1
|
Abstract
Sensory nerves innervating the lung and airways play an important role in regulating various cardiopulmonary functions and maintaining homeostasis under both healthy and disease conditions. Their activities conducted by both vagal and sympathetic afferents are also responsible for eliciting important defense reflexes that protect the lung and body from potential health-hazardous effects of airborne particulates and chemical irritants. This article reviews the morphology, transduction properties, reflex functions, and respiratory sensations of these receptors, focusing primarily on recent findings derived from using new technologies such as neural immunochemistry, isolated airway-nerve preparation, cultured airway neurons, patch-clamp electrophysiology, transgenic mice, and other cellular and molecular approaches. Studies of the signal transduction of mechanosensitive afferents have revealed a new concept of sensory unit and cellular mechanism of activation, and identified additional types of sensory receptors in the lung. Chemosensitive properties of these lung afferents are further characterized by the expression of specific ligand-gated ion channels on nerve terminals, ganglion origin, and responses to the action of various inflammatory cells, mediators, and cytokines during acute and chronic airway inflammation and injuries. Increasing interest and extensive investigations have been focused on uncovering the mechanisms underlying hypersensitivity of these airway afferents, and their role in the manifestation of various symptoms under pathophysiological conditions. Several important and challenging questions regarding these sensory nerves are discussed. Searching for these answers will be a critical step in developing the translational research and effective treatments of airway diseases.
Collapse
Affiliation(s)
- Lu-Yuan Lee
- Department of Physiology, University of Kentucky, Lexington, Kentucky
| | | |
Collapse
|
2
|
Abstract
Many articles in this section of Comprehensive Physiology are concerned with the development and function of a central pattern generator (CPG) for the control of breathing in vertebrate animals. The action of the respiratory CPG is extensively modified by cortical and other descending influences as well as by feedback from peripheral sensory systems. The central nervous system also incorporates other CPGs, which orchestrate a wide variety of discrete and repetitive, voluntary and involuntary movements. The coordination of breathing with these other activities requires interaction and coordination between the respiratory CPG and those governing the nonrespiratory activities. Most of these interactions are complex and poorly understood. They seem to involve both conventional synaptic crosstalk between groups of neurons and fluid identity of neurons as belonging to one CPG or another: neurons that normally participate in breathing may be temporarily borrowed or hijacked by a competing or interrupting activity. This review explores the control of breathing as it is influenced by many activities that are generally considered to be nonrespiratory. The mechanistic detail varies greatly among topics, reflecting the wide variety of pertinent experiments.
Collapse
Affiliation(s)
- Donald Bartlett
- Department of Physiology & Neurobiology, Dartmouth Medical School, Lebanon, New Hampshire, USA.
| | | |
Collapse
|
3
|
Morélot-Panzini C, Corvol JC, Demoule A, Raux M, Fiamma MN, Willer JC, Similowski T. Intravenous adenosine activates diffuse nociceptive inhibitory controls in humans. J Appl Physiol (1985) 2013; 115:697-703. [DOI: 10.1152/japplphysiol.00027.2013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Experimentally induced pain can be attenuated by concomitant heterotopic nociceptive stimuli (counterirritation). Animal data indicate that this stems from supraspinal “diffuse noxious inhibitory controls” (DNICs) triggered by C and Aδ fibers. In humans, only noxious stimuli induce counterirritation. This points at C fibers, but the effects of pharmacologically stimulating C fibers have not been studied. Intravenous adenosine activates pulmonary C fibers and induces dyspnea. This study tests the hypothesis that putative activation of pulmonary C fibers by adenosine would trigger DNICs in humans and induce counterirritation. Twelve healthy volunteers were included (with valid results available in 9) and studied according to a double-blind, randomized, cross-over design (intravenous adenosine, 140 μg·kg−1·min−1, during 5 min vs. placebo). We measured ventilatory variables and end-tidal CO2 tension, dyspnea intensity by visual analog scale, and the intensity of putative chest pain. The primary outcome was the amplitude of the RIII component of the nociceptive flexor reflex recorded by biceps femoris electromyogram in response to painful electrical sural nerve stimulation (RIII), taken as a substitute for pain perception. Placebo did not induce any significant effect. Adenosine induced dyspnea, hyperpnea, tachycardia, and significant RIII inhibition (24 ± 8% at the 4th min, P < 0.0001). The temporal dynamics of adenosine-induced dyspnea and RIII inhibition differed (immediate onset followed by a slow decrease for dyspnea, slower onset for RIII inhibition). Intravenous adenosine in normal humans induces counterirritation, fueling the notion that C-fiber stimulation trigger DNICs in humans. The temporal dissociation between adenosine-induced dyspnea and RIII inhibition suggests that C fibers other than pulmonary ones might be involved.
