Although humans and many other organisms have the enzyme needed to produce nitric oxide, C. elegans does not. Instead, Dr. Nudler and his team report in the February 14th online issue of Cell that the worm can "hijack" the compound from the soil-dwelling Bacillus subtilis bacterium that is not only a favored food but also a common colonist within its gut. This resourcefulness, Dr. Nudler says, partially explains why worms fed B. subtilis live roughly 50 percent longer than counterparts fed Escherichia coli , which does not produce the compound.
While it would probably be improper to say that N 2 O is completely
non-toxic, we can say that there has been no evidence of any significant
effects on any tissues as long as there is short term use of N 2 O.
Caution is suggested when mitotic activity may be present.
It should be noted that a single administration of N 2 O does inhibit bone marrow hematopoiesis. However, normal marrow contains a sufficient store of blood cells to maintain a normal number in the circulation for several days. Production returns to normal in three or four days, and no detectable drop in circulating cells is seen from a single administration of N 2 O. However, repeated administrations within a short period of time will continue to inhibit cell production, which may exceed the capacity of stored cells, and lead to leukopenia. Therefore, repeated administrations of N 2 O more frequently than once a week would seem to be inadvisable.
Recent studies indicate that prolonged N 2 O exposure reduce the pluripotent hemopoietic stem cells and granulocyte-macrophage progenitor cells in bone marrow up to 40%. In addition, spontaneous abortion, birth defects, cancer, and possibly liver disease has been contributed to prolonged N 2 O exposure. Long term toxicity will be discussed in more detail later in the course.
Nitrous oxide remains non-allergenic. There has never been a reported allergic reaction to N 2 O 3 .