Dimethylaminoethanol affects the viability of human cultured fibroblasts.

BACKGROUND: In clinical practice, dimethylaminoethanol (DMAE) has been used in the fight against wrinkles and flaccidity in the cervicofacial region. The firming action of DMAE is explained by the fact that its molecule, considered to be a precursor of acetylcholine, alters muscle contraction. However, no experimental studies have confirmed this theory. Because the actual mechanism of DMAE action was not defined and there were no references in the literature regarding its direct action on fibroblasts, this study was performed to evaluate the direct action of DMAE on cultured human fibroblasts. METHODS: Human fibroblasts obtained from discarded fragments of total skin from patients undergoing plastic or reconstructive surgical procedures performed within the Plastic Surgery Division at the Federal University of São Paulo were used for this study. The explant technique was used. The culture medium was supplemented with different concentrations of DMAE on the fourth cell passage, and the cell proliferation rate, cytosolic calcium levels, and cell cycle were evaluated. Statistical analysis was performed using analysis of variance (ANOVA) followed by a Newman-Keuls test for multiple comparisons. RESULTS: A decrease in fibroblast proliferation was associated with an increase in DMAE concentration. A longer treatment time with trypsin was required for the groups treated with DMAE in a dose-dependent manner. In the presence of DMAE, cytosolic calcium increased in a dose-dependent manner. Apoptosis also increased in groups treated with DMAE. CONCLUSION: Dimethylaminoethanol reduced the proliferation of fibroblasts, increased cytosolic calcium, and changed the cell cycle, causing an increase in apoptosis in cultured human fibroblasts.

Problems caused by high concentration of ATP on activation of the P2X7 receptor in bone marrow cells loaded with the Ca2+ fluorophore fura-2.

Fura-2 is one of the most used fluorophore for measuring intracellular calcium concentration ([Ca2+]i). In mouse bone marrow cell suspensions ATP produces a biphasic effect: till 1 mM, ATP produces increases in [Ca2+]i; from 1 mM on an increase is observed, that is followed by the decrease in the 340/380 nm ratio (R340/380). At high ATP (4 mM) concentration fura-2 leaked from loaded bone marrow cell suspensions. We observed that ATP decreases fluorescence in the absorption and excitation spectra of fura-2, consequently the emitted one is decreased including the isobestic point (360 nm). ATP analogs: BzATP, ATPyS and UTP, but not alphabetaATP, ADP or AMP, promote decrease of fluorescence in the isobestic point of fura-2. The physical/chemical process that reduces the absorption and excitation of fura-2 by ATP is unknown. The P2X7 inhibitors, Mg2+ (5 mM), OxATP (300 microM) and Brilliant Blue (100 nM), blocked the efflux of fura-2 and ATP-induced R340/380 decrease. The J774 cell line and mononuclear cells with a higher expression of P2X7 receptors show the same decrease in R340/380 as that induced by ATP. In the HL-60 cell line, myeloid cells and erythroblasts extracted from bone marrow, such effect does not occur. It is concluded that the use of the fluorescent Ca2+ indicator fura-2 does not allow the correct measurement of [Ca2+]i in these cells in the presence of a higher concentration of ATP which activated the P2X7 receptor.