Sodium Fluoride – a Stimulus for a Calcium-Triggered Secretory Process

Self Cite

N-acetylcysteine (NAC) enhances the release of histamine induced by the fluoride-calcium system but not by compound 48/80. After preincubation of the cells for 2 h at room temperature (RT) as well as at 37°C, NAC was found to enhance histamine release also when induced by compound 48/80. Both fluoride treatment and prolonged incubation at 37°C (but not at RT) for 2 h decreased the ATP content of the cells. NAC was found to counteract the fall in ATP caused by prolonged incubation of the cells at 37°C but not when induced by exposure to sodium fluoride. The results do not favor the concept that free radicals generated by fluoride treatment are responsible for the subsequent sensitivity of the cells to the secretory action of calcium. On the other hand, it cannot be excluded that free radicals generated during prolonged incubation of the cells at 37°C might be involved in the decrease of the sensitivity of the cells to the secretory action of the fluoride-calcium system and of compound 48/80. This is supported by the finding that the presence of NAC not only activated the secretory response but also counteracted the decrease of the cellular ATP content noted following preincubation of the cells for 2 h at 37°C.

Section: Discussionsupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Effects of N-Acetylcysteine on Histamine Release by Sodium Fluoride and Compound 48/80 from Isolated Rat Mast Cells

Hong

Francker²,

Diamant³

1991

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“…3) suggests an enhanced diffusion of fluoride at low pH and therefore faster activation of the cells to the secretory action of calcium. The decreased secretory response observed after prolonged incubation at low pH indicates that an additional mech anism comes into play which is inhibitory to secretion, as for example an inhibition by fluoride on cellular ATP generation [Patkar et al, 1977b], The inability of these cells to respond to the secretory action of A23187 may support this opinion. At pH 7.0 a grad ual slow activation was noted during the first 15 min of incubation, and this effect was markedly depressed when the cells were incubated at pH 8.9 during activation.…”

Section: Discussionmentioning

confidence: 97%

“…This latter action of fluoride cannot be due to a metabolic effect since calcium trig gered secretion from fluoride-activated cells, and, furthermore, compound 48/80 re leased histamine from fluoride-activated cells, provided strontium or calcium was added to the cells [Patkar et al, 1977b], Instead, in analogy with the inhibitory action of EDTA and A23187 on the secre tory response induced by compound 48/80 in the absence of calcium, it is suggested that fluoride binds cellular calcium which can normally be utilized by compound 48/80 to trigger suboptimal release. This finding indicates that membrane-bound cal cium is more easily available to fluoride than those sites responsible for cell activa tion.…”

Section: Discussionmentioning

confidence: 99%

Histamine Release by Calcium from Sodium Fluoride-Activated Rat Mast Cells. Further Evidence for a Secretory Process

Patkar¹,

Kazimierczak²,

Diamant³

1978

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Histamine release induced by calcium (step 2) from fluoride-activated (step 1) rat mast cells was found to be dependent on temperature and pH. Whereas the influence of temperature was different on the two steps, the pH effects were similar. The activation of the cells by fluoride occurred faster at low pH. Agents considered to influence cyclic nucleotide content of the cells neither influenced fluoride activation nor the secretory action of calcium, except for theophylline which inhibited the second step and shared this effect with lidocaine and several other agents known to act as inhibitors of histamine secretion. The time course for the action of fluoride to inhibit subsequent histamine release by compound 48/80 in the absence of extracellular calcium was somewhat faster than its action to activate the cells to the secretory action of calcium. In the absence of calcium, no cyclic AMP could be detected in the cells. In the presence of 1 mM calcium, 2.5 pmol/10⁶ cells cyclic AMP was found which decreased by the presence of fluoride. No uptake of ⁴⁵Ca was observed in fluoride-activated mast cells in the absence of release. Furthermore, fluoride did not activate isolated mast cell granules to release histamine when challenged with calcium. The results suggest that calcium-induced histamme secretion from fluoride-activated cells conforms to a secretory system which, in many respects, is governed by similar regulatory factors as for antigen and other secretagogues.

“…The mechanism by which sodium fluoride-calcium releases histamine is not well understood, but it seems rea sonable to assume that the release of histamine is medi ated by the influx of calcium through the plasma mem brane [17,18], These results seems to indicate that the al teration on the cell during the purification procedure takes place in some piasma-membranc-relatcd pathway. Overall, we can conclude that in the study of signal trans duction it is very important to bear in mind the purifica tion medium and the type of stimulus employed.…”

Section: Discussionmentioning

confidence: 99%

Rat Pleural and Peritoneal Mast Cells Stimulated at Different Cellular Levels: Difference in and Influence of Purification Media

Cabado¹,

Vieytes²,

Botana³

1993

We checked the effect that purification through different media can produce on rat mast cell response, considering different populations of pleural and peritoneal mast cells. We compared the media Ficoll®, Percoll®, bovine serum albumin and sucrose with the seldom used Nycodenz®. Histamine release was elicited with compound 48/80, polymyxin B, ionophore A23187 and calcium on cells preincubated with FNa. High osmolarity media induced the most important changes on the cell response as compared to low osmolarity media. Our results show that Ficoll and sucrose induced the most notable changes in the response. Also, the more sensitive stimulus to the purification procedure is sodium fluoride-calcium. The response to ionophore A23187 did not show any important alteration.