and, in turn, cation transport in the CCD.