Aspirin, indomethacin, and tartrazine increase carotid-sinus-nerve activity and arterial blood pressure in guinea pigs

High-Dose Aspirin Reverses Tartrazine-Induced Cell Growth Dysregulation Independent of p53 Signaling and Antioxidant Mechanisms in Rat Brain

Tartrazine, an azo dye used in food, cosmetics, and pharmaceuticals with the effects on cell cycle, is not well understood. Therefore, we investigated the toxicity of tartrazine in rat brain with high-dose aspirin. Male Wistar rats (n = 24) were divided into (C) control, (T) tartrazine (700 mg/kg body weight [BW] at weeks 1 and 2), (A) aspirin (150 mg/kg [BW] at weeks 1, 2, and 3), and (TA) aspirin + tartrazine (150 mg/kg [BW] aspirin at weeks 1, 2, and 3 and 700 mg/kg [BW] tartrazine at weeks 1 and 2) groups. The expression of p53, B cell lymphoma-2 extra-large (Bcl-xL), cyclin-dependent kinase 2 (CDK2), p27, and Ki67 was evaluated by quantitative reverse-transcription PCR. A histopathological analysis of brain tissue and oxidative stress level was assessed based on reduced glutathione (GSH), ascorbic acid (AA), and malondialdehyde levels. We found that Bcl-xL, Ki67, CDK2, and p27 were upregulated and p53 was downregulated in the tartrazine-treated group as compared to the control group. Aspirin administration reversed these changes except P53 expression. Tartrazine had no effect on lipid peroxidation but altered AA and GSH levels with no reversal by aspirin treatment. Histopathological analysis revealed that aspirin prevented tartrazine-induced damage including increased perivascular space and hemorrhage. These results indicate that aspirin protects the brain from tartrazine-induced toxicity independent of p53 signaling and antioxidant mechanisms.

Adverse reactions to synthetic food colours: interactions between tartrazine and muscarinic acetylcholine receptors in isolated guinea-pig ileum

The ability of selected food colours to interact with isolated guinea-pig ileum was investigated using a gut bath system. Studies revealed that guinea-pig ileum was specifically sensitive to tartrazine. Intestinal contraction occurred dose-dependently down to a minimum effective dose of 10 microM. All other colours examined proved negative. Studies investigating the biological activity of structural analogues of tartrazine revealed the ability to initiate intestinal contraction was associated with the presence of the carboxylic acid residue at the R1 position of the pyrazole ring. Blocking studies showed that tartrazine contraction was inhibited by atropine alone but not by any other blocking agent tested, implying that tartrazine acts either directly or indirectly upon the muscarinic acetylcholine receptor associated with parasympathetic innervation.

Prostaglandins contribute to activation of baroreceptors in rabbits. Possible paracrine influence of endothelium

The purpose of this study was to test the hypothesis that prostaglandins released from vascular endothelial cells contribute to activation of baroreceptors during increases in arterial pressure. Baroreceptor activity was recorded from the vascularly isolated carotid sinus in rabbits anesthetized with chloralose. Baroreceptor activity was measured during ramp or step increases in nonpulsatile carotid sinus pressure over a range of 0-175 mm Hg. Exposure of the isolated carotid sinus to inhibitors of prostaglandin formation (indomethacin [n = 10] or aspirin [n = 6]) decreased baroreceptor activity significantly (p less than 0.05). The slope of the pressure-activity relation averaged 0.80 +/- 0.07 %/mm Hg (mean +/- SEM) during control measurements and 0.72 +/- 0.06 and 0.63 +/- 0.05 %/mm Hg during exposure to 10 and 20 microM indomethacin, respectively. Exposure of the carotid sinus to exogenous prostacyclin (PGI2 [n = 11]) increased baroreceptor activity significantly. The slope of the pressure-activity relation averaged 0.89 +/- 0.10, 1.09 +/- 0.09, and 1.26 +/- 0.16 %/mm Hg during control and during exposure to 10 and 20 microM PGI2, respectively. Activity returned to control after removal of PGI2 (0.89 +/- 0.12 %/mm Hg). Removal of endothelium with either a balloon catheter (n = 4) or a jet of a 95% O2-5% CO2 gas mixture (n = 6) decreased the slope of the pressure-activity relation from 0.92 +/- 0.09 to 0.56 +/- 0.08 %/mm Hg (p less than 0.05). Exposure of the denuded sinus to exogenous PGI2 (20 microM [n = 4]) restored activity (slope = 1.09 +/- 0.24 %/mm Hg). Neither indomethacin (n = 5) nor PGI2 (n = 5) nor denudation (n = 5) significantly altered the pressure-diameter relation of the carotid sinus (sonomicrometers), suggesting that the effects on baroreceptor discharge are not caused by altered stretch of the carotid sinus at a given pressure. The results suggest that prostaglandins (e.g., PGI2) released from endothelium contribute in a paracrine manner to activation of baroreceptors during increases in arterial pressure.