Electrophysiology preparation

Martin, R.J. (1995) An electrophysiological preparation of Ascaris suum pharyngeal muscle reveals a glutamate-gated chloride channel sensitive to the avermectin analogue milbemycin D. Parasitology 112, 252. 

A variety of different types of tissue preparation are used to study neurosecretion and synaptic transmission. A classical preparation is the frog NMJ (discussed below). The brain slice has been used for many years for biochemical studies of CNS metabolism and is a useful preparation for electrophysiological studies of synaptic transmission in the CNS. Slices can be oriented to maintain the local neuronal circuitry and can be thin, 0.3 mm, to minimize anoxia. The transverse hippocampal slice is widely used as an electrophysiological preparation to study synaptic plasticity (see Ch. 53). Primary cultures of neurons from selected CNS areas and sympathetic ganglia are also frequently used. They permit excellent visual identification of individual neurons and control of the extracellular milieu, but the normal neuronal connections are disrupted. 

The avermectins have been shown to increase chloride conductance in invertebrate electrophysiological preparations (J, JA,25) and modulate the binding of several GABA receptor-ionophore ligands (9, 10), but the molecular mechanisms underlying their neurotoxicity remain poorly defined. Recently, Abalis e t al. (1 ) reported an avermectin Independent stimulation of chloride uptake in rat brain vesicles tnat... 

Amino acids which were non-stimulatory in the electrophysiological preparation also failed to elicit feeding responses in separate behavioral experiments, whereas stimulatory amino acids did elicit feeding in the behavioral experiments. 

Additionally, the electrophysiological effects are often obtained from normal myocardial preparations and the abnormalities of cellular electrophysiology which cause arrhythmias in a diseased myocardium may be uniquely related to the disease process (10). Nevertheless, antiarrhythmic agent classifications have been useful as a mnemonic device. 

Electrophysiological Experiments. Guinea pig myocardial cells prepared as described previously 24) were superfused at 37 C with a Tyrode solution. Electrical properties of the myocytes were examined by the patch-clamp methods (25) using fire-polished pipettes. The current was measured by means of a patch-clamp amplifier, stored on the tape through a digital PCM data recording system, and analyzed with a computer. 

Sieep electrophysiology To date, four studies have been published that examine the effects of valerian on human sleep and its electrophysiology, which have produced variable results. An early study (Muller-Limmroth and Ehrenstein 1977) showed that a combined preparation of valerian and hops in sleep-disturbed subjects increased the amount of slow-wave and REM sleep. Another study using an aqueous extract (400 mg) of valerian did not show significant EEG effects, but suggested a relation between the EEG effects and subjective effects, that is, shortened sleep... 

In electrophysiological studies aimed at elucidating the mechanism of action of kappa agonists, U-50488 has been shown to depress excitatory post-synaptic potentials in a rat locus coeruleus preparation, which indicates that it acts presynaptically to inhibit transmitter release [38]. Also, in spinal cord slice preparations from the 9-16-day-old rat, U-69593 (9) produced a naloxone-reversible depression of spontaneous and electrically evoked activity in dorsal horn neurones [39],... 

A structurally novel series of substituted 10//-benzo[4,5]furo[3,2- ]indole-l-carboxylic acids 504-507 was prepared and shown to possess potent, bladder-selective smooth muscle relaxant properties and thus is potentially useful for the treatment of urge urinary incontinence. Electrophysiological studies using rat detrusor myocytes have demonstrated that prototype compound 8 produces a significant increase in hyperpolarizing current, which is iberiotoxin (IbTx)-reversed, thus consistent with activation of the large-conductance Ca -activated potassium channel (BKca) <2001BML2093>. 

When I started as a novice in the field of cardiac electrophysiology, the dogma was that gap junctions are specialized membrane structures present in the cardiac and smooth muscle of vertebrates where they serve to propagate the action potential from cell to cell. Purkinje fibers and muscular trabeculae were the preferred cardiac preparations. These multicellular preparations were suitable to perform cable analyses and diffusion studies. At that time, my mentor, Silvio Weidmann, had already accomplished his elegant functional studies. 

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