Collapse
Affiliation(s)
- Capucine Morélot-Panzini
- Assistance Publique - Hôpitaux de Paris, Groupe Hospitalier Pitié Salpêtrière Charles Foix, Service de Pneumologie et Réanimation Médicale, Paris, France
- Université Paris 6, ER10UPMC, Paris, France
| | - Jean-Christophe Corvol
- Assistance Publique - Hôpitaux de Paris, Groupe Hospitalier Pitié Salpêtrière Charles Foix, Département de Neurologie, Département de Pharmacologie, INSERM CIC-9503, Paris, France
- INSERM UMRS975 UPMC, CNRS UMR 7225, CR ICM, Pitié-Salpêtrière, Paris, France
| | - Alexandre Demoule
- Assistance Publique - Hôpitaux de Paris, Groupe Hospitalier Pitié Salpêtrière Charles Foix, Service de Pneumologie et Réanimation Médicale, Paris, France
- Université Paris 6, ER10UPMC, Paris, France
| | - Mathieu Raux
- Université Paris 6, ER10UPMC, Paris, France
- Assistance Publique - Hôpitaux de Paris, Groupe Hospitalier Pitié Salpêtrière Charles Foix, Département d'Anesthésie et Réanimation, Paris, France; and
| | - Marie-Noëlle Fiamma
- Assistance Publique - Hôpitaux de Paris, Groupe Hospitalier Pitié Salpêtrière Charles Foix, Service de Pneumologie et Réanimation Médicale, Paris, France
- Université Paris 6, ER10UPMC, Paris, France
| | - Jean-Claude Willer
- Assistance Publique - Hôpitaux de Paris, Groupe Hospitalier Pitié Salpêtrière Charles Foix, Département d'Anesthésie et Réanimation, Paris, France; and
- Assistance Publique - Hôpitaux de Paris, Groupe Hospitalier Pitié Salpêtrière Charles Foix, Département de Neurophysiologie Clinique, Paris, France
| | - Thomas Similowski
- Assistance Publique - Hôpitaux de Paris, Groupe Hospitalier Pitié Salpêtrière Charles Foix, Service de Pneumologie et Réanimation Médicale, Paris, France
- Université Paris 6, ER10UPMC, Paris, France
| |
Collapse
|
4
|
Effect of sublingual nitrate on respiratory reflexes arising from stimulation of juxta-pulmonary capillary (J) receptors by i.v. lobeline and short duration exercise. Respir Physiol Neurobiol 2012; 181:259-66. [DOI: 10.1016/j.resp.2012.03.020] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Revised: 03/27/2012] [Accepted: 03/29/2012] [Indexed: 11/20/2022]
|
5
|
Kang KS, Yahashi S, Matsuda K. Central and peripheral effects of ghrelin on energy balance, food intake and lipid metabolism in teleost fish. Peptides 2011; 32:2242-7. [PMID: 21601604 DOI: 10.1016/j.peptides.2011.05.006] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2011] [Revised: 04/24/2011] [Accepted: 05/05/2011] [Indexed: 11/23/2022]
Abstract
Ghrelin was first identified and characterized from rat stomach as an endogenous ligand for the growth hormone secretagogue receptor. Ghrelin and its receptor system are present not only in peripheral tissues such as stomach and intestine, but also in the central nervous system of mammals. Interestingly, administration of ghrelin induces an orexigenic effect and also modifies locomotor activity, suggesting its involvement in feeding control and the regulation of energy balance, in addition to the regulation of growth hormone release. Information about ghrelin in non-mammals, such as teleost fish, has also been increasing, and important data have been obtained. An understanding of the evolutionary background of the energy regulation system and the central and peripheral roles of ghrelin in teleost fish could provide indications as to their roles in mammals, particularly humans. In this review, we overview the central and peripheral effects of ghrelin on energy balance, locomotor activity, and lipid metabolism in teleost fish.
Collapse
Affiliation(s)
- Ki Sung Kang
- Laboratory of Regulatory Biology, Graduate School of Science and Engineering, University of Toyama, 3190-Gofuku, Toyama 930-8555, Japan
| | | | | |
Collapse
|
6
|
Kang KS, Yahashi S, Matsuda K. The effects of ghrelin on energy balance and psychomotor activity in a goldfish model: an overview. INTERNATIONAL JOURNAL OF PEPTIDES 2011; 2011:171034. [PMID: 21760819 PMCID: PMC3133451 DOI: 10.1155/2011/171034] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/02/2011] [Accepted: 03/22/2011] [Indexed: 12/14/2022]
Abstract
The goldfish (Carassius auratus) has a number of merits as a laboratory animal, and we have extensively identified the mechanisms by which ghrelin regulates food intake in this species. For the first time, we have purified and characterized 11 molecular variants of ghrelin that are present in goldfish intestine and shown that 17-residue ghrelin, the predominant form with n-octanoyl modification, is biologically active and implicated in the regulation of food intake as an endogenous orexigenic factor. Ghrelin and its receptor system are present not only in peripheral tissues such as stomach and intestine, but also in the central nervous system. Recent studies have also revealed that a number of neuropeptides are widely distributed in the brain in key areas of emotional regulation, and their role as modulators of behavioral states is being increasingly recognized. Interestingly, administration of ghrelin induces an orexigenic effect and also modifies locomotor activity, suggesting the involvement of ghrelin in feeding control and regulation of energy balance. Information derived from studies of ghrelin has been increasing, and important results have been obtained from both fish and mammals. Here, we present an overview of the effects of ghrelin on energy balance and psychomotor activity in the goldfish as an animal model. The available data provide an insight into evolutionary background of ghrelin's multiple actions on energy homeostasis in vertebrates.
Collapse
Affiliation(s)
- Ki Sung Kang
- Laboratory of Regulatory Biology, Graduate School of Science and Engineering, University of Toyama, 3190-Gofuku, Toyama 930-8555, Japan
| | - Satowa Yahashi
- Laboratory of Regulatory Biology, Graduate School of Science and Engineering, University of Toyama, 3190-Gofuku, Toyama 930-8555, Japan
| | - Kouhei Matsuda
- Laboratory of Regulatory Biology, Graduate School of Science and Engineering, University of Toyama, 3190-Gofuku, Toyama 930-8555, Japan
| |
Collapse
|
7
|
Kaufman MP, Forster HV. Reflexes Controlling Circulatory, Ventilatory and Airway Responses to Exercise. Compr Physiol 2011. [DOI: 10.1002/cphy.cp120110] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
|
8
|
Waldrop TG, Eldridge FL, Iwamoto GA, Mitchell JH. Central Neural Control of Respiration and Circulation During Exercise. Compr Physiol 2011. [DOI: 10.1002/cphy.cp120109] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
9
|
Anand A, Srivastava N, Raj H, Vijayan V. Influence of codeine on lobeline-induced respiratory reflexes and sensations and on ventilation with exercise in healthy subjects. Respir Physiol Neurobiol 2011; 175:169-75. [DOI: 10.1016/j.resp.2010.11.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2010] [Revised: 11/03/2010] [Accepted: 11/03/2010] [Indexed: 11/28/2022]
|
10
|
Anand A, Raj H, Gupta UA, Srivastava N. Influence of lower body negative pressure release on soleus H reflex, respiratory sensations and reflexes in human subjects. Respir Physiol Neurobiol 2010; 173:132-7. [DOI: 10.1016/j.resp.2010.06.017] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2010] [Revised: 06/30/2010] [Accepted: 06/30/2010] [Indexed: 10/19/2022]
|
11
|
Anand A, Roy A, Bhargava B, Raj H, Barde PB, Vijayan V. Early symptom-relief after valvulotomy in mitral stenosis indicates role of lobeline-sensitive intrapulmonary receptors. Respir Physiol Neurobiol 2009; 169:297-302. [DOI: 10.1016/j.resp.2009.09.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2009] [Revised: 08/23/2009] [Accepted: 09/14/2009] [Indexed: 11/25/2022]
|
12
|
Bilateral Vagotomy Inhibits Apnea and Attenuates Other Physiological Responses After Blunt Chest Trauma. ACTA ACUST UNITED AC 2008; 64:1420-6. [DOI: 10.1097/ta.0b013e318054e247] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
|
13
|
Ryan JL, Carroll JK, Ryan EP, Mustian KM, Fiscella K, Morrow GR. Mechanisms of cancer-related fatigue. Oncologist 2007; 12 Suppl 1:22-34. [PMID: 17573453 DOI: 10.1634/theoncologist.12-s1-22] [Citation(s) in RCA: 340] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Cancer-related fatigue (CRF) is one of the most prevalent symptoms patients with cancer experience, both during and after treatment. CRF is pervasive and affects patients' quality of life considerably. It is important, therefore, to understand the underlying pathophysiology of CRF in order to develop useful strategies for prevention and treatment. At present, the etiology of CRF is poorly understood and the relative contributions of the neoplastic disease, various forms of cancer therapy, and comorbid conditions (e.g., anemia, cachexia, sleep disorders, depression) remain unclear. In any individual, the etiology of CRF probably involves the dysregulation of several physiological and biochemical systems. Mechanisms proposed as underlying CRF include 5-HT neurotransmitter dysregulation, vagal afferent activation, alterations in muscle and ATP metabolism, hypothalamic-pituitary-adrenal axis dysfunction, circadian rhythm disruption, and cytokine dysregulation. Currently, these hypotheses are largely based on evidence from other conditions in which fatigue is a characteristic, in particular chronic fatigue syndrome and exercise-induced fatigue. The mechanisms that lead to fatigue in these conditions provide a theoretical basis for future research into the complex etiology of this distressing and debilitating symptom. An understanding of relevant mechanisms may offer potential routes for its prevention and treatment in patients with cancer.Disclosure of potential conflicts of interest is found at the end of this article.
