Proceedings of the Physiological Society, 20‐21 July 1984, Cambridge Meeting: Communications

Abstract

It has long been known that the haemoglobin of neonates, juveniles and pregnant women is more susceptible to methaemoglobinization by sodium nitrite than that of adults. In 1981 we (Metcalf, Metcalf & Tarburton) reported to the Society that this reaction takes place in two phases, a lag and a log phase, and that both are longer in haemoglobin obtained from adults.The recently acquired reputation of alkyl nitrites (amyl and butyl) as aphrodisiacs has led to an increase in their inhalation by children and adults resulting in a number of deaths. We therefore decided to investigate the reaction of this class of compounds with haemoglobin in vitro.Two ml samples of cord blood and adult blood were collected by venepuncture in EDTA vacutainers. After washing, the red cells were haemolysed in distilled water, and the haemoglobin concentration adjusted to a consistent value in the cuvette of a recording spectrophotometer. This enabled the methaemoglobinization reaction, when a measured amount of nitrite was mixed with the haemoglobin, to be followed.In contrast to the reaction of sodium nitrite with haemoglobin, the reaction commenced immediately, i.e. there was no lag phase. However, the difference in sensitivity between the haemoglobin of cord blood and that of adult blood was even more pronounced than in the reaction with sodium nitrite. The reaction rate was proportional to the concentration of both amyl nitrite and haemoglobin; it was reduced by the addition of superoxide dismutase, but was unaffected by the addition of catalase to the reaction mixture.Whilst further work is clearly needed, it would seem advisable to avoid exposing pregnant women, neonates and probably juveniles to organic nitrites.