Role of reactive oxygen species in regulation of respiratory rhythm in medial area of nucleus retrofacialis / 第二军医大学学报

Objective: To explore the role of reactive oxygen species (ROS, i. e, H2O2 and O2-) in regulation of respiratory rhythm in the medial area of nucleus retrofacialis (mNRF). Methods: Medullary slices of neonatal SD rats, including hypoglossal nerve (XII n) and mNRF, were made according to Suzue's method. Simultaneous recording of the XII n respiratory rhythmic activity (RRA) with suction electrode and the respiratory neuronal discharge were performed with whole cell patch in the mNRF on the brainstem slice in vitro. The effect of t-butyl hydroperoxide (tBHP) and α-lipoic acid (α-LA) on the respiratory pacemaker neurons and respiratory rhythm in the mNRF were observed. Results: tBHP significantly decreased respiratory cycle (RC) and increased respiratory amplitude; α-LA significantly increased RC and decreased its amplitude. Meanwhile, α-LA significantly prolonged the action potential of the respiratory cadmium-insensitive pacemaker neurons and reduced its amplitude, but it had no significant effect on the cadmium-sensitive respiratory pacemaker neurons. Voltage steps and ramps showed that α-LA inhibited both the transient and persistent sodium current of cadmium-insensitive pacemaker neurons. Conclusion: ROS has an excitatory effect on the respiratory rhythm and the cadmium-insensitive respiratory pacemaker neurons through modulating sodium current.

Identification and classification of respiratory pacemaker neurons in the medial region of nucleus retrofacialis in neonatal rats / 生理学报

The aim of the present study is to supply direct experimental proof that the medial region of nucleus retrofacialis (mNRF) is the site generating basic rhythm of respiration. Medullary slices of neonatal Sprague-Dawley rats, including hypoglossal nerve root and mNRF, were made according to Suzue's method. Simultaneous recordings of the respiratory rhythmic discharge activity (RRDA) in hypoglossal nerve root with suction electrode and the respiratory neuronal discharge in the mNRF with whole cell patch clamp were performed on the brainstem slice in vitro. Not only the electrophysiological characteristics of pacemaker and non-pacemaker neurons, but the cadmium-sensitivity of pacemaker neurons was observed. The nature of the discharge in the respiratory pacemaker neurons in mNRF was spontaneous, rhythmical and voltage-dependent burst behavior, generating an ectopic burst in response to a depolarizing or hyperpolarizing current. There were no significant differences in capacitance of membrane (C(m)), input resistance of membrane (R(m)) and leak inward current (I(leak)) between the pacemaker neurons and the non-pacemaker ones. Moreover, most pacemaker neurons in the mNRF were Cd(2+)-insensitive. In conclusion, these results support the idea that the mNRF is the site generating basic respiratory rhythm.

Role of 5-HT2A-receptors coupled with superoxide anion in the medial area of nucleus retrofacialis / 南方医科大学学报

<p><b>OBJECTIVE</b>To explore the effect of 5-HT2A-receptors coupled with superoxide anion (O2-) on respiratory regulation signal transductionin passageway in the medial area of nucleus retrofacialis (mNRF).</p><p><b>METHODS</b>mNRF island was prepared from medullary slices of neonatal SD rats according to Johnson's method and transferred separately into 24-well culture plates with reagents according to protocol, followed by incubation for 60 min at 37 degrees C in a humidified incubator with 5% CO2. Absorbance of 100 microl supernatant was measured by spectrophotometry at 550 nm and the effect of 5-HT and 2,5-dimethoxy-4-iodoamphetamine hydrochloride (DOI, agonist of 5-HT2A-receptors) on O2- generation in the mNRF was observed, along with the inhibition of this effect by ketanserin (antagonist of 5-HT2A-receptors) and alpha-lipoic acid (alpha-LA, a antioxidant).</p><p><b>RESULTS</b>5-HT concentration-response curve demonstrated that absorbance peak occurred at 1 micromol/L without further increment with higher concentration. DOI concentration-response curve showed the absorbance peak at 20 micromol/L without further increment. 5-HT and DOI significantly increased the absorbance with comparable effects. Ketanserin and alpha-LA significantly decreased the absorbance generated by 5-HT and DOI.</p><p><b>CONCLUSION</b>Activation of 5-HT2A receptors results in obvious O2- production in mNRF, suggesting that 5-HT2A receptors regulate respiratory function in association with O2-.</p>

Effects of sedation on respiratory mechanic dynamics and oxygen metabolism in patients with mechanical ventlilation / 中华急诊医学杂志

Objective To investigate the effect of sedation on respiratory mechanic dynamics, intrapulmonary shunt fraction,oxygen metabolism in patients with mechanical ventilation.Method Sixty patients with mechanical ventilation were divided randomly into control group and sedation group.Propofal was administered to patients,whose ramsay scores were kept atⅢorⅣlevels,in sedation group while the equal amount of normal saline was given in control group.Mixed venous blood and arterial blood samples were taken for blood gas analysis in both groups before and at 2 hours after administration.Heart rate,blood pressure,breathing rate and airway resistance all were recorded at the same time.Results There were no significant differences in oxygenation index,blood pressure,blood lactic acid,total lung static compliance and intrapulmonary shunt fraction between two groups before and after administration.Heart rate,respiratory rate,oxygen uptake and airway resistance of patients in sedation group were lower than those in control group,and partial pressure of oxygen in mixed venous blood of patients in sedation group were higher than those in control group.These differences were statistically significant.Conclusions Sedation can decrease oxygen uptake and airway resistance of patients with mechanical ventilation.However,no alteration in the oxygenation index,total lung static compliance and intrapulmonic shunt ratio can be observed.

Clinicopathologic features of usual interstitial pneumonia and its differential diagnosis from idiopathic nonspecific interstitial pneumonia / 中华病理学杂志

<p><b>OBJECTIVE</b>To investigate the clinicopathologic features of usual interstitial pneumonia (UIP) and its differential diagnosis from idiopathic nonspecific interstitial pneumonia (INSIP).</p><p><b>METHODS</b>The clinical and pathological features of 15 UIP and 11 cases of INSIP, having received open or video-assisted thoracoscopic lung biopsies and having follow-up information were reviewed.</p><p><b>RESULTS</b>UIP occurred more often in males over 50 years of age. Clinical findings included progressive shortness of breath, cough, sputum and crackles over both lung fields. High resolution computerized tomography (HRCT) showed patchy attenuation, especially over both lower lobes. Honeycombing was found in 8 cases. Histologically, UIP was characterized by scattered fibrotic foci, fibrosis (often associated with honeycombing) and pulmonary architectural destruction. It had a heterogeneous appearance, with alternating areas of normal lung, interstitial inflammation, fibrosis and honeycomb changes. The frequencies of fibroblastic foci, muscle sclerosis, honeycomb changes, diffuse fibrosis and pulmonary architectural destruction in UIP and INSIP were 100% and 27.3% (P<0.001), 80.0% and 36.4% (P<0.05), 86.7% and 27.3% (P<0.001), 100% and 54.5% (P<0.01) and 100% and 45.5% (P<0.05), respectively. The response rate to glucocorticoid was 26.7% and 72.7% (P<0.05) in UIP and INSIP respectively.</p><p><b>CONCLUSIONS</b>The distinction between UIP and INSIP is difficult if based on clinical examination alone. HRCT is helpful for differential diagnosis in some difficult cases. Definite diagnosis depends mainly on open lung biopsies. Key histologic features of UIP include heterogeneous appearance with interstitial inflammation, fibroblastic foci, scar formation and honeycomb changes.</p>