Electroimmunology: membrane potential, ion-channel activities, and stimulatory signal transduction in human T lymphocytes from young and elderly.
There are conflicting data on the functional role and direction of the changes in membrane potential and ion currents accompanying lymphocyte stimulation. Recently, we discovered that a known sodium channel opener, bretylium tosylate (BT), may influence the stimulatory processes of lymphocyte activation at more than one site. Parallel flow cytometric and electrophysiological measurements with patch clamp techniques showed that BT quickly repolarizes previously slightly depolarized human peripheral blood as well as splenic murine lymphocytes. The repolarization occurred through opening ligand- and voltage-gated, hitherto unknown sodium channels, and the sodium influx activated Na(+)-K(+)-dependent, electrogenic ATP-ase activity. A comparison of the flexible responsiveness of the membrane potential was carried out between lymphocytes from young and elderly using the above mechanism and a number of combinations of channel blockers and ionophores in order to obtain information on the alleged changes in immunological behavior. A significant difference has been found between lymphocytes from human young and elderly volunteers in the readiness to respond to channel-activating perturbations. An explanation is offered, based upon known physicochemical changes in the plasma membrane during aging.
Damjanovich
S
S
Department of Biophysics, University Medical School of Debrecen, Hungary.
Pieri
C
C
D000328:Adult; D000367:Age Factors; D000368:Aged; D000375:Aging / Q000276:immunology*; D002462:Cell Membrane / Q000276:immunology / Q000502:physiology; D006801:Humans; D007473:Ion Channels / Q000502:physiology*; D008564:Membrane Potentials; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000276:immunology / Q000502:physiology*
D007473:Ion Channels