title: Adaptation of cytochrome-b5 reductase activity and methaemoglobinaemia in areas with a high nitrate concentration in drinking-water.
abstract: An epidemiological investigation was undertaken in India to assess the prevalence of methaemoglobinaemia in areas with high nitrate concentration in drinking-water and the possible association with an adaptation of cytochrome-b5 reductase. Five areas were selected, with average nitrate ion concentrations in drinking-water of 26, 45, 95, 222 and 459 mg/l. These areas were visited and house schedules were prepared in accordance with a statistically designed protocol. A sample of 10% of the total population was selected in each of the areas, matched for age and weight, giving a total of 178 persons in five age groups. For each subject, a detailed history was documented, a medical examination was conducted and blood samples were taken to determine methaemoglobin level and cytochrome-b5 reductase activity. Collected data were subjected to statistical analysis to test for a possible relationship between nitrate concentration, cytochrome-b5 reductase activity and methaemoglobinaemia. High nitrate concentrations caused methaemoglobinaemia in infants and adults. The reserve of cytochrome-b5 reductase activity (i.e. the enzyme activity not currently being used, but which is available when needed; for example, under conditions of increased nitrate ingestion) and its adaptation with increasing water nitrate concentration to reduce methaemoglobin were more pronounced in children and adolescents.
authors.affiliation: Satellite Hospital, Banipark, Jaipur, India.
authors.forename: S K
authors.initials: SK
authors.lastname: Gupta
authors.forename: R C
authors.initials: RC
authors.lastname: Gupta
authors.forename: A K
authors.initials: AK
authors.lastname: Seth
authors.forename: A B
authors.initials: AB
authors.lastname: Gupta
authors.forename: J K
authors.initials: JK
authors.lastname: Bassin
authors.forename: A
authors.initials: A
authors.lastname: Gupta
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D002648:Child; D002675:Child, Preschool; D003579:Cytochrome Reductases / Q000032:analysis*; D006801:Humans; D007194:India / Q000453:epidemiology; D007223:Infant; D008706:Methemoglobin / Q000032:analysis; D008708:Methemoglobinemia / Q000175:diagnosis / Q000453:epidemiology*; D008875:Middle Aged; D009566:Nitrates / Q000032:analysis*; D013056:Spectrophotometry, Ultraviolet; D014867:Water / Q000737:chemistry*; D014881:Water Supply
chemical_list: D009566:Nitrates; D014867:Water; D008706:Methemoglobin; D003579:Cytochrome Reductases