1995 Fiscal Year Final Research Report Summary

Intracellular pressure measurements in motile cells.

Research Project

Project/Area Number	06670600
Research Category	Grant-in-Aid for General Scientific Research (C)
Allocation Type	Single-year Grants
Research Field	Respiratory organ internal medicine
Research Institution	Tohoku University
Principal Investigator	YANAI Masaru Tohoku Univ., School of Medicine. Assist. professor, 医学部附属病院, 講師 (00210287)
Project Period (FY)	1994 – 1995
Keywords	Ameboid movement / Pseudopod formation / Servo-null technique / servo-null technique
Research Abstract	The cortical filament layr of free-living amoebae contains concentrated actomyosin, suggesting that it can contract and produce an internal hydrostatic pressure. We report here on direct and dynamic intracellular pressure (P_<ic>) measurements in Amoeba proteus made using the servo-null technique. In resting apolar A.proteus, P_<ic> increased while the cells remained immobile and at apparently constant volume. P_<ic> then decreased approximately coincident with pseudopod formation. There was a positive correlation between P_<ic> at the onset of movement and the rate of pseudopod formation. These results are the first direct evidence that hydrostatic pressure may be a motive force for cell motion. We postulate that contractile elements in the amoeba's cortical layr contract and increase P_<ic> and that this P_<ic> is utilized to overcome the viscous flow resistance of the intracellular contents during pseudopod formation.