Biomedical subjects

E Zothner

Publications and source records attributed to E Zothner.

4 recordsLinked to original sources

PubMed1979

Temperature dependence on the passive and dynamic electrical parameters of muscle cells.

Measurements of the temperature dependence in the range from 10 C to 30 C on the passive and dynamic electrical properties of single frog muscle cell following Arrhenius relation have been made. The propagated responses (V-t) and conduction velocity theta were analyzed following the H-H propagated cable equation. The ionic current-membrane potential relationship (I-t) was calculated from the phase-plane trajectory analysis (V-V) of the action potential curve (V-t). All the rate and time constants of the excitation and propagation processes kr, kNa, kK, tau Na, tau K, the negative conductance (-gNa) and the ionic conductances gNa, gK, influencing the evolution of the curves (V-t), (V-V) and (I-V) are correlated. The magnitudes of the resting (Vr) and action potential amplitude (Vs), the excitation potential (V*), the negative after potential (Vn), and the sodium equilibrium potential (VNa); the magnitudes of the maximum rate of rise and fall of the spike (V+) and (V-) and those corresponding to the inward INa and outward IK ionic currents, were analyzed. Two general classes of findings were obtained. One group of action potential parameters theta, V+, V-, Vn, kr, kNa, kK, tau Na, tau K, -gNa, gNa, gK, INa and IK is strongly temperature dependent with Q 10 S approximately 2 and energy of activation E approximately 10 kcal/mole. The other group of parameters, Gm (passive conductance), Cm (capacitance), tau, Vr, V*, Vs, and VNa are slightly temperature dependent, with Q10's lower than 1.4. This study contributes deeply to the analysis of temperature effects on the electrical cell responses to adequate stimuli. This temperature dependence analysis was designed to detect possible "masked" actions of microwave radiation on cell membrane functions.

Action Potentials↗

PubMed1979

Quantitation of chronic microwave radiation effects on muscle cell electrical excitable properties: a temperature dependence analysis of the H-H cable and membrane current parameters of irradiated cells.

Frogs Rana pipiens maintained under constant laboratory environmental conditions were subjected daily to chronic microwave exposure with pulsed microwave (2.88 GHZ) at a power density of 10 mW/cm2, during 0.1 hour, for periods up to 100 days. The whole body Specific Absorption Rate (SAR) was of 1.5 mW/g per 1 mW/cm2. The passive and dynamic electrical parameters of sartorius muscle cells from control and irradiated frogs as a function of temperature in the range from 10 C to 30 C, have been analyzed. This temperature dependence analysis, presented in another work, was planned to be used in this paper for detecting those possible "masked" chronic microwave effects in complex membrane mechanisms highly temperature sensitive, and tightly related to the excitation and propagation of bioelectrical responses. The temperature dependence of the passive (Vr, Gm, Cm, and tau) and the active cell electrical parameters (theta, V*, Vs, VNa, Vn, V+, V-, kr, kNa, kK, tau Na, tau K, -gNa, gNa, gK, INa, and IK) was not altered by chronic microwave exposure. The striking observation reported in another work, about the presence of two groups of cell electrical parameters, characterized by their dependence with temperature, was reproduced on the irradiated muscle cells. Results have indicated that there was not muscle cell cumulative bioeffects resulting from microwave exposure to 10 mW/cm2, over a 0.1 hour period.

Action Potentials↗

PubMed1978

Digital interface for bioelectrical data acquisition system.

The action potential digitalized and stored by means of a fast solid state electronic waveform recording system (Digitalizer) can be directly read out on a printer or in a computer for further processing. It has been designed a digital interface allowing the automatization of these bioelectrical data acquisition and printing process.

Action Potentials↗

PubMed1978

Digitalizer system and memory for electric transients.

It was designed a fast solid state electronic waveform recording system (Digitalizer), which can record, store and display action potentials or any type of event, either single pulse or repetitive, as a function of time. Above all, its capacity to record fast transients and to give the output in analog and digital form, makes this electronic device more convenient that conventional recorders or single trace oscilloscope systems.

Action Potentials↗