Transmembrane potential system

Much progress has been made in understanding the different mechanisms that can cause mitochondrial dysfunction, such as (i) uncoupling of electron transport from ATP synthesis by undermining integrity of inner membrane (ii) direct inhibition of electron transport system components (iii) opening of the mitochondrial permeability transition pore leading to irreversible collapse of the transmembrane potential and release of pro-apoptotic factors (iv) inhibition of the... 

Figure 4. Effect of kmophores (A) and transmembrane potentials (B) on quantum yield of heptylviologen reduction in the vesicle system where 4 is the quantum yield. CCCP (carbonyl cyanide m-chlorophenylhydrazone) is the H carrier, and valino-mycin is the K carrier gramicidin makes the membrane permeable for cations such...

Since mitochondrial morphology remains intact throughout apoptosis, until recently, mitochondria were not assumed to be critical players in the effecter phase of apoptosis. But accumulating evidence indicates that mitochondria exhibit major functional roles and structural changes that serve to regulate apoptosis. Data from diverse models systems conclude that (1) collapse of mitochondrial inner transmembrane potential (A Pm), (2) mitochondrial... 

Use of a high field to activate a membrane enzyme was first reported by Witt et al. (25) in 1976. They used dc pulses of approximately 1 kV/cm and of 1-ms duration to induce ATP synthesis by the chloroplast ATPase. Following this initial work, there have been many reports on 1-kV/ cm dc field-induced ATP synthesis in different ATP synthetic systems (see the literature cited in references 13 and 14). The main conclusion from these studies is that an applied field-induced transmembrane potential can facilitate ATP release from the enzyme whether a PEF can affect enzyme turnover is not clear. Because 1-kV/ cm dc fields also cause severe Joule heating of a sample suspension, thermal effects cannot be easily avoided except when very short electric pulses (microseconds) are used. Thus, the method has limited utility for electroactivation experiments. The PEF method is, however, quite popular for the study of electroporation and electrofusion of cell membranes (see the chapter by J. Weaver in this volume), electroinsertion of membrane proteins (26), and electrotransfection of cells (27). 

The results of the investigations of transmembrane potentials in this system under various conditions are given below in Sections 5-9. However, first it would be more reasonable to consider a simpler chain. 

Flavine mononucleotide (FMN) forms a part of the first complex of the respiratory chain of mitochondria, and its effect on the transmembrane potential value during redox reactions in the system NADH-Q6-O2 was shown by Ismailov et al. taking as an example bilayer lipid membranes.54 55 57,75... 

But before passing on to the complete system (2), it is necessary to understand how flavine mononucleotide affects the transmembrane potential and the conductivity of the bilayer. 

Figure 7 shows the dependence of the transmembrane potentials on the FMN content in the system... 

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