Taichi Nakajima

Nitrosyl-Hemoglobin Formation in the Blood of Animals Exposed to Nitric Oxide

Animals were exposed to nitric oxide (NO) in order to study its biological effect. First a method was developed to exclude nitrogen dioxide formed during exposure of NO. Nitrosyl-hemoglobin (NOHb) in the blood of mice, rats, and rabbits exposed to NO was determined by electron spin resonance spectrometry at -100C. The content of NOHb in the blood of the mouse reached the maximum (0.13% of the total hemoglobin) 20 minutes after the exposure was begun and thereafter a state of equilibrium was maintained. The NOHv level decreased to one half in several minutes after the mouse was removed to a filtered air environment. Dose-response relationship was observed between gas concentrations and the maximum NOHb level.

Reaction of hemoglobin with nitric oxide and nitrogen dioxide in mice

The reaction of hemoglobin with NO and NO2 was compared in mice exposed to these cases. Nitrosyl hemoglobin (NOHb) and methemoglobin (MetHb) were determined simultaneously by electron spin resonance spectrometry at -140 degrees C. In mice exposed to 40 ppm NO, NOHb became constant (0.7%) in 30 min and declined rapidly with a half-life of several minutes when the mice were removed to room air. An increase of MetHb (5%) was also caused by exposure to NO and the time course was almost the same as that of NOHb. Exposure to 40 ppm NO2 produced only NOHb (0.2%); MetHb did not increase. The time course of NOHb was identical to that observed with NO exposure. Dose-effect relationships were determined with both gases at concentrations ranging from 20 to 80 ppm. A linear relationship could be observed between the concentrations of the gases and NOHb, but NO produced more NOHb than did NO2. There was an exponential increase of MetHb, particularly at high concentrations of NO.

Effects of ozone and photochemical oxidants on interferon production by rabbit alveolar macrophages

The results obtained in this study demonstrated that the capacity of interferon production by alveolar macrophage was depressed immediately after exposure to O/sub 3/ greater than 1 ppM or Ox exceeding average of 0.3 ppM (max. 0.7 ppM) for 3 hours. In these experiments, it was shown that depression in interferon production corresponded in degree to elevation of gas concentration. This finding suggested that alveolar macrophages, existing in a state of single cell in the lung, were probably exposed directly to the inhaled gas in this experimental system. The results that depression of interferon production in Dutch rabbit under the same O/sub 3/ concentration was greater in degree than that in rabbit suggest that sensitivity of alveolar macrophage to O/sub 3/ or presumably to other irritating gases is different among species.

Methemoglobin formation by nitrobenzene in vitro

SummaryA small amount of methemoglobin was formed in vitro by incubating human or rabbit hemoglobin with nitrobenzene, a substance which has not been considered to form methemoglobin. After incubation with nitrobenzene, the oxidase activity of hemoglobin increased, and the alkali resistance of hemoglobin decreased. However, neither hemichromogen nor choleglobin was detected in the hemolysate after incubation. These facts show that nitrobenzene acts directly on and transforms the hemoglobin causing the heme iron to be changed to the ferric state. The molecular structure of methemoglobin was also discussed.

The Effect of Ozone and Photochemical Oxidants on the Interferon Production by Tonsillar Lymphocytes

In order to elucidate the biological effects of photochemical smog on the tonsil, lymphocytes from human tonsil were exposed to ozone and rabbits were exposed to ozone or photochemical oxidants. The tonsillar lymphocytes were studied for interferon production by Newcastle disease virus and blastoid transformation by PHA. Both interferon production by and blastoid transformation of the human tonsillar lymphocytes decreased markedly on exposure to ozone. Tonsillar lymphocytes from rabbits exposed to photochemical oxidants showed a significant decrease in interferon production. The decrease in interferon production in tonsillar lymphocytes from the rabbit exposed to photochemical oxidants was greater in magnitude than the decrease in interferon production in tonsillar lymphocytes exposed to ozone or non-irradiated automobile exhaust gas. The difference in blastoid transformation between the exposed groups and controls was not significnat. The results suggest that exposure to photochemical oxidants causes some functional changes in tonsillar lymphocytes.

Nitrosylhemoglobin and carboxyhemoglobin in the blood of mice simultaneously exposed to nitric oxide and carbon monoxide.

A comparative study of the toxicological effects of nitric oxide (NO) and carbon monoxide (CO). The concentration of Nitrosylhemoglobin (NoHb) and carboxyhemoglobin in the blood of mice exposed to NO and CO was determined. Results show little difference in NOHb and COHb levels between simultaneous exposure and separate exposure to NO and CO. This indicates little of no interaction of hemoglobin binding at concentrations used in this experiment. (JWP)