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PubMed1993

Influence of respiration on heart rate and blood pressure fluctuations.

The dynamics of the respiratory and cardiovascular systems were studied by continuously slowing respiration from 0.46 to 0.05 Hz. The time-frequency distribution and global spectral analysis were used to assess the R-R interval (R-R) and the systolic and diastolic blood pressure fluctuations in 16 healthy subjects. During rest, the nonrespiratory-to-respiratory frequency ratios were not affected by occasional slow breathing, whereas the low- (0.01-0.15 Hz) to high- (0.15-0.3 Hz) frequency indexes for blood pressure were increased (P < 0.05). The respiratory fluctuations in R-R and the systolic and diastolic pressures were paced over the 0.46- to 0.05-Hz range. As respiration slowed to 0.07-0.09 Hz, the frequency content of the respiration and cardiovascular variables increased sharply and nonlinearly to a maximum that exceeded values at higher frequencies (P < 0.001). The nonrespiratory frequency content remained stable in the 0.01- to 0.05-Hz range and did not significantly differ from that at rest. In contrast, the nonstable 0.05- to 0.1-Hz component was suppressed. A slow 0.012- to 0.017-Hz rhythm modulated respiration and hemodynamic fluctuations at both respiratory and nonrespiratory frequencies. The study indicated that respiration input should be considered in the interpretation of global spectra. Furthermore the time-frequency distributions demonstrated that a close nonlinear coupling exists between the respiratory and cardiovascular systems.

Adult↗

PubMed1993

An investigation of the coupling between respiration, mastication, and swallowing in the awake rabbit.

1. The interrelationships between respiration, mastication, and swallowing were studied in awake rabbits previously prepared for the chronic recording of jaw movements and the electromyographic activity of jaw and throat muscles. These signals were recorded before, during, and after the mastication of rabbit chow, together with respiratory movements. 2. The onset of activity in the thyrohyoid muscle was used as a marker for swallowing. Measurements were made of cycle duration, and the phase relationship between the masticatory and respiratory rhythms was calculated. Deviations in masticatory and respiratory movements during swallowing were detected; the phases of the masticatory and respiratory cycles in which the deviations occurred were determined, and the intervals between the deviations and the swallowing marker were calculated. 3. Two characteristic swallowing patterns were observed that were called Interposed and Terminal swallows. Interposed swallows occurred within a masticatory sequence, while Terminal swallows ended the sequence. 4. In most rabbits, respiratory rate slowed during mastication. This brought the average frequency of the two movements closer together, and there was a weak but significant correlation between the masticatory and respiratory rates. However, respiration and mastication were not linked on a cycle-by-cycle basis, and the change in respiratory rate was found to be unrelated to masticatory rate. Further, there was no tendency for the masticatory and respiratory rhythms to adopt any particular phase relationship as swallowing was approached. Some weak and transient phase coupling of the two systems occurred after swallowing. 5. During swallowing, respiration was most often inhibited soon after the start of the inspiratory phase. Swallows within a masticatory sequence occurred most frequently during the early opening phase of the masticatory cycle, and swallows after the end of a sequence occurred with the jaw in the resting position. There was a strong tendency for the durations of the masticatory and respiratory cycles containing deviations to be longer than preceding control cycles, and the effect on respiration lasted several cycles. 6. For both Interposed and Terminal swallows, a tight temporal relationship was observed between deviations in respiration and the swallowing marker: most deviations tended to occur before swallowing. In contrast, the time of deviations in mastication relative to the swallowing marker depended on swallow type and was more variable. Finally, there was no link between the start of the pauses in the two rhythms. 7. We conclude that respiratory and masticatory processes are not strongly coupled.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed2003

Evaluation of baroreflex sensitivity by the sequence method using blood pressure oscillations and R-R interval changes during deep respiration.