Collapse
Affiliation(s)
- Julie L Ryan
- Department of Radiation Oncology, University of Rochester School of Medicine and Dentistry, James P Wilmot Cancer Center, Rochester, NY 14642, USA.
| | | | | | | | | | | |
Collapse
|
14
|
Romer LM, Dempsey JA. Effects of exercise-induced arterial hypoxaemia on limb muscle fatigue and performance. Clin Exp Pharmacol Physiol 2006; 33:391-4. [PMID: 16620307 DOI: 10.1111/j.1440-1681.2006.04361.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
1. Reductions in arterial O(2) saturation (-5% to -10%S(a)o(2) below rest) occur over time during sustained heavy-intensity exercise in a normoxic environment, caused primarily by the effects of acid pH and increased temperature on the position of the HbO(2) dissociation curve. 2. We prevented the desaturation incurred during exercise at approximately 90% VO(2 MAX) via increased fraction of inspired O(2) (F(i)o(2)) (0.23 to 0.29) and showed that exercise time to exhaustion was increased. 3. We used supramaximal magnetic stimulation (1-100 Hz) of the femoral nerve to test for quadriceps fatigue. We used mildly hyperoxic inspirates (F(i)o(2) 0.23 to 0.29) to prevent O(2) desaturation. We then compared the amount of quadriceps fatigue incurred following cycling exercise at S(a)o(2) 91% vs 98% with each trial carried out at identical work rates and for equal durations. 4. Preventing the normal exercise-induced O(2) desaturation prevented about one-half the amount of exercise-induced quadriceps fatigue; plasma lactate and effort perception were also reduced. In a subset of less fit subjects who showed only minimal arterial hypoxaemia during sustained exercise (S(a)o(2) approximately 95%), breathing a mildly hypoxic inspirate (F(i)o(2) 0.17; S(a)o(2) approximately 88%) exacerbated the quadriceps fatigue. 5. We conclude that the normal exercise-induced O(2) desaturation during heavy-intensity endurance exercise contributes significantly to exercise performance limitation in part because of its effect on locomotor muscle fatigue.
Collapse
Affiliation(s)
- Lee M Romer
- John Rankin Laboratory of Pulmonary Medicine, Department of Population Health Sciences, University of Wisconsin, Madison, Wisconsin 53706, USA
| | | |
Collapse
|
15
|
de Bisschop C, Montandon G, Guénard H. Expiratory muscles modulate negative expiratory pressure-induced flow during muscular exercise. Respir Physiol Neurobiol 2006; 154:453-66. [PMID: 16446126 DOI: 10.1016/j.resp.2005.12.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2005] [Revised: 12/22/2005] [Accepted: 12/23/2005] [Indexed: 10/25/2022]
Abstract
The recruitment of expiratory muscles during exercise might be altered by the application of negative expiratory pressure (NEP) inducing a feature of expiratory flow limitation (EFL) called muscle EFL. To check this hypothesis EFL and expiratory muscle EMG (ExpEMG) were measured at rest and during exercise in eight healthy subjects. Six subjects performed isocapnic hyperventilation. At 5hPa NEP, 5/8 subjects had EFL during exercise. This limitation disappeared when NEP value was increased and did not appear during isocapnic hyperventilation. During exercise, in limited subjects, ExpEMG was significantly reduced during expiration with NEP as compared to control. Gastric pressure measured in a limited subject increased during expiration but less with NEP than without it, while this pressure measured in another, non-limited, subject decreased. An inhibitory reflex due to negative pressure could be responsible for muscle EFL by reducing expiratory muscle activity. The response to NEP during exercise should be interpreted with caution.
Collapse
Affiliation(s)
- Claire de Bisschop
- Laboratoire des Adaptations Physiologiques aux Activités Physiques, Faculté des Sciences du Sport, UPRES EA 3813, 4 Allée Jean Monnet, 86000 POITIERS, France.
| | | | | |
Collapse
|
16
|
Romer LM, Dempsey JA, Lovering A, Eldridge M. Exercise-induced arterial hypoxemia: consequences for locomotor muscle fatigue. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2006; 588:47-55. [PMID: 17089878 DOI: 10.1007/978-0-387-34817-9_5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Reductions in arterial O2 saturation (-5 to -10% SaO2 < rest) occur over time during sustained heavy intensity exercise in a normoxic environment, due primarily to the effects of acid pH and increased temperature on the position of the HbO2 dissociation curve. We prevented the desaturation via increased F1O2 (.23 to .29) and showed that exercise time to exhaustion was increased. We used supramaximal magnetic stimulation (1 - 100 Hz) of the femoral nerve to test for quadriceps fatigue. We used mildly hyperoxic inspirates (F1O2 .23 to .29) to prevent O2 desaturation. We then compared the amount of quadriceps fatigue incurred following cycling exercise at SaO2 98% vs. 91% with each trial carried out at equal exercise intensities (90% Max) and for equal durations. Preventing the normal exercise-induced O2 desaturation prevented about one-half the amount of exercise-induced quadriceps fatigue; plasma lactate and effort perception were also reduced. We conclude that the normal exercise-induced O2 desaturation during heavy intensity endurance exercise contributes significantly to exercise performance limitation in part because of its effect on locomotor muscle fatigue. These effects of EIAH were confirmed in mild environmental hypoxia (FIO2 .17, SaO2 88%) which significantly augmented the magnitude of exercise-induced quadriceps fatigue observed in normoxia.
