STRETCH INCREASES INOSITOL TRISPHOSPHATE AND INOSITOL TETRAKISPHOSPHATE IN CULTURED PULMONARY VASCULAR SMOOTH-MUSCLE CELLS

There are no reports of the effect of stretch on inositol phosphates in smooth muscle. Phosphoinositide and inositol phosphate metabolism was studied in cultured rat vascular smooth muscle cells subjected to stretching. The masses of inositol trisphosphate and tetrakisphosphate increased (+34 ± 7% and +58 ± 12%, respectively; p< 0.001) after 25 s of a single 20% stretch and had returned to control levels by 45 s; phosphatidylinositol, phosphatidylinositol phosphate and bisphosphate did not change. Repetitive stretch did not alter the masses of any of the compounds. A single stretch also increased 45Ca2+ efflux (+52 ± 5%, p< 0.01). These data suggest that stretch of cultured vascular smooth muscle can elicit a rapid, short-lived increase in inositol phosphates, which may subsequently affect Ca2+. © 1991 Academic Press, Inc.