Temperature and state dependence of dynamic phrenic oscillations in the decerebrate juvenile rat

2007 ◽  
Vol 293 (6) ◽  
pp. R2323-R2335 ◽  
Author(s):  
Vitaliy Marchenko ◽  
Robert F. Rogers
Keyword(s):  
Low Frequency ◽  
State Dependence ◽  
Temperature Dependent ◽  
Time Frequency ◽  
High Frequency Oscillations ◽  
Effects Of Temperature ◽  
Fast Oscillations ◽  
Incomplete Ischemia

The aim of the present study was to determine characteristics of fast oscillations in the juvenile rat phrenic nerve (Ph) and to establish their temperature and state dependence. Two different age-matched decerebrate, baro- and chemodenervated rat preparations, in vivo and in situ arterially perfused models, were used to examine three systemic properties: 1) generation and dynamics of fast oscillations in Ph activity (both preparations), 2) responses to anoxia (both preparations), and 3) the effects of temperature on fast oscillations (in situ only). Both juvenile preparations generated power and coherence in two major bands analogous to adult medium- and high-frequency oscillations (HFO) at frequencies that increased with temperature but were lower than in adults. At < 28°C, however, Ph oscillations were confined primarily to one low-frequency band (20–45 Hz). During sustained anoxia, both preparations produced stereotypical state changes from eupnea to hyperpnea to transition bursting (a behavior present only in vivo during incomplete ischemia) to gasping. Thus the juvenile rat produces a sequential pattern of responses to anoxia that are intermediate forms between those produced by neonates and those produced by adults. Time-frequency analysis determined that fast oscillations demonstrated dynamics over the course of the inspiratory burst and a state dependence similar to that of adults in vivo in which hyperpnea (and transition) bursts are associated with increases in HFO, while gasping contains no HFO. Our results confirm that both the fast oscillations in Ph activity and the coherence between Ph pairs produced by the juvenile rat are profoundly state- and temperature-dependent.

scholarly journals Motoneuron firing patterns underlying fast oscillations in phrenic nerve discharge in the rat

2012 ◽  
Vol 108 (8) ◽  
pp. 2134-2143 ◽  
Author(s):  
Vitaliy Marchenko ◽  
Michael G. Z. Ghali ◽  
Robert F. Rogers
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Medium Frequency ◽  
Adult Rats ◽  
Time Frequency ◽  
High Frequency Oscillations ◽  
Novel Method ◽  
Frequency Coherence ◽  
Fast Oscillations ◽  
First Time

Fast oscillations are ubiquitous throughout the mammalian central nervous system and are especially prominent in respiratory motor outputs, including the phrenic nerves (PhNs). Some investigators have argued for an epiphenomenological basis for PhN high-frequency oscillations because phrenic motoneurons (PhMNs) firing at these same frequencies have never been recorded, although their existence has never been tested systematically. Experiments were performed on 18 paralyzed, unanesthetized, decerebrate adult rats in which whole PhN and individual PhMN activity were recorded. A novel method for evaluating unit-nerve time-frequency coherence was applied to PhMN and PhN recordings. PhMNs were classified according to their maximal firing rate as high, medium, and low frequency, corresponding to the analogous bands in PhN spectra. For the first time, we report the existence of PhMNs firing at rates corresponding to high-frequency oscillations during eupneic motor output. The majority of PhMNs fired only during inspiration, but a small subpopulation possessed tonic activity throughout all phases of respiration. Significant time-varying PhMN-PhN coherence was observed for all PhMN classes. High-frequency, early-recruited units had significantly more consistent onset times than low-frequency, early/middle-recruited and medium-frequency, middle/late-recruited PhMNs. High- and medium-frequency PhMNs had significantly more consistent offset times than low-frequency units. This suggests that startup and termination of PhMNs with higher firing rates are more precisely controlled, which may contribute to the greater PhMN-PhN coherence at the beginning and end of inspiration. Our findings provide evidence that near-synchronous discharge of PhMNs firing at high rates may underlie fast oscillations in PhN discharge.

