SHEAR STRESS-INDUCED RELEASE OF PGE(2) AND PGI(2) BY VASCULAR SMOOTH-MUSCLE CELLS

This study addresses the direct effect of fluid how shear stress on pr oduction of the vascular mediators, PGE(2) and PGI(2) by vascular smoo th muscle cells (SMC). Results indicate that shear stress increases PG E(2) and PGI(2) release in SMC. The production patterns, however, diff er between PGE(2) and PGI(2). For PGE(2), the rate of production is mo derate for the first three hours after the onset of shear stress, then dramatically increases between the fourth and fifth hours, returning to basal levels in the sixth hour. On the other hand, the rate for PGI (2), production is maximal right after the onset of shear and remains elevated for the first three hours. The rate then plateaus and remains at a moderate level during the next three hours. The results also ind icate that SMC production of PGI(2) is more sensitive to shear stress than PGE(2) production since a level of 0.5 dynes/cm(2) produces a max imal PGI(2) release whereas 1 dyne/cm(2) produces only 1/4 the respons e seen at 20 dynes/cm(2) for PGE(2). The physiological implications of fluid shear stress regulation of SMC are discussed. (C) 1996 Academic Press, Inc.