BACKGROUND: Baroreflex sensitivity assessments have been considered to be important to evaluate cardiac autonomic neuropathy. The phenylephrine method, Valsalva maneuver or sequence method at rest caused several problems. We evaluated the usefulness of the sequence method during deep respiration. METHOD: Baroreflex sensitivity was evaluated in 20 normal volunteers and 50 patients with Parkinson's disease. R-R intervals and systolic blood pressures were obtained by electrocardiogram and tonometry using a continuous blood pressure monitoring system. The sequence method is an evaluation of baroreflex sensitivity using sequences of 3 or more consecutive beats for 4 min. Baroreflex sensitivity was also assessed by the Valsalva maneuver at 5 beats before the peak systolic blood pressure of phase IV. The slope of the linear interrelationship between systolic blood pressure and the following R-R interval, i.e. baroreflex sensitivity (ms/mm Hg), was calculated with a correlation coefficient greater than 0.8. RESULT: The mean value of baroreflex sensitivity obtained by the Valsalva maneuver was 7.91 in normal volunteers and 5.35 in patients with Parkinson's disease; the one obtained by the sequence method at rest was 9.10 in normal volunteers and 8.42 in patients with Parkinson's disease, and the one obtained by the sequence method during deep respiration was 10.23 in normal volunteers and 6.73 in patients with Parkinson's disease. In some cases with Parkinson's disease, baroreflex sensitivities could not be found, whereas in all patients with Parkinson's disease, the sequence method during deep respiration could be used for evaluations. Significant correlations were found among the baroreflex sensitivities obtained by the Valsalva maneuver, and the sequence method at rest or during deep respiration in normal volunteers and patients with Parkinson's disease. CONCLUSIONS: The baroreflex sensitivity obtained by the sequence method during deep respiration could be investigated noninvasively in all cases with PD, being thus a useful method for clinical evaluation of baroreflex sensitivity.

Aged↗

PubMed2006

Cytochrome c oxidase maintains mitochondrial respiration during partial inhibition by nitric oxide.

Nitric oxide (NO), generated endogenously in NO-synthase-transfected cells, increases the reduction of mitochondrial cytochrome c oxidase (CcO) at O2 concentrations ([O2]) above those at which it inhibits cell respiration. Thus, in cells respiring to anoxia, the addition of 2.5 microM L-arginine at 70 microM O2 resulted in reduction of CcO and inhibition of respiration at [O2] of 64.0+/-0.8 and 24.8+/-0.8 microM, respectively. This separation of the two effects of NO is related to electron turnover of the enzyme, because the addition of electron donors resulted in inhibition of respiration at progressively higher [O2], and to their eventual convergence. Our results indicate that partial inhibition of CcO by NO leads to an accumulation of reduced cytochrome c and, consequently, to an increase in electron flux through the enzyme population not inhibited by NO. Thus, respiration is maintained without compromising the bioenergetic status of the cell. We suggest that this is a physiological mechanism regulated by the flux of electrons in the mitochondria and by the changing ratio of O2:NO, either during hypoxia or, as a consequence of increases in NO, as a result of cell stress.

Arginine↗

PubMed1996

Oxygen-dependent reversible inhibition of mitochondrial respiration by nitric oxide.

Effects of nitric oxide (NO) and NO generating agents, on the electron transport system of mitochondria were examined in a study of the mechanism and physiological importance of NO in energy metabolism. In the presence of various substrates, uncoupled respiration was inhibited by NO in manner which was both dose- and oxygen tension-dependent. Simultaneously measuring changes in cytochrome absorption spectra and respiration showed that the site of action of NO is cytochrome oxidase. Similar inhibition was also brought about by 1-hydroxy-2-oxo-3,3-bis(2-aminoethyl)-1-triazene (NOC 18), an NO donor. Electron paramagnetic resonance (EPR) analysis revealed that inhibition of uncoupled respiration occurred only during the presence of NO in the reaction mixture. The inhibitory effect of NO was increased significantly by lowering the concentration of mitochondrial protein. No appreciable inhibition of respiration was observed in the presence of 3-morpholinosydnonimine (SIN-1), a peroxynitrite anion (ONOO-) generating reagent, but inhibition did occur in the presence of superoxide dismutase (SOD). These results indicate that NO reversibly interacts with mitochondria at complex IV thereby inhibiting respiration particularly under physiologically low oxygen tension and that de novo generated ONOO may have no significant effect under the present experimental conditions.

Animals↗

PubMedDate not supplied

Sublethal exposure to UV radiation affects respiration rates of the freshwater cladoceran Daphnia catawba.

We examined the effects of UV radiation (UVR) on metabolic rates of the freshwater cladoceran Daphnia catawba. We exposed D. catawba to UVB for 12 h in a lamp phototron at levels of 2.08 and 4.16 kJ m(-2) both with and without concomitant exposure to UVA and visible photorepair radiation (PRR). We also included a group that received PRR only and a dark control group. Respiration rates were measured for 6 h following exposure. Respiration rates increased by 31.8% relative to the dark control at the lowest level of UVB stress (2.08 kJ m(-2) UVB with PRR), whereas respiration was inhibited by 70.3% at the highest stress level (4.16 kJ m(-2) UVB without PRR). Survival rates in the group that received PRR only and the group exposed to 2.08 kJ m(-2) and PRR were not significantly different from that in the control group; however, the survival rate was reduced for all other UVR exposures. We hypothesize that enhanced respiration rates reflect energetic costs related to repair of cellular components damaged by sublethal levels of UVR. Increases in respiration rate of the magnitude we found in our experiment could significantly reduce energetic reserves available for growth and reproduction, especially in cases where these costs are incurred repeatedly during a series of days with high levels of UVR.