Tissue-Light Interaction During Monitoring of Thermal Lesion Using Quantum Dot Mediated Fluorescence Thermometry

2011 ◽  
Author(s):  
Willard Hanson ◽  
Najma Abdollahzadeh ◽  
Bumsoo Han
Keyword(s):  
Diffusion Approximation ◽  
Treatment Options ◽  
Thermal Therapy ◽  
Temperature Dependent ◽  
Thermal Lesion ◽  
Tissue Phantom ◽  
Localized Heating ◽  
Light Interaction

Thermal therapy, destroying tumor in situ by localized heating, is emerging as one of the treatment options for benign and localized tumors. Despite many advantages of thermal therapy, its clinical application is still limited due to the lack of a reliable intraoperative monitoring technique of the thermal lesion. To address this challenge, an intraoperative thermometry technique has been proposed using the temperature-dependent fluorescence of quantum dots (QDs). Its feasibility is recently demonstrated by monitoring the spatiotemporal temperature during gold nanoshell-mediated heating. In the present study, the effects of tissue-light interaction on the QD-mediated thermometry were investigated both experimentally and theoretically so that the technique can be extended to in vivo applications. As for experimental investigation, the QD fluorescence through tissue phantom was characterized with varying the thickness of the phantom over a temperature range relevant to thermal therapy. The results showed that the QD fluorescence through tissue phantom was still linearly correlated to the local temperature, but the slope of the correlations decreased with the phantom thickness. As for theoretical investigation, the radiative transfer equation was reduced to the diffusion approximation, and the QD fluorescence through tissue phantom was predicted by numerically solving the diffusion approximation. The results confirmed that the diffusion approximation could describe the tissue-light interaction for the QD-mediated thermometry but further research is still required to improve the accuracy of the prediction.

Selective loss of high-frequency oscillations in phrenic and hypoglossal activity in the decerebrate rat during gasping

2006 ◽  
Vol 291 (5) ◽  
pp. R1414-R1429 ◽  
Author(s):  
Vitaliy Marchenko ◽  
Robert F. Rogers
Keyword(s):  
Power Distribution ◽  
High Frequency ◽  
Spectral Characteristics ◽  
Low Frequency ◽  
High Amplitude ◽  
Medial Branch ◽  
Adult Rats ◽  
Time Frequency ◽  
High Frequency Oscillations ◽  
Nerve Recordings

Respiratory motor outputs contain medium-(MFO) and high-frequency oscillations (HFO) that are much faster than the fundamental breathing rhythm. However, the associated changes in power spectral characteristics of the major respiratory outputs in unanesthetized animals during the transition from normal eupneic breathing to hypoxic gasping have not been well characterized. Experiments were performed on nine unanesthetized, chemo- and barodenervated, decerebrate adult rats, in which asphyxia elicited hyperpnea, followed by apnea and gasping. A gated fast Fourier transform (FFT) analysis and a novel time-frequency representation (TFR) analysis were developed and applied to whole phrenic and to medial branch hypoglossal nerve recordings. Our results revealed one MFO and one HFO peak in the phrenic output during eupnea, where HFO was prominent in the first two-thirds of the burst and MFO was prominent in the latter two-thirds of the burst. The hypoglossal activity contained broadband power distribution with several distinct peaks. During gasping, two high-amplitude MFO peaks were present in phrenic activity, and this state was characterized by a conspicuous loss in HFO power. Hypoglossal activity showed a significant reduction in power and a shift in its distribution toward lower frequencies during gasping. TFR analysis of phrenic activity revealed the increasing importance of an initial low-frequency “start-up” burst that grew in relative intensity as hypoxic conditions persisted. Significant changes in MFO and HFO rhythm generation during the transition from eupnea to gasping presumably reflect a reconfiguration of the respiratory network and/or alterations in signal processing by the circuitry associated with the two motor pools.

scholarly journals Beating Rate Variability of Isolated Mammal Sinoatrial Node Tissue: Insight Into Its Contribution to Heart Rate Variability

2021 ◽  
Vol 14 ◽  
Author(s):  
Ori Shemla ◽  
Kenta Tsutsui ◽  
Joachim A. Behar ◽  
Yael Yaniv
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Frequency Band ◽  
Sinoatrial Node ◽  
Low Frequency ◽  
Relative Increase ◽  
Test Mouse ◽  
Beating Rate

