In order to study the potential benefit of ascorbic acid in asthma we investigated its role in exercise-induced bronchospasm (EIB). Twelve asthmatic subjects were recruited on the basis of findings compatible with EIB. On two subsequent days the subjects ingested 500 mg. of ascorbic acid or a placebo. The study was performed in a double-blind randomized fashion. Partial and maximal expiratory f...

A recent finding from this laboratory indicated that the incubation in vitro of purified xanthine oxidase with trace amounts of l-ascorbic acid resulted in a marked inhibition of the enzymatic activity (1, 2). Since the physiological mode’of action of Z-ascorbic acid is still obscure, it seemed desirable to determine whether ascorbic acid would, in the intact animal, exert a similar effect on x...

Human tumors may contain high concentrations of ascorbic acid, but little is known about how they acquire the vitamin. Certain specialized cells can transport ascorbic acid directly through a sodium ascorbate cotransporter, but in most cells, vitamin C enters through the facilitative glucose transporters (GLUTs) in the form of dehydroascorbic acid, which is then reduced intracellularly and reta...

Ascorbic acid and glutathione (GSH) are important determinants of the intracellular redox state, and both are known to accelerate the decomposition of S-nitrosoglutathione (GSNO), an endogenous adduct of nitric oxide (NO). The implications of these observations for GSNO bioactivity are not yet clear. We investigated the effect of ascorbic acid and GSH on GSNO bioactivity by using a bioassay wit...

Repeated administration of nicotine causes incentive and behavioral sensitization in animals. Ascorbic acid administration inhibits some effects of nicotine. In the present study, the effect of ascorbic acid administration on nicotine-induced behavioral sensitization in Male Swiss-Webster mice (20-25 g) was investigated. Animals were injected with nicotine (0.25 mg/kg, i.p.) once daily for seve...

the effects of thiamine, ascorbic acid ami their combination an workers who are continuously exposal to lead has been investigated. in this study 60 persons in a battery industry was selected and divided into four equal groups. group i received placebo, group ii thiamine (300 mg), group iii ascorbic acid (250 mg) anil group iv thiamine (300 mg) plus ascorbic acid (250 mg) three times a day (ora...

A method was developed for assessing ascorbic acid concentration in commercial fruit juice by cyclic voltammetry. The anodic oxidation peak for ascorbic acid occurs at about 490 mV on a Pt disc working electrode (versus SCE). The influence of the potential sweep speed on the peak height was studied. The obtained calibration graph shows a linear dependence between peak height and ascorbic acid c...

Ascorbic acid enhancement of norepinephrine formation from tyrosine in cultured bovine chromaffin cells was characterized in detail as a model system for determining ascorbate requirements. In resting cells, ascorbic acid increased dopamine beta-monooxygenase activity without changing tyrosine 3-monooxygenase activity. [14C]Norepinephrine specific activity was increased by ascorbic acid, while ...

Both ascorbic acid and copper were strong prooxidants in the oxidation of linoleate in a buffered (pH 7.0) aqueous dispersion at 37 degrees C. Minimum concentrations at which catalytic activity was detected were 1.3 x 10(-7) m for copper and 1.8 x 10(-6) m for ascorbic acid. For concentrations up to 10(-3) m, the increase in rate of oxidation with increase in concentration of catalyst was great...

Ionotropic GABA receptors (GABA(A) and GABA(C)) belong to the Cys-loop receptor family of ligand-gated ion channels. GABA(C) receptors are highly expressed in the retina, mainly localized at the axon terminals of bipolar cells. Ascorbic acid, an endogenous redox agent, modulates the function of diverse proteins, and basal levels of ascorbic acid in the retina are very high. However, the effect ...