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The fine structure of the secondary lamellae of gills was examined in two cold-water marine teleosts, the winter flounder, Pseudopleuronectes americanus, and the antarctic cod, Trematomus borchgrevinik. In both species the overall lamellar fine structure is similar to that of other marine teleosts. The major variations in cellular organization involve the distribution of both the "chloride cells" and the mucous cells on the secondary lamellae of P. americanus. At winter water temperatures of +2.5 degrees C, significantly more chloride and mucous cells are present than in summer with water temperatures of +15.2 degrees C. Both cell types are routinely present throughout the length of a secondary lamella as far as the lamellar tip. The chloride cells on the secondary lamellae are always situated in the inner layer of epithelium deep to the outer pavement cells. T. borchgrevinki shows no apparent difference in the distribution of mucous cells either at its normal water temperature of -1.9 degrees C or at a temperature of +4 degrees C, the upper limit of its thermal tolerance to which some specimens were adapted in the aquarium. Chloride cells were never observed on the secondary lamellae of T. borchgrevinki. This suggests that low environmental water temperatures may be related to the distribution of mucous cells and chloride cells on the secondary lamella of the teleost gill.

A patient with a lymphoproliferative disorder, angioedema, and an acquired deficiency of the inhibitor of the activated first component of complement was studied. The patient's complement profile revealed depletion of the first component of complement, which has not been seen in angioedema of the hereditary type. There was no evidence for C1- depleting activity in the patient's plasma. The majority of the patient's peripheral blood mononuclear cells resembled B cells in their memebrane receptor properties and in that they carried easily detectable immunoglobulin, predominantly IgM. However, these cells were unusual in that they phagocytosed both latex particles and C3-coated erythrocytes. Morphological study of the cells infiltrating the patient's lung revealed immature, atypical, and plasmacytoid lymphocytes and immunoblasts. Both the patient's peripheral blood mononuclear cells and a suspension of cells from the pulmonary infiltrate were capable of depleting the first component of complement and its inhibitor from homologous plasma. Normal ABO-compatible cells did not possess this property. The data suggested that the patient's abnormal lymphoid cells may have interacted with the complement system to produce a biochemical defect and a clinical syndrome closely resembling angioedema of the hereditary type.

In six anesthetized and mechanically ventilated adult sheep, the bronchial artery was perfused with blood from an oxygenator-pump circuit. When the lungs were ventilated with 100% O2 and the bronchial O2 tension (PbrO2) was approximately 600 Torr, the mean of the pulmonary vascular resistances (PVR) measured at the beginning (3.32 +/- 0.29 units) and end (3.17 +/- 0.13 units) of the experiment was 3.24 +/- 0.20 units. When the PbrO2 was changed to 58 +/- 1 Torr, the PVR (2.99 +/- 0.14 units) did not change significantly. However, when the lungs were ventilated with air as PbrO2 was decreased to 91 +/- 4, 77 +/- 3, 56 +/- 2, and 42 +/- 1 Torr, the PVR increased to 3.67 +/- 0.18, 4.03 +/- 0.16, 4.79 +/- 0.19, and 4.71 +/- 0.35 units, respectively. However, when the PbrO2 was decreased further to 26 +/- 1 and 13 +/- 1 Torr, the PVR decreased to 3.77 +/- 0.28 and 3.91 +/- 0.30 units, respectively. In contrast, the bronchial vascular resistance decreased monotonically as PbrO2 decreased. The bronchial circulation supplies vasa vasorum to the walls of all but the smallest pulmonary arteries, and it is therefore suggested that the PO2 of the bronchial circulation is responsible for the bimodal response of the pulmonary vasculature, with stimulation of hypoxic pulmonary vasoconstriction at moderate hypoxemia and of hypoxic pulmonary vasodilation at profound hypoxemia. The physiological and pathophysiological significance of the influence of systemic PO2 on pulmonary vascular tone is discussed.

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