BackgroundBecause of the complexity of the interaction between the internal pacemaker mechanisms, cell interconnected signals, and interaction with other body systems, study of the role of individual systems must be performed under in vivo and in situ conditions. The in situ approach is valuable when exploring the mechanisms that govern the beating rate and rhythm of the sinoatrial node (SAN), the heart’s primary pacemaker. SAN beating rate changes on a beat-to-beat basis. However, to date, there are no standard methods and tools for beating rate variability (BRV) analysis from electrograms (EGMs) collected from different mammals, and there is no centralized public database with such recordings.MethodsWe used EGM recordings obtained from control SAN tissues of rabbits (n = 9) and mice (n = 30) and from mouse SAN tissues (n = 6) that were exposed to drug intervention. The data were harnessed to develop a beat detector to derive the beat-to-beat interval time series from EGM recordings. We adapted BRV measures from heart rate variability and reported their range for rabbit and mouse.ResultsThe beat detector algorithm performed with 99% accuracy, sensitivity, and positive predictive value on the test (mouse) and validation (rabbit and mouse) sets. Differences in the frequency band cutoff were found between BRV of SAN tissue vs. heart rate variability (HRV) of in vivo recordings. A significant reduction in power spectrum density existed in the high frequency band, and a relative increase was seen in the low and very low frequency bands. In isolated SAN, the larger animal had a slower beating rate but with lower BRV, which contrasted the phenomena reported for in vivo analysis. Thus, the non-linear inverse relationship between the average HR and HRV is not maintained under in situ conditions. The beat detector, BRV measures, and databases were contributed to the open-source PhysioZoo software (available at: https://physiozoo.com/).ConclusionOur approach will enable standardization and reproducibility of BRV analysis in mammals. Different trends were found between beating rate and BRV or HRV in isolated SAN tissue vs. recordings collected under in vivo conditions, respectively, implying a complex interaction between the SAN and the autonomic nervous system in determining HRV in vivo.

Effects of temperature on intracellular [Ca2+] in trout atrial myocytes

2002 ◽  
Vol 205 (23) ◽  
pp. 3641-3650 ◽  
Author(s):  
Holly A. Shiels ◽  
Matti Vornanen ◽  
Anthony P. Farrell
Keyword(s):  
Rainbow Trout ◽  
Negative Inotropic Effect ◽  
Frequency Change ◽  
Acute Effects ◽  
Temperature Dependent ◽  
Cold Temperatures ◽  
Channel Current ◽  
Effects Of Temperature ◽  
Increasing Temperature

SUMMARYAcute temperature change can be cardioplegic to mammals, yet certain ectotherms maintain their cardiac scope over a wide temperature range. To better understand the acute effects of temperature on the ectothermic heart,we investigated the stimulus-induced change in intracellular Ca2+concentration ([Ca2+]i; cytosolic Ca2+transient) in isolated rainbow trout myocytes at 7°C, 14°C and 21°C. Myocytes were voltage-clamped and loaded with Fura-2 to measure the L-type Ca2+ channel current (ICa) and[Ca2+]i during physiological action potential (AP)pulses at frequencies that correspond to trout heart rates in vivo at 7°C, 14°C and 21°C. Additionally, [Ca2+]iand ICa were examined with square (SQ) pulses at slow (0.2 Hz) and physiologically relevant contraction frequencies. The amplitude of[Ca2+]i decreased with increasing temperature for both SQ and AP pulses, which may contribute to the well-known negative inotropic effect of warm temperature on contractile strength in trout hearts. With SQ pulses, [Ca2+]i decreased from 474±53 nmol l-1 at 7°C to 198±21 nmol l-1 at 21°C,while the decrease in [Ca2+]i with AP pulses was from 234±49 nmol l-1 to 79±12 nmol l-1,respectively. Sarcolemmal Ca2+ influx was increased slightly at cold temperatures with AP pulses (charge transfer was 0.27±0.04 pC pF-1, 0.19±0.03 pC pF-1 and 0.13±0.03 pC pF-1 at 7°C, 14°C and 21°C, respectively). At all temperatures, cells were better able to maintain diastolic Ca2+levels at physiological frequencies with AP pulses compared with 500 ms SQ pulses. We suggest that temperature-dependent modulation of the AP is important for cellular Ca2+ regulation during temperature and frequency change in rainbow trout heart.