Collapse
Affiliation(s)
- Lee M Romer
- John Rankin Laboratory of Pulmonary Medicine, Department of Population Health Sciences, University of Wisconsin-Madison, USA
| | | | | | | |
Collapse
|
17
|
Krahl SE, Senanayake SS, Pekary AE, Sattin A. Vagus nerve stimulation (VNS) is effective in a rat model of antidepressant action. J Psychiatr Res 2004; 38:237-40. [PMID: 15003428 DOI: 10.1016/j.jpsychires.2003.11.005] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2003] [Revised: 10/18/2003] [Accepted: 11/18/2003] [Indexed: 11/25/2022]
Abstract
Depression is a common but debilitating illness that afflicts a large population and costs the US economy a staggering $40 billion dollars per year. Clinical studies have demonstrated that vagus nerve stimulation (VNS) is an effective treatment for medication-resistant depression. Understanding VNS's antidepressant mechanisms is key to improving the therapy and selecting the best surgical candidates, and demonstration that VNS is effective in a validated test of antidepressant activity allows us to elucidate these mechanisms in a cost-effective manner. In the present study, Wistar Kyoto rats were implanted with a cuff electrode on the left cervical vagus nerve. The next day, they were placed into a water-filled Plexiglas cylinder for 15 min. After this forced-swim session, one of three treatment conditions were administered over 4 consecutive days: 30 min per day of continuous VNS, 10 mg/kg of desipramine twice per day, or three daily electroconvulsive shocks (ECS). Yoked controls underwent sham procedures, but received no treatment. On the fourth day, the rats were given a 5-min, videotaped swim test. A blinded observer used the videotape to calculate the percentage of time that the rats were immobile (an index of depression) during the swim test. VNS significantly reduced immobility time as compared to unstimulated controls, indicating good antidepressant efficacy. This reduction did not differ statistically from that obtained from rats treated with either desipramine or ECS, two standard antidepressant treatments. These results indicate that VNS is an effective antidepressant in the forced-swim test, allowing us to now investigate possible therapeutic mechanisms.
Collapse
Affiliation(s)
- Scott E Krahl
- Neurology Service, VA Greater Los Angeles Healthcare System, Bldg. 114, Suite 217, 11301 Wilshire Blvd., Los Angeles, CA 90073, USA.
| | | | | | | |
Collapse
|
18
|
Dempsey JA, Sheel AW, Haverkamp HC, Babcock MA, Harms CA. [The John Sutton Lecture: CSEP, 2002]. Pulmonary system limitations to exercise in health. ACTA ACUST UNITED AC 2004; 28 Suppl:S2-24. [PMID: 14768314 DOI: 10.1139/h2003-066] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
It is commonly held that the structural capacity of the normal lung is "overbuilt" and exceeds the demand for pulmonary O2 and CO2 transport in the healthy, exercising human. On the other hand, the adaptability of pulmonary system structures to habitual physical training is substantially less than are other links in the O2 transport system. Accordingly, in some highly fit, and even in some not so fit habitually active individuals, the lung's diffusion surface, airways, and/or chest-wall musculature are underbuilt relative to the demand for maximal O2 transport. Two specific pulmonary limitations to exercise performance are proposed: (1) exercise-induced arterial hypoxemia secondary to excessive widening of the alveolar to arterial O2 difference, inadequate hyperventilation, and metabolic acidosis; and (2) highly fatiguing levels of respiratory muscle work which effectively steals blood flow from locomotor muscles via sympathetically mediated reflexes and heightens the perception of limb discomfort and dyspnea. In this brief review, we describe the characteristics and causes of each of these proposed pulmonary limitations and their consequences to maximal O2 uptake and exercise performance.
Collapse
Affiliation(s)
- Jerome A Dempsey
- Dept. of Population Health Sciences, John Rankin Laboratory of Pulmonary Medicine, University of Wisconsin-Madison, Madison, WI 53705, USA
| | | | | | | | | |
Collapse
|
19
|
Jou CJ, Farber JP, Qin C, Foreman RD. Intrapericardial algogenic chemicals evoke cardiac-somatic motor reflexes in rats. Auton Neurosci 2001; 94:52-61. [PMID: 11775708 DOI: 10.1016/s1566-0702(01)00345-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Many patients suffer from secondary muscle hyperalgesia after experiencing angina pectoris. Electrophysiological studies have also demonstrated electromyography (EMG) activities evoked during brief occlusion of the coronary artery in cats. Our objectives are: (1) to develop an animal model to study muscle changes resulting from cardiac dysfunction and (2) to investigate possible links between muscle hyperalgesia and EMG activities observed with ischemic heart diseases. Intrapericardial infusion of algogenic chemicals produced EMG activities in paraspinal muscles. Among these paraspinal muscles, the spinotrapezius produced the most consistent responses (38/53 animals). The evoked responses, in most cases, persisted longer than 90 s (29/53 muscles). The EMG activities consisted of three patterns of motor-unit discharge, namely single-unit, complex, and ventilation-related. The duration of the patterns, as well as the shape and amplitude of the motor-unit waveforms, are similar to the characteristics of muscle spasms. Since sensitization of muscle afferent fibers by noxious stimuli could produce angina-like pain, the spasm-like EMG activities might sensitize muscle afferent fibers that contribute to acute angina pain and secondary muscle hyperalgesia of cardiac patients.