Animals↗

PubMed2000

Morphine inhibits resting respiration, but it attenuates reflexive respiratory suppression in anesthetized cat through kappa-receptor.

Noxious stimulation of thin-fiber muscular afferents induces a reflexive respiratory suppression that we call "poststimulus respiratory suppression." In anesthetized, vagotomized, paralyzed, and artificially ventilated cats, morphine depressed the level of resting respiration (inhibitory effect on resting respiration) and attenuated the magnitude of the poststimulus respiratory suppression (excitatory effect on the reflexively modified respiration). These two kinds of morphine effects were antagonized by naloxone, suggesting the participation of opioid receptors. To clarify the opioid receptor subtypes responsible for these effects of morphine, three type-selective opioid antagonists-naltrindole (delta antagonist), gamma-funaltrexamine (mu antagonist), and Mr2266 (kappa antagonist)-were tested. The morphine-induced depression in the resting respiration was antagonized by pretreatment with the kappa antagonist, not with the mu or delta antagonist. Furthermore, the morphine-induced attenuation in the magnitude of the poststimulus suppression was also blocked by the kappa antagonist, but not by the mu or delta antagonist. In conclusion, (1) morphine inhibits resting respiration, but it attenuates the magnitude of the poststimulus respiratory suppression; (2) both these morphine effects are mediated by kappa opioid receptors. The possibility that the kappa(3) receptor, one of the kappa receptors subtypes, mediates the two kinds of morphine effects has been discussed.

Analgesics, Opioid↗

PubMed2006

[Effects of drought stress on cyanide-resistant respiration and metabolism of reactive oxygen in wheat seedling].

The changes in cyanide-resistant respiration and metabolism of active oxygen species in drought-sensitive and drought-resistant wheat seedlings under water stress were studied. In general, drought stress decreased the level of cyanide-resistant respiration and AOX1 mRNA content in wheat seedling leaves. But the drought-resistant cultivars, which had much higher level of cyanide-resistant respiration and AOX1 mRNA content than the drought-sensitive ones, presented an ability to adapt to mild drought stress. Under drought stress, the drought-sensitive wheat seedling leaves had higher O(-.)(2) and H(2)O(2) contents, but lower SOD, POX and CAT activities than drought-resistant cultivars. We guessed that severe drought stress could break down the balance between active oxygen species and cyanide-resistant respiration. However, cyanide-resistant respiration still could participate in the drought-resistance by lowering the level of active oxygen species besides by other mechanism.

Blotting, Northern↗

PubMed1991

Respiration effect on standing balance.

An attempt was made to determine the effect of respiration on standing balance. Ten able-bodied subjects were asked to stand upright on a force platform and were asked to hold their breath after inspiration and after expiration, and to breathe regularly, 4, 6, and 8 respirations per 20 seconds. Sway was measured over 20-second periods with eyes open and eyes closed. The results show that both respiration and eye condition affect the sway distance of the center of pressure on body balance. The sway distance in holding breath after inspiration is significantly greater than in holding breath after expiration, and increasing the respiration rate produces a greater postural sway. Also, the grade of visual compensation for body balance is higher in the regular respiration condition than in breath holding. These findings are applicable for ergonomics, sports, and clinical situations.

Adult↗

PubMed1988

Effects of industrial respirators on respiratory timing and psychophysiologic load sensitivity.

Loads imposed by industrial respirators include inspiratory flow resistance and dead space. Eleven normal subjects were studied at five levels of treadmill exercise (from resting to peak) with and without a respirator surrogate load (single air-purifying cartridge plus 300 ml dead space). Analysis of variance with linear contrasts was used to separate interpersonal from respirator effects. The respiratory pattern was significantly affected, prolonging inspiration, decreasing peak inspiratory flow rates, and increasing tidal volume. Sensitivity to respiratory loads was measured by the magnitude estimation method; the respirator load, but not exercise, decreased load sensitivity. Interpersonal differences in load sensitivity were relatively large. This study suggests that tolerance to respiratory loads similar to those of respirators may be significantly affected by respiratory timing and load sensitivity adaptation. Poor tolerance by some workers might be related to abnormal psychophysiologic load sensitivity.

