Ein Analogrechenverfahren zur Analyse biologischer Anpassungsvorgänge mit der Methode der Thermodynamik irreversibler Prozesse

Abstract

By means of theoretical considerations concerning functional biological adaptations, attempts have been made (1) to explain these adaptations on the basis of transitional flux equilibria of cellular metabolic energy processes, (2) to obtain a comprehensive description using transport equations of irreversible thermodynamics, and (3) to analyse the adaptations on the basis of metabolic feed-back system. An analogue computer was used for mathematical calculations. The model of a biological reaction train was set up using a 4-pol system with series of coupled RC-members. Substrate concentrations or driving forces were represented as potentials, velocity constants as conductances or reciprocal time constants, and substrate- or energy fluxes as electric currents. Taking into consideration metabolic feed-back systems, it has been shown that all five types of the temperature-capacity adaptation can be explained on the basis of energetic steady state transitions and may be analysed qualitatively and quantitatively using thermodynamics of irreversible processes. Based on experimental calculations with this model, specific biological investigations of the temperature-capacity adaptation of frog heart rate were untertaken. The experimental results obtained agree well with the theoretical predictions from the model, proving the fundamental value of the application of analogue computer models for solving biological problems. Finally, the possibilities of such elementary energetic cell models, if used as receptor- or neuronmodels in the field of neurophysiology, are discussed, and an example is given. Together with methods of the thermodynamics of irreversible processes, analogue models have also proven useful for solving problems of the biological information theory.

Zusammenfassung

1. Biologische Anpassungsvorgänge sind aus den Grundeigenschaften des Zellstoffwechsels zu erklären. Dabei können sowohl primäre Regulationen über Fließgleichgewichtsveränderungen und auch sekundäre Regulationen über Rückkoppelungsmechanismen des Stoffwechsels wirksam sein.

2. Anpassungsvorgänge sind über elektrische Analogschaltbilder von Stoffwechselzügen zu simulieren. Sie lassen sich qualitativ und quantitativ durch Transportgleichungs-systeme der Thermodynamik irreversibler Prozesse beschreiben und analysieren.

3. Die Anwendung von Analogmodellen thermodynamisch offener biologischer Systeme hat heuristischen Wert für den gezielten Ansatz experimenteller Versuche an lebenden Objekten.