Collapse
Affiliation(s)
- C J Jou
- Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City 73190, USA.
| | | | | | | |
Collapse
|
20
|
Jou CJ, Farber JP, Qin C, Foreman RD. Afferent pathways for cardiac-somatic motor reflexes in rats. Am J Physiol Regul Integr Comp Physiol 2001; 281:R2096-102. [PMID: 11705797 DOI: 10.1152/ajpregu.2001.281.6.r2096] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The present study used a rat model in which algogenic chemicals were infused into the pericardial sac to evoke spasmlike contractions in paraspinal muscles. The following techniques were used to study the roles of sympathetic (SCA) and vagal cardiac afferents (VCA) in electromyographic (EMG) responses to pericardial algogenic chemicals: chemical stimulation, electrical stimulation, and nerve transection. Activation with bradykinin (n = 46) produced a significantly higher peak response than infusion of an algogenic mixture (n = 53) containing chemicals that also activate VCA. Electrical stimulation of SCA produced bilateral EMG activities (7 of 7). Electrical stimulation of VCA did not evoke EMG activity but inhibited the chemically evoked EMG response (12 of 12). The chemically evoked response was decreased after transection of the left sympathetic chain (n = 22) and was increased after bilateral vagotomy (n = 19). These results suggest an excitatory and inhibitory role for SCA and VCA, respectively. Therefore, in addition to spinothalamic convergence of somatic and visceral afferents, activation of SCA to generate spasmlike muscle contractions could account in part for anginal pain, and VCA activation could attenuate this effect.
Collapse
Affiliation(s)
- C J Jou
- Department of Physiology, University of Oklahoma Health Sciences Center, PO Box 26901, Oklahoma City, OK 73190, USA.
| | | | | | | |
Collapse
|
21
|
Abstract
Muscle fatigue is an exercise-induced reduction in maximal voluntary muscle force. It may arise not only because of peripheral changes at the level of the muscle, but also because the central nervous system fails to drive the motoneurons adequately. Evidence for "central" fatigue and the neural mechanisms underlying it are reviewed, together with its terminology and the methods used to reveal it. Much data suggest that voluntary activation of human motoneurons and muscle fibers is suboptimal and thus maximal voluntary force is commonly less than true maximal force. Hence, maximal voluntary strength can often be below true maximal muscle force. The technique of twitch interpolation has helped to reveal the changes in drive to motoneurons during fatigue. Voluntary activation usually diminishes during maximal voluntary isometric tasks, that is central fatigue develops, and motor unit firing rates decline. Transcranial magnetic stimulation over the motor cortex during fatiguing exercise has revealed focal changes in cortical excitability and inhibitability based on electromyographic (EMG) recordings, and a decline in supraspinal "drive" based on force recordings. Some of the changes in motor cortical behavior can be dissociated from the development of this "supraspinal" fatigue. Central changes also occur at a spinal level due to the altered input from muscle spindle, tendon organ, and group III and IV muscle afferents innervating the fatiguing muscle. Some intrinsic adaptive properties of the motoneurons help to minimize fatigue. A number of other central changes occur during fatigue and affect, for example, proprioception, tremor, and postural control. Human muscle fatigue does not simply reside in the muscle.
Collapse
Affiliation(s)
- S C Gandevia
- Prince of Wales Medical Research Institute, Prince of Wales Hospital and University of New South Wales, Randwick, Sydney, Australia.
| |
Collapse
|
22
|
Butler JE, Anand A, Crawford MR, Glanville AR, McKenzie DK, Paintal AS, Taylor JL, Gandevia SC. Changes in respiratory sensations induced by lobeline after human bilateral lung transplantation. J Physiol 2001; 534:583-93. [PMID: 11454974 PMCID: PMC2278721 DOI: 10.1111/j.1469-7793.2001.00583.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
1. The sensations evoked by the injection of lobeline into the right antecubital vein were studied in 8 subjects after bilateral lung transplantation and 10 control subjects. In control subjects, two distinct sensations were experienced. There was an early noxious sensation (onset approximately 10 s) followed by a late sensation of breathlessness (onset approximately 26 s) associated with involuntary hyperventilation. The early sensation was accompanied by respiratory and cardiovascular changes. 2. In contrast to control subjects, the early respiratory events and the noxious sensations evoked by injections of lobeline (18-60 microg kg(-1)) did not occur in subjects with recent bilateral lung transplantation. This suggests that the early respiratory sensations are mediated by the discharge of receptors in the lungs. 3. The late hyperventilation and the accompanying sensation of breathlessness occurred in both transplant and control subjects and are therefore likely to be mediated by receptors elsewhere in the body, presumably systemic arterial chemoreceptors stimulated by lobeline. 4. In control subjects, but not transplant subjects, there was a consistent decrease in mean arterial pressure associated with the lobeline injection. This suggests that pulmonary afferents mediate the hypotension. 5. For transplant subjects studied more than a year after transplantation, there was some evidence that the noxious respiratory sensations evoked by lobeline had returned. This suggests that some functional reinnervation of pulmonary afferents may occur.
Collapse
Affiliation(s)
- J E Butler
- Prince of Wales Medical Research Institute, University of New South Wales, Sydney, Australia
| | | | | | | | | | | | | | | |
Collapse
|
23
|
Lee LY, Pisarri TE. Afferent properties and reflex functions of bronchopulmonary C-fibers. RESPIRATION PHYSIOLOGY 2001; 125:47-65. [PMID: 11240152 DOI: 10.1016/s0034-5687(00)00204-8] [Citation(s) in RCA: 286] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Bronchopulmonary C-fiber afferents are characterized by their distinct sensitivity to chemical stimuli in the airways or pulmonary circulation. Responses evoked by activating these afferents are mediated by both central reflex pathways and by local or axon reflexes involving the release of tachykinins from sensory endings. Bronchopulmonary C-fiber stimulation reflexly reduces tidal volume and increases respiratory rate, constricts the airways, increases mucus secretion in the airways, and is associated with coughing. Cardiovascular effects include bradycardia, a fall in cardiac output, and bronchial vasodilation that increases airway blood flow despite systemic hypotension. In animals, C-fiber stimulation inhibits skeletal muscle activity, and in humans, is accompanied by burning and choking sensations in the throat and upper chest. Recent studies have identified additional physiologic and pharmacologic stimuli to these afferents, such as hydrogen ions, adenosine, reactive oxygen species, and hyperosmotic solutions. Furthermore, increasing evidence indicates that the excitability of these afferents is enhanced by the local release of certain autocoids (e.g. PGE2) during airway inflammation. These findings further indicate that vagal C-fiber endings in the lungs and airways play an important role in regulating the cardiopulmonary functions under both normal and abnormal physiologic conditions.
