thapsigargin and formic-acid

Although ethanol is known to inhibit platelet aggregation, the effects of another variant of alcohol, methanol, have not been reported. The purpose of this study was to determine whether methanol and its metabolite, formic acid, affect Ca. Thrombin-induced platelet aggregation was significantly augmented by methanol at pharmacological concentrations (0.5-2%) in a concentration-dependent manner. Methanol at 2% significantly attenuated thapsigargin-induced platelet aggregation, which was not significantly affected by lower concentrations (0.5 and 1%) of methanol. Methanol (0.5-2%) did not significantly affect platelet aggregation induced by 1-oleoyl-2-acetyl-sn-glycerol (OAG), or Ca. Methanol at pharmacological doses has diverse effects on platelet aggregation, depending on the aggregation stimuli, without affecting Ca

Topics: Blood Platelets; Calcium; Calcium Signaling; Diglycerides; Formates; Hemostatics; Humans; Methanol; Platelet Aggregation; Thapsigargin; Thrombin

The interaction between tubular epithelial cells and calcium oxalate crystals or oxalate ions is a very precarious event in the lithogenesis. Urine contains ions, glycoproteins and glycosaminoglycans that inhibit the crystallization process and may protect the kidney against lithogenesis. We examined the effect of oxalate ions and calcium oxalate crystals upon the synthesis of glycosaminoglycans in distal [Madin-Darby canine kidney (MDCK)] and proximal (LLC-PK1) tubular cell lines.. Glycosaminoglycan synthesis was analyzed by metabolic labeling with (35)S-sulfate and enzymatic digestion with specific mucopolysaccharidases. Cell death was assessed by fluorescent dyes and crystal endocytosis was analised by flow cytometry.. The main glycosaminoglycans synthesized by both cells were chondroitin sulfate and heparan sulfate most of them secreted to the culture medium or present at cellular surface. Exposition of MDCK cells to oxalate ions increased apoptosis rate and the incorporation of (35)S-sulfate in chondroitin sulfate and heparan sulfate, while calcium oxalate crystals were endocyted by LLC-PK1, induced necrotic cell death, and increased (35)S-sulfate incorporation in glycosaminoglycans. These effects seem to be specific and due to increased biosynthesis, since hydroxyapatite and other carboxylic acid did not induced cellular death or glycosaminoglycan synthesis and no changes in sulfation degree or molecular weight of glycosaminoglycans could be detected. Thapsigargin inhibited the glycosaminoglycan synthesis induced by calcium oxalate in LLC-PK1, suggesting that this effect was sensitive to the increase in cytosolic calcium.. Tubular cells may increase the synthesis of glycosaminoglycans to protect from the toxic insult of calcium oxalate crystals and oxalate ions, what could partially limit the lithogenesis.

Topics: Animals; Calcium; Calcium Oxalate; Cell Death; Cell Survival; Crystallization; Dogs; Durapatite; Endocytosis; Formates; Glycosaminoglycans; Ionophores; Ions; Kidney Tubules, Distal; Kidney Tubules, Proximal; LLC-PK1 Cells; Necrosis; Oxalates; Sulfates; Sulfur Radioisotopes; Swine; Thapsigargin; Urinary Calculi