Journal of neuroscience methods
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J. Neurosci. Methods · Jan 2007
Non-invasive intraoperative monitoring of blood pressure and arterial pCO2 during surgical anesthesia in mice.
Despite the constantly increasing use of genetically engineered mice in biomedical research, control of crucial physiological parameters such as blood pressure and arterial blood gases is difficult to achieve in temporarily anesthetized mice due to lack of techniques for reversible arterial cannulation. Here we report that arterial blood pressure and blood gases can be measured reliably in anaesthetized and artificially ventilated mice using non-invasive technology. C57Bl6 mice were anaesthetized by i.p. injection of midazolam, fentanyl, and medetomidin, intubated, and ventilated for 3h. ⋯ Non-invasive blood pressure (NIBP) correlated strongly with the invasive arterial blood pressure measured at the external carotid artery (r = 0.99, P < 0.001) and end tidal pCO2 values correlated very well with arterial blood pCO2 (r = 0.93, P < 0.001). The current results demonstrate that it is possible to reliably measure and control the most relevant physiological parameters in anesthetized mice. Thereby the current study may help to reduce animal numbers and perform mice experiments under more defined and controlled physiological conditions in the future.
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J. Neurosci. Methods · Jan 2007
Two-dimensional spatial distribution of surface mechanomyographical response to single motor unit activity.
In order to better understand the mechanisms of generation of mechanomyography (MMG) signals, the two-dimensional distribution of surface MMG produced by the activity of single motor units was analyzed by a novel two-dimensional recording method. Motor unit action potentials were identified from intramuscular electromyographic (EMG) signals and used to trigger the averaging of MMG signals detected over the tibialis anterior muscle of 11 volunteers with a grid of 5x3 accelerometers (20-mm inter-accelerometer distance). The intramuscular wires were inserted between the first and second accelerometer in the middle column of the grid, proximal to the innervation zone. ⋯ The double integrated signals (muscle displacement) indicated negative deflection in the lateral part and inflation close to the tibia bone. The maps of acceleration showed spatial dependency in single motor unit MMG activities. The technique provides a new insight into motor unit contractile properties.