In Vivo/In Situ Detection of Nitric Oxide Using Low-Frequency EPR Spectroscopy

2003 ◽  
pp. 227-238
Author(s):  
Pei Tsai ◽  
Supatra Porasuphatana ◽  
Howard J. Halpern ◽  
Eugene D. Barth ◽  
Gerald M. Rosen
Keyword(s):  
Nitric Oxide ◽  
Epr Spectroscopy ◽  
Low Frequency ◽  
In Situ Detection

Time-frequency coherence analysis of phrenic and hypoglossal activity in the decerebrate rat during eupnea, hyperpnea, and gasping

2006 ◽  
Vol 291 (5) ◽  
pp. R1430-R1442 ◽  
Author(s):  
Vitaliy Marchenko ◽  
Robert F. Rogers
Keyword(s):  
Low Frequency ◽  
Adult Rats ◽  
Time Frequency ◽  
High Frequency Oscillations ◽  
Respiratory Network ◽  
Decerebrate Rat ◽  
State Changes ◽  
Nerve Recordings ◽  
Frequency Coherence ◽  
Respiratory Rhythms

Fast respiratory rhythms include medium- (MFO) and high-frequency oscillations (HFO), which are much faster than the fundamental breathing rhythm. According to previous studies, HFO is characterized by high coherence (Coh) in phrenic (Ph) nerve activity, thereby providing a means of distinguishing between these two types of oscillations. Changes in Coh between the Ph and hypoglossal (XII) nerves during the transition from normal eupnic breathing to gasping have not been characterized. Experiments were performed on nine unanesthetized, chemo- and barodenervated, decerebrate adult rats, in which sustained asphyxia elicited hyperpnea and gasping. A gated time-frequency Coh analysis was developed and applied to whole Ph and medial XII nerve recordings. The results showed dynamic Ph-Ph Coh during eupnea, including MFO and HFO. XII-XII Coh during eupnea was broadband and included four distinct peaks, with low-frequency Coh dominating the epochs preceding the onset of Ph activity. During gasping, only MFO-peaks were present in Ph-Ph Coh. Bilateral XII activity showed a significant reduction in Coh and a shift toward lower frequencies during gasping. In contrast, contralateral Ph-XII Coh progressively increased during state changes from eupnea to gasping, a tendency mirrored in the startup part of the Ph activity. These data suggest significant hypoxia/hypercapnia-induced alterations in synchronization between respiratory outputs during the transition from eupnea to gasping, reflecting a reconfiguration of the respiratory network and/or alterations in the circuitry associated with the motor pools, including dynamic coupling between outputs.

High-frequency oscillations of phrenic activity in eupnea and gasping of in situ rat: influence of temperature

2003 ◽  
Vol 285 (2) ◽  
pp. R404-R412 ◽  
Author(s):  
Walter M. St.-John ◽  
J. C. Leiter
Keyword(s):  
High Frequency ◽  
Power Spectra ◽  
Power Spectral Analysis ◽  
Peak Frequency ◽  
In Situ Preparation ◽  
High Frequency Oscillations ◽  
Power Spectral ◽  
Additional Support

We hypothesized that the in situ perfused preparation of the juvenile rat exhibits patterns of ventilatory activity comparable to eupnea and gasping in vivo. To evaluate this hypothesis, we examined high-frequency oscillations of activity of the phrenic nerve at 27–34°C. The peak frequency of these high-frequency oscillations was defined from power spectral analysis. In situ, recordings were obtained in hyperoxic normocapnia, during ventilatory cycles in which the peak of integrated phrenic activity was achieved late in the burst, as in eupnea in vivo. Recordings were also obtained in hypoxic hypercapnia, when the peak of integrated phrenic activity occurred in the first half of the burst, as in gasping in vivo. In situ, peak frequencies in the power spectra were significantly higher in gasping than during eupnea. Frequencies during eupnea and gasping were progressively elevated as the temperature of the in situ preparation was increased. The shift in peak frequencies between eupnea and gasping and the temperature sensitivity of frequencies in situ were the same as in vivo. Results provide additional support for the conclusion that the in situ preparation demonstrates distinctly different patterns of automatic ventilatory activity, comparable to eupnea and gasping in vivo.

Sign in / Sign up

Export Citation Format

Share Document