Collapse
Affiliation(s)
- L Y Lee
- Department of Physiology, University of Kentucky Medical Center, Lexington, KY 40536-0298, USA.
| | | |
Collapse
|
24
|
MacLean DA, Vickery LM, Sinoway LI. Elevated interstitial adenosine concentrations do not activate the muscle reflex. Am J Physiol Heart Circ Physiol 2001; 280:H546-53. [PMID: 11158950 DOI: 10.1152/ajpheart.2001.280.2.h546] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The purpose of the present study was to examine the effects of adenosine perfusion of the isolated triceps surae muscle group in the decerebrate cat on interstitial adenosine concentrations as well as heart rate and blood pressure responses. In six male cats (6.0 +/- 0.21 kg), the triceps surae muscle group of both legs was perfused with an artificial blood solution containing no additives (control) and then with blood containing 20 mM or 100 microM adenosine for 10 min. An intact muscle reflex was confirmed by bolus injections of 50 mM phosphate and/or saturated KCl administered into the triceps surae muscle via the cannulated popliteal artery before and after adenosine blood perfusion. Microdialysis of the triceps surae muscle group during muscle perfusion revealed that interstitial adenosine was elevated (P < 0.05) from 0.9 +/- 0.3 microM during control blood perfusion to 2,421 +/- 547 microM during 20 mM adenosine perfusion. In addition, interstitial adenosine levels were increased (P < 0.05) from 1.1 +/- 0.3 microM during control blood perfusion to 4.1 +/- 1.2 microM during perfusion with 100 microM adenosine. Despite the large increases in interstitial adenosine levels, perfusion of the triceps surae muscle group with the two blood adenosine solutions resulted in no significant increases in heart rate or blood pressure. These data strongly suggest that elevated interstitial adenosine concentrations do not play a role in activating the muscle reflex and confirm our previous in vivo human findings (J Appl Physiol 83: 1045-1053, 1997).
Collapse
Affiliation(s)
- D A MacLean
- Division of Cardiology, Department of Medicine, The Pennsylvania State University College of Medicine, The Milton S. Hershey Medical Center, Hershey Pennsylvania, 17033, USA.
| | | | | |
Collapse
|
25
|
Gandevia SC, Taylor JL, Butler JE. Stopping Exercise: Role of Pulmonary C Fibers and Inhibition Of Motoneurons. NEWS IN PHYSIOLOGICAL SCIENCES : AN INTERNATIONAL JOURNAL OF PHYSIOLOGY PRODUCED JOINTLY BY THE INTERNATIONAL UNION OF PHYSIOLOGICAL SCIENCES AND THE AMERICAN PHYSIOLOGICAL SOCIETY 2000; 15:241-245. [PMID: 11390918 DOI: 10.1152/physiologyonline.2000.15.5.241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In animals, the J reflex evoked by pulmonary C fibers provides potent inhibition of limb muscles and would act to limit exercise. However, recent work shows that although activation of these fibers causes severe respiratory discomfort, it does not impair the output of limb motoneurons to voluntary, reflex, or locomotor drives in awake humans.
Collapse
Affiliation(s)
- Simon C. Gandevia
- Prince of Wales Medical Research Institute and University of New South Wales, Sydney, 2031 Australia
| | | | | |
Collapse
|
26
|
Silber DH, Sinoway LI, Leuenberger UA, Amassian VE. Magnetic stimulation of the human motor cortex evokes skin sympathetic nerve activity. J Appl Physiol (1985) 2000; 88:126-34. [PMID: 10642372 DOI: 10.1152/jappl.2000.88.1.126] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Single-pulse magnetic coil stimulation (Cadwell MES 10) over the cranium induces without pain an electric pulse in the underlying cerebral cortex. Stimulation over the motor cortex can elicit a muscle twitch. In 10 subjects, we tested whether motor cortical stimulation could also elicit skin sympathetic nerve activity (SSNA; n = 8) and muscle sympathetic nerve activity (MSNA; n = 5) in the peroneal nerve. Focal motor cortical stimulation predictably elicited bursts of SSNA but not MSNA; with successive stimuli, the SSNA responses did not readily extinguish (94% of discharges to the motor cortex evoked SSNA responses) and had predictable latencies [739 +/- 33 (SE) to 895 +/- 13 ms]. The SSNA responses were similar after stimulation of dominant and nondominant sides. Focal stimulation posterior to the motor cortex elicited extinguishable SSNA responses. In three of six subjects, anterior cortical stimulation evoked SSNA responses similar to those seen with motor cortex stimulation but without detectable movement; in the other subjects, anterior stimulation evoked less SSNA discharge than that seen with motor cortex stimulation. Contrasting with motor cortical stimulation, evoked SSNA responses were more readily extinguished with 1) peripheral stimulation that directly elicited forearm muscle activation accompanied by electromyograms similar to those with motor cortical stimulation; 2) auditory stimulation by the click of the energized coil when off the head; and 3) in preliminary experiments, finger afferent stimulation sufficient to cause tingling. Our findings are consistent with the hypothesis that motor cortex stimulation can cause activation of both alpha-motoneurons and SSNA.
