Respiratory physiology & neurobiology
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Respir Physiol Neurobiol · Apr 2011
ReviewExperimental protocols and preparations to study respiratory long term facilitation.
Respiratory long-term facilitation is a form of neuronal plasticity that is induced following exposure to intermittent hypoxia. Long-term facilitation is characterized by a progressive increase in respiratory motor output during normoxic periods that separate hypoxic episodes and by a sustained elevation in respiratory activity for up to 90min after exposure to intermittent hypoxia. This phenomenon is associated with increases in phrenic, hypoglossal or carotid sinus nerve inspiratory-modulated discharge. ⋯ Initially, the models and protocols used to study LTF in animals other than humans will be discussed, followed by a section specifically focused on human studies. Each section will begin with a discussion of various factors that must be considered when selecting an experimental preparation and intermittent hypoxia protocol to examine LTF. Model and protocol design recommendations will follow, with the goal of presenting a prevailing model and protocol that will ultimately ensure standardized comparisons across studies.
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Respir Physiol Neurobiol · Apr 2011
Cartography of human diaphragmatic innervation: preliminary data.
In humans, anatomy indicates that the phrenic nerve mainly arises from the C4 cervical root, with variable C3 and C5 contributions. How this translates into functional innervation is unknown. The diaphragm response to electrical stimulation of C3, C4 and C5 was described in three patients undergoing surgical laryngeal reinnervation with an upper phrenic root (surface chest electrodes at anterior, lateral and posterior sites; oesophageal and gastric pressures (Pes and Pga) to derive transdiaphragmatic pressure (Pdi)). ⋯ It produced Pdi values of 9, 11, and 14cmH(2)O in the three patients, respectively, vs. 9, 9, and 7cmH(2)O for C4. C3 stimulation produced modest Pdi responses, whereas C5 stimulation could produce Pdi responses close to those observed with C4 stimulation. These singular observations confirm the dominance of C4 in diaphragm innervation but suggest than C5 can be of importance.