EFFECTS OF L-GLUTAMATE ON THE VENTILATORY RESPONSE TO HYPOXIA IN HYPOTHERMIC NEWBORN PIGLETS. † 2022
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Hypoxia
Phrenic nerve
Hypoxic ventilatory response
Bolus (digestion)
Respiratory Rate
The effects of microinjection of sodium glutamate and glycine into ventrolateral nucleus of tractus solitarius (VLNTS) on the discharges of phrenic nerve were observed on 40 anaesthetized, vagotomized, paralyzed and artificially ventilated rabbits. The results were as follows: Phrenic nerve discharges were increased, inspiratory duration prolonged, expiratory duration shortened and respiratory frequency not changed by microinjection of sodium glutamate into VLNTS. While by microinjection of glycine, phrenic nerve discharges were decreased, even abolished, inspiratory duration shortened, expiratory duration irregularly prolonged and respiratory frequency decreased. The above results show that VLNTS exert important effects on the genesis of respiratory rhythm.
Phrenic nerve
Respiratory center
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Protein kinase C (PKC) is a broadly expressed and critically important signalling protein with a wide range of functional roles, including central components of respiratory control. For example, systemic and targeted administration of PKC inhibitors within the nucleus of the solitary tract (nTS) markedly attenuates peak hypoxic ventilatory responses (HVR). Protein kinase C activation in phrenic motor nucleus has also been implicated in some forms of acute respiratory plasticity, such as phrenic long-term facilitation (pLTF), a persistent enhancement of phrenic motor output following acute intermittent hypoxia. To further examine the role of PKC within the nTS, the selective PKC antagonist bisindolylmaleimide I (BIM I) was microinjected in the area corresponding to the nTS via bilateral osmotic pumps in normoxic adult male Sprague-Dawley rats; control animals received bisindolylmaleimide V (BIM V, inactive analogue). In one series of experiments, hypoxic challenges (fractional inspired ) were conducted in unrestrained animals (n = 8 per group). No differences in baseline ventilation emerged; however, peak HVR was attenuated following BIM I (P < 0.01), primarily owing to reductions in respiratory frequency increases (P < 0.01). In a second series of experiments, integrated phrenic nerve activity was recorded in anaesthetized, vagotomized, paralysed and ventilated rats exposed to three 5 min hypoxic episodes separated by 5 min hyperoxia . During baseline conditions, no differences emerged in phrenic nerve output; however, phrenic nerve output measured during the initial hypoxic exposure was significantly attenuated in BIM I-treated rats (P < 0.01). In contrast, both groups of animals displayed significant pLTF (BIM I versus BIM V; n.s.). Thus, we conclude that PKC activation within the nTS is critically involved in the central response to acute hypoxia, but does not appear to play a role in either eliciting or maintaining pLTF.
Phrenic nerve
Hypoxic ventilatory response
Bisindolylmaleimide
Hypoxia
Intermittent hypoxia
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A novel approach utilizing current feedback for the cytoplasmic microinjection of biological cells is proposed. In order to realize the cytoplasmic microinjection on small adherent cells (diameter < 30 μm and thickness < 10 μm), an electrical model is built and analyzed according to the electrochemical properties of target cells. In this study, we have verified the effectiveness of the current measurement for monitoring the injection process and the study of ion channel activities for verifying the cell viability of the cells after the microinjection.
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Monitoring microinjection process of small and non-spherical living cells using electrical responses
Cell microinjection is widely applied in various biomedical researches. Notwithstanding the operation challenges on small adherent cells (diameter <; 30 μm), cell injection of small living cells are standard procedures in pathological studies. However, most conventional cell microinjection of small cells are operated manually and monitored visually under a microscope, which usually leads to the microinjection uncertainty and prolong the operation time. It is because the change of cell volume during microinjection is very subtle and difficult to be observed even though the fluorescent technique can be used. When the cell volume is getting smaller, the challenge of verification of microinjection will be increased dramatically. Therefore, we proposed a new monitoring approach to validate the cell microinjection rapidly and quantitatively for small and adherent cells.
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Phrenic nerve
Hypoxic ventilatory response
Hypoxia
Hypoglossal nerve
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Hypoxic ventilatory responses differ between rodent strains, suggesting a genetic contribution to interindividual variability. However, hypoxic ventilatory responses consist of multiple time-dependent mechanisms that can be observed in different respiratory motor outputs. We hypothesized that strain differences would exist in discrete time-dependent mechanisms of the hypoxic response and, furthermore, that there may be differences between hypoglossal and phrenic nerve responses to hypoxia. Hypoglossal and phrenic nerve responses were assessed during and after a 5-min hypoxic episode in anesthetized, vagotomized, and ventilated rats from four inbred strains: Brown Norway (BN), Fischer 344 (FS), Lewis (LW), and Piebald-viral-Glaxo (PVG). During baseline, burst frequency was higher in PVG than LW rats (P < 0.05), phrenic burst amplitude was higher in PVG vs. other strains (P < 0.05), and hypoglossal burst amplitude was higher in PVG and BN vs. FS and LW (P < 0.05). During hypoxia, burst frequency did not change in BN or LW rats, but it increased in PVG and FS rats. The phrenic amplitude response was smallest in PVG vs. other strains (P < 0.05), and the hypoglossal response was similar among strains. Short-term potentiation posthypoxia was slowest in FS and fastest in LW rats (P < 0.05). Posthypoxia frequency decline was absent in PVG, but it was observed in all other strains. Augmented breaths were observed during hypoxia in FS rats only. Thus genetic differences exist in the time domains of the hypoxic response, and these are differentially expressed in hypoglossal and phrenic nerves. Furthermore, genetic diversity observed in hypoxic ventilatory responses in unanesthetized rats may arise from multiple neural mechanisms.
Phrenic nerve
Hypoxic ventilatory response
Hypoxia
Hypoglossal nerve
Intermittent hypoxia
Inbred strain
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INTRODUCTION This protocol describes a method for plating cells for microinjection onto etched coverslips. The coverslips for microinjection must be marked so that microinjected cells can be identified at time points after injection. A procedure for etching coverslips is given below; alternatively, pre-etched coverslips can be purchased at slightly higher cost.
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INTRODUCTION Direct-pressure microinjection with a micropipette is an essential tool for introducing a variety of impermeant substances into the cytoplasm or nucleus of plant and animal cells. Microinjection remains the most direct method to gain insight into the function and dynamics of intracellular components, to produce transgenic animals, or to overcome male infertility. This article describes the basic components of a microinjection system.
Pipette
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