Collapse
Affiliation(s)
- D H Silber
- Section of Cardiology, The Milton S. Hershey Medical Center, The Pennsylvania State University, Hershey 17033, USA
| | | | | | | |
Collapse
|
27
|
MacLean DA, LaNoue KF, Gray KS, Sinoway LI. Effects of hindlimb contraction on pressor and muscle interstitial metabolite responses in the cat. J Appl Physiol (1985) 1998; 85:1583-92. [PMID: 9760357 DOI: 10.1152/jappl.1998.85.4.1583] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We used the microdialysis technique to measure the interstitial concentration of several putative metabolic stimulants of the exercise pressor reflex during 3- and 5-Hz twitch contractions in the decerebrate cat. The peak increases in heart rate and mean arterial pressure during contraction were 20 +/- 5 beats/min and 21 +/- 8 mmHg and 27 +/- 9 beats/min and 37 +/- 12 mmHg for the 3- and 5-Hz stimulation protocols, respectively. All variables returned to baseline after 10 min of recovery. Interstitial lactate rose (P < 0. 05) by 0.41 +/- 0.15 and 0.56 +/- 0.16 mM for the 3- and 5-Hz stimulation protocols, respectively, and were not statistically different from one another. Interstitial lactate levels remained above (P < 0.05) baseline during recovery in the 5-Hz group. Dialysate phosphate concentrations (corrected for shifts in probe recovery) rose with stimulation (P < 0.05) by 0.19 +/- 0.08 and 0.11 +/- 0.03 mM for the 3- and 5-Hz protocols. There were no differences between groups. The resting dialysate K+ concentrations for the 3- and 5-Hz conditions were 4.0 +/- 0.1 and 3.9 +/- 0.1 meq/l, respectively. During stimulation the dialysate K+ concentrations rose steadily for both conditions, and the increase from rest to stimulation (P < 0.05) was 0.57 +/- 0.19 and 0.81 +/- 0.06 meq/l for the 3- and 5-Hz conditions, respectively, with no differences between groups. Resting dialysate pH was 6.915 +/- 0.055 and 6.981 +/- 0.032 and rose to 7.013 (P < 0.05) and 7.053 (P < 0.05) for the 3- and 5-Hz conditions, respectively, and then became acidotic (6. 905, P < 0.05) during recovery (5 Hz only). This study represents the first time simultaneous measurements of multiple skeletal muscle interstitial metabolites and pressor responses to twitch contractions have been made in the cat. These data suggest that interstitial K+ and phosphate, but not lactate and H+, may contribute to the stimulation of thin fiber muscle afferents during contraction.
Collapse
Affiliation(s)
- D A MacLean
- Section of Cardiology, The Pennsylvania State University College of Medicine, The Milton S. Hershey Medical Center, Hershey 17033, Pennsylvania, USA
| | | | | | | |
Collapse
|
28
|
Pickar JG. The thromboxane A2 mimetic U-46619 inhibits somatomotor activity via a vagal reflex from the lung. THE AMERICAN JOURNAL OF PHYSIOLOGY 1998; 275:R706-12. [PMID: 9728066 DOI: 10.1152/ajpregu.1998.275.3.r706] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Vagal reflexes from the heart and lungs elicit autonomic as well as somatomotor responses. The purpose of the present investigation was to determine whether the inflammatory mediator thromboxane A2 inhibits the knee-jerk reflex via a vagally mediated reflex from either the heart or the lung. The thromboxane A2 mimetic U-46619 (0. 8 +/- 0.08 microg/kg) was injected through a catheter placed near the right atrium (n = 11), near the aortic arch (n = 7), or into the pericardial sac (n = 4) in 11 chloralose-anesthetized cats. The knee-jerk reflex, elicited by striking the patellar tendon with a solenoid-driven hammer, was used to evaluate somatomotor activity. The mean maximum tension produced by the knee-jerk reflex was 306 +/- 21 g (range 154-471 g). Intravenous U-46619 injection inhibited the knee-jerk reflex by 25 +/- 6% and increased peak systolic pressure 53 +/- 7 mmHg on average. Bilateral cervical vagotomy abolished the somatomotor inhibition but did not reduce the pressor response. Intra-arterial U-46619 injection inhibited the knee-jerk reflex in two of seven cats and increased peak systolic pressure by 41 +/- 11 mmHg. Vagotomy abolished the inhibition in one of the two cats but did not reduce the pressor response. Intrapericardial U-46619 injection did not affect the knee-jerk reflex nor blood pressure. The results indicate that U-46619 inhibited the knee-jerk reflex via a vagal reflex from the lung because the inhibition predominated after intravenous injection and was abolished by vagotomy. Speculation is made that the inflammatory mediator thromboxane A2 may contribute via a vagal reflex to the depression of motor activity associated with sickness behavior.
Collapse
Affiliation(s)
- J G Pickar
- Department of Anatomy and Physiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas 66506, USA
| |
Collapse
|
29
|
Gandevia SC, Butler JE, Taylor JL, Crawford MR. Absence of viscerosomatic inhibition with injections of lobeline designed to activate human pulmonary C fibres. J Physiol 1998; 511 ( Pt 1):289-300. [PMID: 9679182 PMCID: PMC2231107 DOI: 10.1111/j.1469-7793.1998.289bi.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
1. Activation of pulmonary C fibres (J receptors) in animals produces inhibition of spinal motoneurones. Intravenous bolus injections of lobeline are believed to activate pulmonary C fibres (J receptors) in human subjects and to produce characteristic sensations and cardiorespiratory responses. This study quantified the respiratory sensations evoked by such injections and then used a range of suprathreshold doses of lobeline and tested for the presence of reflex or descending inhibition of motoneuronal output. 2. Injections of lobeline produced dose-dependent sensations of respiratory discomfort referred to the throat and upper chest beginning within about 10 s and often associated with coughing. As the dose increased the latency for the sensations decreased while their duration and intensity increased. Reflex changes in blood pressure, heart rate and ventilation also occurred. 3. Injections of lobeline at doses sufficient to evoke respiratory discomfort lasting 25-32 s (37-73 microgram kg-1) increased the size of the H reflex in soleus with an onset latency of about 10 s and lasting about 20 s. 4. The size of EMG responses evoked in upper limb muscles by transcranial magnetic stimulation of the motor cortex increased shortly after injections and remained elevated for about 30-35 s. 5. Injections of lobeline during sustained voluntary contractions of the elbow flexors at submaximal or maximal levels did not impair the ability to produce force. 6. Walking was not disrupted by repeated suprathreshold doses of lobeline. 7. It is concluded that injections of lobeline sufficient to evoke cardiorespiratory reflexes and sensations of severe respiratory discomfort are not associated with functionally important inhibition of motor performance. The results cast doubt on the ability of the J reflex to limit exercise in humans.
Collapse
Affiliation(s)
- S C Gandevia
- Prince of Wales Medical Research Institute and Department of Clinical Neurophysiology, Prince of Wales Hospital and University of New South Wales, Sydney, NSW 2031, Australia.
| | | | | | | |
Collapse
|
30
|
Balzamo E, Vuillon-Cacciuttolo G, Burnet H, Jammes Y. Influence of respiratory afferents upon the proprioceptive reflex of skeletal muscles in healthy humans. Neurosci Lett 1997; 236:127-30. [PMID: 9406753 DOI: 10.1016/s0304-3940(97)00782-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Relationships between respiratory afferents and the motor drive to skeletal muscles are well documented in animals, but human data are scarce. Tonic vibratory response (TVR) elicited by mechanical tendon vibrations were explored in an arm (extensor digitorum, ED) and a leg (vastus lateralis, VL) muscle, in healthy subjects. Tendon vibrations were delivered during unloaded breathing and after 10 breathing cycles while the subject breathed through an inspiratory or expiratory resistive load in order to activate respiratory afferents. Inspiratory loaded breathing significantly enhanced TVR in ED and VL muscles whereas the effects of expiratory loading depended on the vibrated muscle (increased TVR in ED; decreased TVR in VL). These results suggest that inspiratory muscle afferents activated during inspiratory loading facilitate the gamma motor drive to arm and leg muscles whereas the activation of pulmonary vagal afferents during expiratory loading can exert a facilitating or suppressive influence on the gamma motor drive, depending on the limb muscle group.
