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Macrophages Respond to Microgravity in 8 Seconds: We asked the questions, do macrophages respond to microgravity? If so, how long does it take to respond? We addressed these questions by monitoring macrophage spreading during parabolic flight on the NASA KC-135 aircraft. It was monitored using weak electric fields in which a circuit was constructed which contained a variable impedance induced by cell spreading. The cells used were from the macrophage cell line B6MP102. B6MP102 cells were derived from bone marrow cells grown in the presence of macrophage colony stimulating factor. These cells function and appear to be very similar to differentiated macrophages isolated from animals and are dependent on macrophage colony stimulating factor for cell growth. B6MP102 cells were allowed to spread on a silver electrode. A current of approximately 1 uA was passed through the circuit causing a variable voltage proportional to the impedance created by the amount of spreading by the B6MP102 cells. Therefore, as the cell spreading changed the amount of voltage detected changed.
Panel A: Cell adherence (bottom line in panel A) during turbulent (reflected by the accelerometer movement; top line) or smooth flight.
Panel B: Cell adherence during microgravity or hypergravity during parabolic flight. B6MP102 cells begin to spread about 8 seconds into a microgravity episode. They return to their original orientation when the airplane returns to 1 x g or goes into hypergravity episodes.
Conclusion: Macrophages can respond to microgravity within 8 seconds. Spreading is not affected by turbulent flight. Therefore, the macrophage response only occurs during sustained microgravity episodes.