BACKGROUND： Nikethamide, a respiratory center stimulant, is widely used in China. However, its effects on the central nervous system and medullary respiratory center remain poorly understood. OBJECTIVE： To investiga...BACKGROUND： Nikethamide, a respiratory center stimulant, is widely used in China. However, its effects on the central nervous system and medullary respiratory center remain poorly understood. OBJECTIVE： To investigate the influence of nikethamide on inspiratory neuron discharge in the medial region of the nucleus retrofacialis in neonatal rats, based on the observations addressing rhythmic respiratory discharge generated by the basic medullary respiratory center and various respiration neuron discharges in brain slices. DESIGN, TIME AND SETTING： A controlled, observational study utilizing in vitro neuroelectrophysiology was performed at the Department of Physiology in Southern Medical University between September and December in 2007. MATERIALS： Nikethamide was purchased from Sigma, USA; BL-420E biological signal collection and manaclement system was provided by Chengdu TME Technology, China.METHODS： Isolated medulla-spinal cord preparations were collected from neonatal Sprague Dawley rats, aged 1-3 days. Tissues were divided to include the medial region of the nucleus retrofacialis, ventral respiratory, and dorsal respiratory groups. Subsequently, modified Kreb＇s solution and 5 μg/mL nikethamide-containing modified Kreb＇s solution were consecutively perfused into the medial region of the nucleus retrofacialis in neonatal rat brain slices. MAIN OUTCOME MEASURES： Hypoglossal nerve root respiratory-related rhythmic discharge activities and inspiratory neuron discharges were recorded with an adsorption electrode and microelectrode. RESULTS Nikethamide resulted in prolonged inspiratory neuron discharge time, shortened respiratory cycle and expiratory time. Nikethamide intervention resulted in enhanced integral amplitude of some inspiratory neurons with no changes in discharge frequency or increased discharge frequency in remaining inspiratory neurons with no changes in integral amplitude. CONCLUSION： Nikethamide excites inspiratory neurons in the basic rhythmic respiration and medullary respiratory center, in addition to increased inspiratory neuron and neural network excitability.展开更多
Domestic application of infrared patch clamp techniques on brain slices is limited.The key of the tech-nique is to prepare high-quality brain slices.The present paper describes the preparation procedure of brainstem s...Domestic application of infrared patch clamp techniques on brain slices is limited.The key of the tech-nique is to prepare high-quality brain slices.The present paper describes the preparation procedure of brainstem slices and the spontaneous firing properties of rat medial vestibular nucleus(MVN)neurons.By infrared differ-ential interference contrast technique,neurons of rat MVN were visualized directly at the depth of 50–100 mm underneath the surface of slices.Firing activities of MVN neurons were recorded by the whole-cell patch clamp technique in artificial cerebrospinal fluid(ACSF)and low Ca^(2+)-high Mg^(2+) fluid.The firing mode was more irregular and depressive in low Ca^(2+)-high Mg2+fluid than in ACSF.According to the averaged waveform of action potentials,cells were classified as the neurons with mono-phasic after-hyperpolarization potential(AHP),and the neurons with biphasic AHP.The resting membrane potential(RMP),input resistance(Rin)and membrane capacitance(Cm)of neurons were recorded and com-pared between groups.With infrared videomicroscopy,patch clamp recordings could be made under direct obser-vation in freshly prepared brainstem slices.The discharge activities of MVN neurons were spontaneous and the fir-ing mode was modulated by extracellular calcium concen-tration.The basic membrane properties of two types of neurons were not significantly different,while the differ-ences in waveform might play a role in the segregation between tonic and kinetic cells.展开更多
基金the National Natural Science Foundation of China,No.30570670the Natural Science Foundation of Guangdong Province,No.5004714
文摘BACKGROUND： Nikethamide, a respiratory center stimulant, is widely used in China. However, its effects on the central nervous system and medullary respiratory center remain poorly understood. OBJECTIVE： To investigate the influence of nikethamide on inspiratory neuron discharge in the medial region of the nucleus retrofacialis in neonatal rats, based on the observations addressing rhythmic respiratory discharge generated by the basic medullary respiratory center and various respiration neuron discharges in brain slices. DESIGN, TIME AND SETTING： A controlled, observational study utilizing in vitro neuroelectrophysiology was performed at the Department of Physiology in Southern Medical University between September and December in 2007. MATERIALS： Nikethamide was purchased from Sigma, USA; BL-420E biological signal collection and manaclement system was provided by Chengdu TME Technology, China.METHODS： Isolated medulla-spinal cord preparations were collected from neonatal Sprague Dawley rats, aged 1-3 days. Tissues were divided to include the medial region of the nucleus retrofacialis, ventral respiratory, and dorsal respiratory groups. Subsequently, modified Kreb＇s solution and 5 μg/mL nikethamide-containing modified Kreb＇s solution were consecutively perfused into the medial region of the nucleus retrofacialis in neonatal rat brain slices. MAIN OUTCOME MEASURES： Hypoglossal nerve root respiratory-related rhythmic discharge activities and inspiratory neuron discharges were recorded with an adsorption electrode and microelectrode. RESULTS Nikethamide resulted in prolonged inspiratory neuron discharge time, shortened respiratory cycle and expiratory time. Nikethamide intervention resulted in enhanced integral amplitude of some inspiratory neurons with no changes in discharge frequency or increased discharge frequency in remaining inspiratory neurons with no changes in integral amplitude. CONCLUSION： Nikethamide excites inspiratory neurons in the basic rhythmic respiration and medullary respiratory center, in addition to increased inspiratory neuron and neural network excitability.
基金supported by the National Natural Science Foundation of China(Grant No.30371525)the National Science Foundation for Distinguished Young Scholars of China(No.39925035)the National Science&Technology Pillar Program in the Eleventh Five-year Plan Period(No.2007BAI18B13).
文摘Domestic application of infrared patch clamp techniques on brain slices is limited.The key of the tech-nique is to prepare high-quality brain slices.The present paper describes the preparation procedure of brainstem slices and the spontaneous firing properties of rat medial vestibular nucleus(MVN)neurons.By infrared differ-ential interference contrast technique,neurons of rat MVN were visualized directly at the depth of 50–100 mm underneath the surface of slices.Firing activities of MVN neurons were recorded by the whole-cell patch clamp technique in artificial cerebrospinal fluid(ACSF)and low Ca^(2+)-high Mg^(2+) fluid.The firing mode was more irregular and depressive in low Ca^(2+)-high Mg2+fluid than in ACSF.According to the averaged waveform of action potentials,cells were classified as the neurons with mono-phasic after-hyperpolarization potential(AHP),and the neurons with biphasic AHP.The resting membrane potential(RMP),input resistance(Rin)and membrane capacitance(Cm)of neurons were recorded and com-pared between groups.With infrared videomicroscopy,patch clamp recordings could be made under direct obser-vation in freshly prepared brainstem slices.The discharge activities of MVN neurons were spontaneous and the fir-ing mode was modulated by extracellular calcium concen-tration.The basic membrane properties of two types of neurons were not significantly different,while the differ-ences in waveform might play a role in the segregation between tonic and kinetic cells.
