Potentials, electric miniature

Stimulation of the motoneuron releases acetylcholine onto the muscle endplate and results in contraction of the muscle fiber. Contraction and associated electrical events can be produced by intra-arterial injection of ACh close to the muscle. Since skeletal muscle does not possess inherent myogenic tone, the tone of apparently resting muscle is maintained by spontaneous and intermittent release of ACh. The consequences of spontaneous release at the motor endplate of skeletal muscle are small depolarizations from the quantized release of ACh, termed miniature endplate potentials (MEPPs) [15] (seeCh. 10). Decay times for the MEPPs range between l and 2 ms, a duration similar to the mean channel open time seen with ACh stimulation of individual receptor molecules. Stimulation of the motoneuron results in the release of several hundred quanta of ACh. The summation of MEPPs gives rise to a postsynaptic excitatory potential (PSEP),... 

Electrochemical devices have proven very useful for sequence-specific biosensing of DNA. Electrochemical detection of DNA hybridization usually involves monitoring a current response under controlled potential conditions. The hybridization event is commonly detected via the increased current signal of a redox indicator (that recognizes the DNA duplex) or from other hybridization-induced changes in electrochemical parameters (e.g., conductivity or capacitance). Modern electrical DNA hybridization biosensors and bioassays offer remarkable sensitivity, compatibility with modern microfabrication technologies, inherent miniaturization, low cost (disposability), minimal power requirements, and independence of sample turbidity or optical pathway. Such devices are thus extremely attractive for obtaining the sequence-specific information in a simpler, faster, and cheaper manner, compared to traditional hybridization assays. 

In an effort to reduce the noise problems often encountered during in vivo type measurements (which limit the reliability of the final determination), telemetry-type systems have been proposed (Bl). In this approach the implanted catheter is connected to a miniature radio transmitter which transmits the in vivo ISE cell potentials to a receiving unit placed far from the patient or animal. By replacing the wires normally required to transmit the potential information to the external instrument, far less interference from environmental and electrical noise normally found in rooms used for surgical procedures occurs. This approach appears to hold great promise for the future of in vivo ion and gas monitoring with ISEs. 

In a more recent approach, the streaming potential in a miniature column containing immobilized biosorbent has been evaluated (Matti-asson, 1984 Glad et al., 1986). The interaction between the sorbent and the analyte could be indicated via the change of the charge distribution within the electrical double layer caused by the biospecific binding. Carbohydrates have been determined with this sensor system by using con A. 

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