Slow-wave potentials

Compare and contrast pacemaker and slow-wave potentials... 

Slow-wave potentials also involve gradual depolarization of the cell membrane, but these depolarizations do not necessarily reach threshold. Therefore, the depolarization may simply be followed by repolarization back to the initial membrane potential. These slow "wave-like" potentials occur rhythmically and do not lead to smooth muscle contraction. The peak-to-peak amplitude of the slow-wave potential is in the range of 15 to 30 mV. Therefore, under the appropriate conditions, the depolarization phase of the slow-wave potential may, in fact, reach threshold. When this occurs, a burst of action potentials is generated, resulting in muscle contraction. 

The mechanism of the slow-wave potential is unclear. One hypothesis is that the rate at which sodium ions are actively transported out of the cell rhythmically increases and decreases. A decrease in the outward movement of Na+ ions allows positive charges to accumulate along the internal surface of the cell membrane and depolarization takes place. This is followed by an increase in the outward movement of Na+ ions, which causes the internal surface of the cell membrane to become more negative, and repolarization takes place. 

Smooth muscle Slow wave potential changes Pacemaker activity for Myogenic rhythm... 

In the controlled (constant) potential method the procedure starts and continues to work with the limiting current iu but as the ion concentration and hence its i, decreases exponentially with time, the course of the electrolysis slows down quickly and its completion lags behind therefore, one often prefers the application of a constant current. Suppose that we want to oxidize Fe(II) we consider Fig. 3.78 and apply across a Pt electrode (WE) and an auxiliary electrode (AE) an anodic current, -1, of nearly the half-wave current this means that the anodic potential (vs. an RE) starts at nearly the half-wave potential, Ei, of Fe(II) - Fe(III) (= 0.770 V), but increases with time, while the anodic wave height diminishes linearly and halfway to completion the electrolysis falls below - / after that moment the potential will suddenly increase until it attains the decomposition potential (nearly 2.4 V) of H20 -> 02. The way to prevent this from happening is to add previously a small amount of a so-called redox buffer, i.e., a reversible oxidant such as Ce(IV) with a standard... 

Fry But ion channels don t always have to generate action potentials to be useful. You measured them as an expression of an action potential, but they might produce slow waves and still produce a function. 

The outcome of the competition is represented in Fig. 5 in terms of the location of the half-wave potential of the RX reduction wave (i.e. the current-potential curve), relative to the standard potential of the RX/ RX- couple, E° (Andrieux et al., 1978). As concerns the competition, three main regions of interest appear in the diagram. On the left-hand side, the follow-up reaction is so slow (as compared to diffusion) that the overall process is kinetically controlled by the parameter A, i.e. by electron transfer and diffusion. Then, going upward, the kinetic control passes from electron transfer to diffusion. In the upper section d in the lower section... 

The rotating disc electrode is constructed from a solid material, usually glassy carbon, platinum or gold. It is rotated at constant speed to maintain the hydrodynamic characteristics of the electrode-solution interface. The counter electrode and reference electrode are both stationary. A slow linear potential sweep is applied and the current response registered. Both oxidation and reduction processes can be examined. The curve of current response versus electrode potential is equivalent to a polarographic wave. The plateau current is proportional to substrate concentration and also depends on the rotation speed, which governs the substrate mass transport coefficient. The current-voltage response for a reversible process follows Equation 1.17. For an irreversible process this follows Equation 1.18 where the mass transfer coefficient is proportional to the square root of the disc rotation speed. 

Another controversial but exciting area of research is the potential role of serotonin in sleep. 5-Hydroxytryptamine may trigger slow-wave sleep (non-REM sleep), whereas the muscarinic AChR and NE are involved in REM sleep (rapid-eye-movement sleep, paradoxical sleep, dream sleep). In addition to the aminergic regulation of sleep, recent research has identified several other presumed sleep factors delta-sleep-inducing peptide, sleep-promoting substance, interleukin-1, and muramyl peptides. 

Examination of Eqs. (54) shows that, within the quantum representation III, the excitation of the fast mode displaces the origin of the slow mode wave functions toward shorter lengths. That may be viewed as a translation of the slow mode potential, that is induced by the excitation of the fast mode. In order to visualize this potential displacement, it is suitable to consider the potential as Morse-like. That is depicted on the right-hand side of Fig. 2. Here, the left-hand side is devoted to the quantum representation //, where there is no potential... 

As a consequence of the translation of the origin of the slow mode potential induced by the excitation of the fast mode, there are in representation ///, overlaps between the wave functions of the H-bond bridge corresponding, respectively, to the ground state of the fast mode and to its first excited state, that is,... 

The reflex doctrine could not, however, help the pioneer sleep and dream scientists very much, because no link could be established between the activity of circuits of neurons (neuronal circuits) and the EEG. It had long been assumed that the EEG was the register of voltage changes in the brain (i.e. cerebral action potentials), although this could not explain the patterns of the EEG seen in sleep (e.g. spindles and slow waves), unless neuronal activity was continuous, i.e. spontaneous, as well as reflexive. Consequently, work at the cellular and EEG levels proceeded along entirely separate but parallel tracks, similar to those that Descartes thought God had used to set mind and body in perfect but independent motion. Cartesian duality dies slowly it is still alive and well in most of us because we cannot yet see how a physical object, the brain, can have subjective experience. This is the so-called hard problem of philosophy. 

Ogura C, Nageishi Y, Matsubayashi M, Omura F, Kishimoto A, et al. 1991. Abnormalities in event-related potentials, N100, P200, P300 and slow wave in schizophrenia. Jpn J Psychiatry Neurol 45 57-65. 

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