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Selective inhibition of agonist‐induced but not shear stress‐dependent release of endothelial autacoids by thapsigargin
Author(s) -
Macarthur Heather,
Hecker Markus,
Busse Rudi,
Vane John R.
Publication year - 1993
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1993.tb13446.x
Subject(s) - thapsigargin , endocrinology , medicine , ionomycin , bradykinin , endothelium , chemistry , biology , biophysics , stimulation , calcium , receptor
1 The effects of the Ca 2+ ‐ATPase inhibitor, thapsigargin, on the shear stress‐dependent and on the agonist‐stimulated release of endothelium‐derived relaxing factor, i.e. nitric oxide (NO), and prostacyclin (PGI 2 ) were studied in bovine and human cultured endothelial cells as well as in endothelium‐intact arterial segments of the rabbit. 2 Preincubation with thapsigargin (1 μ m for 10 min) had no effect on the shear stress‐dependent release of NO from bovine aortic endothelial cells grown on beads, but abolished the release of NO induced by ADP, bradykinin, ionomycin or poly‐ l ‐lysine. Similarly, thapsigargin completely abrogated the agonist‐stimulated PGI 2 release from these cells, but had no effect on the shear stress‐dependent release of PGI 2 . 3 The acetylcholine‐induced release of NO from the luminally perfused thoracic aorta and femoral artery of the rabbit was suppressed by pretreatment with thapsigargin (1 μ m ). In contrast, thapsigargin did not affect the shear stress‐dependent release of NO from the femoral artery. 4 Administration of thapsigargin to these vascular preparations or to cultured endothelial cells alone produced a substantial release of both NO and PGI 2 . This release declined towards previous values after washout of thapsigargin. 5 In human and bovine cultured endothelial cells, thapsigargin (1–1000 n m ) caused a dose‐dependent sustained rise in [Ca 2+ ] i , an effect that was abolished in the absence of extracellular Ca 2+ . Stimulation of these cells with bradykinin, histamine, ADP or ionomycin after previous exposure to thapsigargin (30–1000 n m ) no longer caused an increase in [Ca 2+ ] i . 6 These findings demonstrate that by emptying intracellular Ca 2+ stores, thapsigargin selectively blocks the agonist‐stimulated release of both NO and PGI 2 , suggesting a principal difference in the control by [Ca 2+ ] i of the release of these endothelial autacoids caused by shear stress or receptor‐dependent and independent agonists.