Electrical stimulations

Arrhythmias. The first solution to cardiovascular problems arising from arrhythmias came about as a result of a complication caused by open-heart surgery. During procedures to correct congenital defects in children s hearts, the electrical conduction system often became impaired, and until it healed, the heart could not contract sufficiently without outside electrical stimulation. A system that plugged into a wall outlet was considered adequate until an electrical storm knocked out power, lea ding to the development of the first battery-powered external pacemaker. 

Cardiomyopathy. The best available solution to cardiomyopathy may be one that is less sophisticated than transplant surgery or the artificial heart. The cardiomyoplasty-assist system combines eariier electrical stimulation technology with a new surgical technique of utilizing muscle from another part of the body to assist the heart. 

Dia2epam [439-14-5] (60) and clona2epam [1622-61 -3] (61) suppress cough induced by electrical stimulation of the lower brainstem of cats (90). Clona2epam and dia2epam adrninistered intravenously are about thirty-five times and six times more potent than codeine, respectively. Nevertheless, the compounds have not been widely used as antitussives in humans. Dia2epam is used in the treatment of anxiety, and clona2epam as an anticonvulsant. 

The myocytes of smooth muscle are approximately 100 to 500 p,m in length and only 2 to 6 p,m in diameter. Smooth muscle contains very few t-tubules and much less SR than skeletal muscle. The Ca that stimulates contraction in smooth muscle cells is predominantly extracellular in origin. This Ca enters the cell through Ca channels in the sarcolemmal membrane that can be opened by electrical stimulation, or by the binding of hormones or drugs. The contraction response time of smooth muscle cells is very slow compared with that of skeletal and cardiac muscle. 

Extraction and purification of Diplocardia luciferase (Bellisario et al., 1972). About 50 specimens of Diplocardia longa (widespread in southern Georgia about 30 cm in length) were electrically stimulated in 250 ml of 0.1 M EDTA at 4°C to exude coelomic fluid. The suspension of coelomic cells obtained was centrifuged at 480 g for 5 min. The pellets from 200 worms were combined and an acetone powder was prepared. The acetone powder obtained (about 10 g) was stable at -80°C for at least one year. 

The lateral hypothalamic area has been identified as a feeding centre by studies involving electric stimulation and discrete lesions. Neurons in the lateral hypothalamic area and the neighbouring perifornical area express neuropeptides that stimulate feeding when injected into cerebral ventricles (orexins 1 and 2, melanin-concentrating hormone (MCH)). 

In 1954, experiments by Olds and Milner revealed that the brain has specialized centers for reward functions. In these studies electrical stimulation of certain brain sites was found to be highly rewarding in the sense that rats operantly respond for electrical stimulation of these brain sites, often to the exclusion of any other activity. A neurotransmitter system that is particularly sensitive to electrical self-stimulation is the mesolimbic dopamine projection that originates in the ventral tegmental area and projects to structures closely... 

Figure 3. Top panel Whole muscle force (x) and single fiber PCr (a, a) and ATP ( , ) concentrations at rest and after 10 and 20 sec of intermittent electrical stimulation at 50 Hz. Open symbols denote type I fibers closed symbols denote type II fibers. Bottom panel Glycogenolytic rates in type I and II fibers during the 20 sec stimulation period. The open bar denotes type I fibers the closed bar denotes type II fibers.

This section examined small muscle preparations stimulated electrically or skinned muscle fibers maintained in superfused baths with different substance concentrations. The electrical stimulation was either continuous or intermittent for relatively short durations. 

Bergstrom, M. Hultman. E. (1990). Contraction characteristics of the human quardriceps muscle during percutaneous electrical stimulation. Pflugers Arch. 417, 136-141. 

Hultman, E. Sjoholm, H. (1983b). Electromyogram, force and relaxation time during and after continuous electrical stimulation of human skeletal muscle in situ. J. Physiol. 339, 33-40. 

Hultman, E. Spriet, L.L. (1986). Skeletal muscle metabolism, contraction force and glycogen utilization during prolonged electrical stimulation in humans. J. Physiol. 374,493-501. 

Spriet, L.L., Soderlund, K., Bergstrom, M., Hultman, E. (1987a). Anaerobic energy release in skeletal muscle during electrical stimulation in men. J. Appl. Physiol. 62, 611-615. 

Liquid crystalline elastomers (LCEs) are composite systems where side chains of a crystalline polymer are cross-linked. Their mesogenic domains can be ordered nematically and undergo a phase transition to a disordered state at a temperature well above the glass-transition temperamre (Tg) of the polymer. Although the phase transition is thermally driven, LCEs demonstrate electrical conductivity and thus can be electrically stimulated." Ratna" has reported contractions of nearly 30% due to the phase transition of acrylate-based LCEs. 

The presence of toxins in C. geographus venom which block the response of vertebrate skeletal muscle to direct electrical stimulation was first detected by Endean et al. (14). A toxic component which reversibly blocked the generation of action... 

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