Pulmonary neuroendocrine cells: decreased serotonin fluorescence and stable argyrophil-cell numbers in acute hypoxia.

We recorded serotonin-emission intensity using formalin induced fluorescence and counted the number of neuroendocrine cells (NEC's) and neuroepithelial bodies (NEB's) containing argyrophil granules. Comparison of serotonin-emission intensity of NEB's of acutely hypoxic neonates (520 mmHg for 2-2 1/2 h) and normoxic controls showed significantly lower fluorescence in hypoxic animals. Neuroendocrine cell numbers as shown wit Grimelius silver-nitrate stain did not change. This suggests either that the Grimelius stain reacts with compounds other than serotonin, or that the decrease in serotonin in acutely hypoxic rabbits is not sufficient to alter argyrophil stainability.