The Biological Significance of Haemoglobin in Nematode Parasites II. The Properties of the Haemoglobins as Studied in Living Pabasites

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Abstract
In the parasites examined, the amounts of water-soluble hematin compounds, of which hemoglobin formed the large part, varied considerably, Nippostrongylus muris contained about 6 mg. (as hematin) per g. dry wt. of tissue, Nematodirus spp. and Haemonchus contortus about 0.8 mg. per g. dry wt. Evidence is presented which indicates that the hemoglobin of N. muris may be oxygenated in vivo, at least sometimes. The hemoglobin in the living parasites was easily oxygenated and deoxygenated; when the O2 tension in the medium surrounding the parasites in vitro at 37[degree]C fell below about 13 mm. of Hg (N. muris) or 9 mm. of Hg (H. contortus and Nematodirus spp.) the oxyhemoglobin became deoxygenated. The rate of O2 consumption by the 3 spp. was not significantly lessened by poisoning the hemoglobins with low concns. of CO at O2 tensions between 38 and 5 mm. of Hg. It is concluded that the hemoglobins, though present in sufficient amounts and apparently having suitable properties, are not actively concerned in the transport of O2 in the tissues of the parasites in vivo when the partial pressure of the O2 in the medium is above 5 mm. of Hg.

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