Direct measurement of nitric oxide (NO) in the gastrointestinal tract of cod (Gadus morhua)

Abstract

Objective: In mammals, the biological messenger nitric oxide (NO) is generated throughout the gastrointestinal (GI) tract from the reduction of dietary nitrate and nitrite. The aim of the present study was to investigate the amount of GI NO in Atlantic cod (Gadus morhua) in relation to intake of food. Methods: A total of 28 cod were divided into 3 groups, fed at different times before the experiment (1 week, 1 day, and 3 h, respectively). Results: In the stomach, the measured NO concentrations were consistently higher in the group fed 3 h before the measurement, implying that the NO3-NO2-NO pathway is present in the stomach of cod. We also measured the NO concentration in the large intestine. Again, the values were higher in cod fed 3 h before the experiment. Conclusion: We conclude that NO is formed in the GI tract of cod, likely via the reduction of dietary nitrate and nitrite. The physiological importance of this NO production remains to be determined.