INHIBITION OF GLYCOLYSIS BY 2-DG INCREASES [CA2-MUSCLE CELLS(](I) IN PULMONARY ARTERIAL SMOOTH)

Inhibition of glycolysis depolarizes single pulmonary arterial smooth muscle cells (PASMC) and potentiates hypoxic pulmonary vasoconstrictio n (HPV) in isolated perfused rat lungs. Whether glycolytic inhibition causes an increase in the intracellular Ca2+ concentration ([Ca2+](i)) in PASMC was determined in this study. [Ca2+](i) was measured in prim ary cultured rat PASMC using the Ca2+-sensitive fluorescent indicator, fura 2, and quantitative fluorescence microscopy. Extracellular appli cation of the glycolytic inhibitor, 2-deoxy-D-glucose (2-DG), signific antly and reversibly increased [Ca2+](i) in PASMC. Removal of extracel lular Ca2+ and application of the Ca2+ channel blocker, verapamil (10 mu M), attenuated, but did not eliminate, the 2-DG-induced rise in [Ca 2+](i). In the absence of extracellular Ca2+, however, depletion of in ositol triphosphate-sensitive intracellular Ca2+ stores by 10 mu M cyc lopiazonic acid (CPA) completely abolished the 2-DG-induced increase i n [Ca2+](i). The data suggest that 2-DG-induced increases in [Ca2+](i) result from both Ca2+ influx through the verapamil-sensitive voltage- gated Ca2+ channels and Ca2+ release from the CPA-sensitive intracellu lar Ca2+ stores.