Adaptation, Physiological↗

PubMed1979

[Acute hypoxia and internal intensive medicine. III. Differentiated respiration].

In the third information concerning the topic "acute hypoxia and internal intensive medicine" the fundamentals of differentiated respiration are described. Current generators with constant and variable flow are best suited to remove the combined disturbances of the inhomogeneous lung or their results. In the Medivent-series a choice of types of respiratory apparatuses is at disposal by means of which a large part of respiratory disturbances may be commanded. A comprehensive possibility of the modification of the characteristics of respiration by an adjustibility of the sizes of respiration which are independent upon another is to be demanded. The PEEP is a valuable enlargement of the characteristics of respiration. Its effects are to be controlled in reaction to the circulation. In the centre of the information is the immediate practical approach in indication, choice of the parameters, adaptation of the patient to respiration and withdrawal.

Acute Disease↗

PubMed1979

[An experimental study on the regional blood flow in the cervical spinal cord --the influence of respiration (author's transl)].

The responses of cervical spinal cord blood flow (C-SCBF) to alteration in respiration were examined in gallamine immobilized and respiration controlled cats. Alveolar PCO2 was continuously monitored with an infrared CO2 analyzer. Mean arterial blood pressure (BP) was measured through femoral canula, which also allowed collection of arterial samples for blood gas analysis. C-SCBF was measured using thermoelectrical element which placed on the dorsal surface of the C6 segment. Simultaneously, changes in blood flow of cerebral cortex, L4 segment of spinal cord, heart and skeletal muscles, skin, kidney and spleen were also measured and compared with that of C-SCBF. Cerebrospinal fluid pressure (CSFP) was also measured on C5 segment. Changes in the arterial or alveolar PCO2 increased about 20--30 mmHg following respiration arrest or 10% CO2 inhalation, and decreased about 20 mmHg following hyperventilation during 2 minutes, respectively. Respiratory arrest or 10% CO2 inhalation induced an increase in C-SCBF, and a rise in BP and CSFP. Hyperventilation induced a decrease in C-SCBF, a fall in BP and a rise in CSFP. Effect of the respiration on blood flow of cerebral cortex, L4 segment of spinal cord or heart muscle was similar to the effect on C-SCBF in direction, but that of skin, skeletal muscle, kidney or spleen was conversely. C-SCBF increase by respiratory arrest or 10% CO2 inhalation was incompletely suppressed by pretreatment of propranolol 7 mg/kg i.v., C-SCBF decrease by hyperventilation was also incompletely suppressed by pretreatment of phentolamine 5 mg/kg i.v.. Furthermore, these C-SCBF changes were almost completely suppressed by pretreatment of phentolamine 5 mg/kg, propranolol 7 mg/kg and acetazolamide 250 mg/kg i.v. These results suggest that response of C-SCBF to alteration in respiration is chiefly induced by changes in PCO2, that CO2 acts directly on vascular smooth muscle and also on alpha and beta adrenergic receptors in the cervical spinal cord, and that CO2 has a similar action on the C-SCBF as on the blood flow of cerebral cortex, lumbar spinal cord and heart muscle.

Animals↗

PubMed1983

[Role of the opioidergic system in regulating respiration].

Experiments on anesthetized rats were made to study the effects of naloxone, bradykinin and thyroliberin on respiration. Naloxone, bradykinin and thyroliberin were found to eliminate respiratory depression induced by morphine and an enkephalin analog. Bradykinin primarily increased the amplitude, while thyroliberin the rate of respiration. Naloxone increased both the rate and amplitude of respiration. It is assumed that the noted difference in the action of naloxone, bradykinin and thyroliberin on respiration is linked with their effects on different types of opiate receptors involved in respiration control.

Animals↗

PubMed1984

Interrelationship of some electrocardiogram amplitudes, time intervals and respiration in the horse.

The relationship of the scalar and vector magnitudes of the QRS waveform to RR, PR and respiration was examined in 10 horses in regular rhythm using an orthogonal lead system. There were no significant changes in the durations of RR and PR with respiration. The amplitudes of the scalar variables XR and YR were directly related and that of XQ (or XS) and ZR were inversely related to PR in this group of horses. The peak spatial vector magnitude and its H-plane angle were directly related to PR and inversely related to RR. The effect of inspiration on the QRS was a decrease in YR and ZR, an increase in YS and peak spatial vector magnitude and a reduction in its angle of elevation. Examined over the 10 horses these changes were only small (1.8 to 3.8 per cent) and considered to be not significant clinically. The possible mechanisms of the relationship to PR and RR and the effect of respiration on the QRS waveform are discussed. The results suggest the possibility of a vagal effect on intraventricular conduction. The effect of respiration was shown to be independent of this effect and it might be due to changes in lung electrical conductivity during respiration.

