Microwave bioeffects in the erythrocyte are temperature and pO2 dependent: Cation permeability and protein shedding occur at the membrane phase transition

1984 ◽  
Vol 5 (2) ◽  
pp. 283-291 ◽  
Author(s):  
R. P. Liburdy ◽  
A. Penn
Keyword(s):  
Phase Transition ◽  
Membrane Phase ◽  
Cation Permeability ◽  
Protein Shedding

scholarly journals Oscillation and Repetitive Firing in Squid Axons

1970 ◽  
Vol 55 (1) ◽  
pp. 104-118 ◽  
Author(s):  
Rita Guttman ◽  
Robert Barnhill
Keyword(s):  
Phase Transition ◽  
Critical Temperature ◽  
Natural Frequency ◽  
Stimulus Intensity ◽  
Repetitive Firing ◽  
Time Interval ◽  
Membrane Phase ◽  
Temperature Range ◽  
Subthreshold Oscillation ◽  
Low Calcium

Space-clamped squid axons treated with low calcium and computed Hodgkin-Huxley (HH) axons were stimulated by steps of superthreshold current from 101 to 400% of the rheobasic value over a temperature range of 5–27°C. The natural frequency of sustained repetitive firing of real and computed axons depended weakly upon stimulus intensity and strongly upon temperature, with a Q10 of 2.7 (experimental) and 2.6 (computed). For real axons, but not the computed axon, the intervals between the first two spikes were shorter than between subsequent spikes. Constant spike frequencies from 75 Hz at low intensities and temperatures to 330 Hz at high intensities and temperatures were soon achieved. Subthreshold and superthreshold responses were sometimes intermixed in a train of responses from a real axon responding to a constant step of current, but not predicted by HH. The time interval following a spike was always longer than that following a subthreshold oscillation in slightly decalcified real axons, as Huxley and FitzHugh also found for computed axons. There was a bias toward spikes at the beginning of the train and toward subthreshold responses later on. Some repeated patterns were found, every second, third, or fourth response being a spike. Neither the HH equations nor the computed or experimental threshold behaviors show a critical temperature to support a membrane phase transition.

Membrane phase transition of intact human platelets: Correlation with cold-induced activation

1996 ◽  
Vol 168 (2) ◽  
pp. 305-313 ◽  
Author(s):  
Fern Tablin ◽  
Ann E. Oliver ◽  
Naomi J. Walker ◽  
Lois M. Crowe ◽  
John H. Crowe
Keyword(s):  
Phase Transition ◽  
Human Platelets ◽  
Membrane Phase

scholarly journals Fission of Lipid-Vesicles by Membrane Phase Transitions in Thermal Convection

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Patrick W. Kudella ◽  
Katharina Preißinger ◽  
Matthias Morasch ◽  
Christina F. Dirscherl ◽  
Dieter Braun ◽  
...  
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Temperature Gradient ◽  
Temperature Drop ◽  
Lipid Vesicles ◽  
Membrane Phase ◽  
Transition Width ◽  
Shear Forces ◽  
Induced Membrane ◽  
Spherical Vesicles

AbstractUnilamellar lipid vesicles can serve as model for protocells. We present a vesicle fission mechanism in a thermal gradient under flow in a convection chamber, where vesicles cycle cold and hot regions periodically. Crucial to obtain fission of the vesicles in this scenario is a temperature-induced membrane phase transition that vesicles experience multiple times. We model the temperature gradient of the chamber with a capillary to study single vesicles on their way through the temperature gradient in an external field of shear forces. Starting in the gel-like phase the spherical vesicles are heated above their main melting temperature resulting in a dumbbell-deformation. Further downstream a temperature drop below the transition temperature induces splitting of the vesicles without further physical or chemical intervention. This mechanism also holds for less cooperative systems, as shown here for a lipid alloy with a broad transition temperature width of 8 K. We find a critical tether length that can be understood from the transition width and the locally applied temperature gradient. This combination of a temperature-induced membrane phase transition and realistic flow scenarios as given e.g. in a white smoker enable a fission mechanism that can contribute to the understanding of more advanced protocell cycles.

Sign in / Sign up

Export Citation Format

Share Document