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Morphological changes and membrane potential of human granulocytes under influence of chemotactic peptide and/or
U Jäger1, H Gruler, B Bültmann
1Abteilung für Allgemeine Physiologie, Universität Ulm.
Abstract:
The membrane potential, Em, of human granulocytes (PMNs), was recorded using glass microelectrodes. The membrane potential Em exhibited potential fluctuations accompanied by characteristic changes of cell shape. The periodic potential fluctuations (7-s, 70-s, and 260-s periodicities) ascertained by the autocorrelation technique, suggested the existence of an internal clock. The chemoattractant f-Met-Leu-Phe (FMLP) had no influence on the periodicities, whereas the amplitudes of the fluctuations were increased by it. Treatment of PMNs with Echo 9 virus also resulted in hyperpolarization. The 70-s periodicity disappeared under virus treatment indicating a virus-induced change of the internal program and loss of chemotactic activity.
Insights
Human granulocytes (PMNs) possess an internal biological clock regulating cell shape and membrane potential. Echo 9 virus disrupts this clock, altering cell behavior and reducing chemotactic activity.
Area of Science:
- Cellular biology
- Biophysics
Background:
- Human granulocytes (polymorphonuclear cells, PMNs) play crucial roles in immune responses.
- Cellular membrane potential is a key indicator of cell function and state.
Purpose of the Study:
- To investigate the intrinsic electrical activity and potential fluctuations of human granulocytes.
- To determine the influence of chemoattractants and viral infections on granulocyte membrane potential and periodicity.
Main Methods:
- Recording of membrane potential (Em) in human granulocytes using glass microelectrodes.
- Autocorrelation technique to identify periodic fluctuations in membrane potential.
- Treatment of granulocytes with chemoattractant f-Met-Leu-Phe (FMLP) and Echo 9 virus.
Main Results:
- Human granulocytes exhibit periodic membrane potential fluctuations (7-s, 70-s, 260-s) suggesting an internal biological clock.
- FMLP increased fluctuation amplitudes but did not alter periodicities.
- Echo 9 virus caused hyperpolarization and abolished the 70-s periodicity, impairing chemotactic activity.
Conclusions:
- Human granulocytes possess an endogenous time-keeping mechanism reflected in membrane potential oscillations.
- Viral infection can disrupt this internal clock, leading to altered cellular function and loss of chemotaxis.