Animals↗

PubMed1982

Behaviour-dependent changes of visually evoked potentials and their correlation to the respiration rate in freely moving rats.

The variability of visually evoked potentials (VEP) during spontaneous changes of behavioural activity was investigated in freely moving rats with electrodes in the visual and frontal cortex, olfactory bulb and other brain structures. Averaged VEP were recorded and compared during periods of characteristic behaviour types like drowsiness, relaxed wakefulness, attentiveness, grooming and exploratory behaviour. These behavioural patterns, which are clearly distinguishable by observation, were characterized by a certain degree of visually evoked afterdischarges, recorded movements, EEG-patterns and mean respiration rate. The evaluation of early components of the VEP from single recorded samples and of the correspondent momentary respiration rate (respiration intervals) revealed strongly negative correlations. In general, the increasing behavioural activity is characterized by a decrease in the amplitudes of VEP-components, inversely correlated to the log of momentary respiration rate. During drowsiness and enhanced attentiveness, certain components are increased. During strong movements and distraction of attention (e.g. intensive scratching and licking) the VEP-components were decreased stronger. The negative complex around 62 ms increased during certain forms of behavioural activation and locomotion. The VEP-component N31, the respiration rate, and the quotient N31: N61 were found suitable parameters to characterize certain types of behaviour in comparison to relaxed wakefulness.

Animals↗

PubMed1994

[Respiration-dependence of cutaneous laser Doppler flow motion].

The aim of this study was to show and to quantify the breath-dependency of cutaneous fluxmotion in the volar proximal forearm using a new computer-aided system. A meanflux-related index (MI) representing the intensity of the influence of respiration on fluxmotion was calculated. There was a good correlation between MI and the rate of respiration under spontaneous breathing: the lower the rate of respiration, the higher the value of MI. Prescribing a constant breathing rhythm amplifies this frequency-dependent effect. According to occurrence of low rates of respiration (< 12/min) also under physiological conditions the respiration should be simultaneously recorded while assessing fluxmotion.

Adolescent↗

PubMed1996

[Cortical and thalamic regulating mechanisms of the pulse neuron activity of oblongata medulla respiration center of the rats in normal condition and during hypoxia].

In normoxia, the orbitofrontal cortex and thalamic mediodorsal nucleus (MDN) basically inhibit the pulse activity of bulbar respiratory neurons and respiration in general. During initial hypoxia (4,000-5,000 m) a slight reduction of PO2 in the inspired air increases excitability of all the brain structures including those under study. However, strengthening of the orbitofrontal cortex and MDN inhibitory effect was leveled down by activizing brain structures, and the direct exciting effect of reduced PO2 on peripheral and central chemoreceptors. As a result, respiration became hurried in that period. Still, this inhibitory effect appears to play a positive role too. Unobstructed enhancement of activizing neural and humoral regulators of respiration might have led to intense hyperventilation fraught with an opposite action, i.e., inhibition, if not arrest of respiration consequent to reduced PO2 blood level, etc. Under acute hypoxia (7.5,000-8,000 m), oxygen deficit brings about inhibition, of all the brain structures including the orbitofrontal cortex and MDN. Moderation of their inhibitory effect in this period also plays an important role as it stimulates liberation of activizing systems and a relative increase in the ventilatory function of respiration.

Animals↗

PubMed2003

Using respirators and goggles to control exposure to air pollutants in an anatomy laboratory.

BACKGROUND: Engineering or administrative methods are often insufficient or impractical to control exposure to chemicals in anatomy laboratories. This study explored the feasibility of wearing one or a combination of respirators and goggles used as personal protective equipment (PPE) to control exposure in one such laboratory. METHODS: A group of 28 subjects were briefly trained in wearing PPE, fit-tested, and asked to complete a questionnaire regarding their subjective reaction after wearing the assigned PPE ensemble while working in the laboratory. The subjects' exposure to formaldehyde was also measured and generally exceeded the recommended limits. RESULTS: When a full-face respirator or the combination of a half-mask respirator and goggles was worn, a majority of subjects reported no odor problem and no irritation to eyes or upper respiratory system. Subjects accepted the PPE to certain degrees, but those using respirators encountered difficulties communicating with others. CONCLUSIONS: The combination of a half-mask respirator and goggles was the most feasible ensemble to control exposure to air pollutants in an anatomy laboratory.

Adult↗