Collapse
Affiliation(s)
- E Balzamo
- Laboratoire de Physiopathologie Respiratoire Cellulaire et Intégrée ER-CNRS 6095/UPRES-EA 2201, Institut Jean Roche, Faculté de Médecine Nord, Marseille, France
| | | | | | | |
Collapse
|
31
|
Pickar JG. Chemical stimulation of cardiac receptors attenuates locomotion in mesencephalic cats. J Appl Physiol (1985) 1997; 83:113-9. [PMID: 9216952 DOI: 10.1152/jappl.1997.83.1.113] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The purpose of the present investigation was to determine whether chemical stimulation of cardiac receptors is sufficient to inhibit locomotion. Decerebrate, unanesthetized cats were induced to walk on a treadmill by electrically stimulating the mesencephalic locomotor region (MLR). Cardiac receptors were stimulated by injecting nicotine (62.3 +/- 8.6 microg/kg, mean +/- SE) into the pericardial sac. Cardiac nerve activity was reversibly blocked by injecting procaine (2%) into the pericardial sac. Locomotion was monitored by using bipolar needle electrodes inserted into the lateral gastrocnemius (LG) and tibialis anterior (TA) muscles. Integrated electromyographic (iEMG) activity from each muscle was quantified on a step-by-step basis. Intrapericardial (ipc) nicotine inhibited locomotion and evoked the coronary chemoreflex. Blood pressure and heart rate decreased significantly by 45.6 +/- 7.1 mmHg and 59.3 +/- 12.3 beats/min, respectively. Nicotine ipc significantly reduced iEMG activity by 24-28% in the LG muscles. The TA muscles were not affected consistently by ipc nicotine. The locomotor inhibition and the depressor reflex paralleled each other and occurred within 5 s of nicotine injection. Procaine ipc blocked the nicotine-induced locomotor inhibition and depressor reflex. The effects of procaine were largely reversible, because ipc nicotine reduced iEMG activity in the LG (25-46%) but not in the TA muscles after washing procaine from the pericardial sac. These results demonstrate that cardiac receptors sensitive to nicotine inhibit MLR-induced locomotion in the decerebrate cat. These findings indicate the presence of a neural pathway from the heart whereby endogenous stimuli could reflexly alter motor control.
Collapse
Affiliation(s)
- J G Pickar
- Department of Anatomy and Physiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas 66506, USA
| |
Collapse
|
32
|
Fontanari P, Vuillon-Cacciuttolo G, Balzamo E, Zattara-Hartmann MC, Lagier-Tessonnier F, Jammes Y. Resistive loaded breathing changes the motor drive to arm and leg muscles in man. Neurosci Lett 1996; 210:130-4. [PMID: 8783291 DOI: 10.1016/0304-3940(96)12564-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Breathing through inspiratory or expiratory resistive loads activates respiratory afferents. In healthy individuals, we explored the recruitment of motor units in arm (adductor pollicis, AP and biceps branchialis, BB) and leg (vastus lateralis, VL) muscle groups during voluntary contractions sustained at 80% of maximal force. Quantitative EMG analysis consisted of measurement of energies in high (EH) and low (EL) frequency bands. EH and EL changes were measured at constant time, i.e. 10 and 20 s after the onset of plateau contraction. The resistive load was added to the inspiratory or the expiratory circuit for 10-min periods. Its value was high but not enough to induce changes in blood gases and blood pressure. Compared to muscle contractions performed during non-loaded breathing periods, inspiratory loading did not affect BB and VL contractions, whereas it induced significant changes in AP contraction, characterized by enhanced variations in EL value measured at 10 s. Expiratory loading affected solely the VP contraction. Then, EH decreased at 10 and 20 s while it increased always when VP contractions were executed during non-loaded breathing. Expiratory loading elevated the functional residual capacity (FRC), but the load-induced changes in VL contraction persisted when subjects adjusted their FRC to the control level. These data suggest that respiratory afferents influence the skeleto-motor drive. Thus, viscero-somatic reflex may be present in patients with severe obstructive pulmonary disease.
Collapse
Affiliation(s)
- P Fontanari
- Laboratoire de Physiopathologie Respiratoire Intégrée et Cellulaire, URA 1630, Institut Jean Roche, Faculté de Médecine, Université de la Méditerrannée, Marseille, France
| | | | | | | | | | | |
Collapse
|
33
|
Paintal AS. Some recent advances in studies on J receptors. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1995; 381:15-25. [PMID: 8867819 DOI: 10.1007/978-1-4615-1895-2_2] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
While describing recent advances in studies on J receptors it was shown that the discovery of the principle of the relative dilution of multiple solutes in flowing fluids paved the way for developing a new method for measuring in vivo the concentration of injected drugs in the blood of the pulmonary artery. This led to the finding that excitatory solutes move out of the capillaries through a process of diffusion not through filtration. Increase in the permeability of the capillaries causes a marked increase in the responses of the J receptors to excitants by causing greater movement of the excitants to the receptors. This information is likely to yield a method for distinguishing permeability edema from hamodynamic edema in man. The most recent advance relates to the evidence showing conclusively that the sensations and dry cough produced by injecting lobeline intravenouly in man is due to the stimulation of the J receptors. The slowly and rapidly adapting receptors play little or no role in this. The nature of the sensations felt is somewhat variable, most commonly it is choking and pressure localised in the throat and upper chest. Similar sensations are felt by subjects with high altitude pulmonary edema (HAPE). From this data it is extrapolated that the same kinds of sensations that accompany breathlessness after moderate or severe exercise at sea level are also J receptor induced.
Collapse
Affiliation(s)
- A S Paintal
- DST Centre for Visceral Mechanisms, Delhi University, India
| |
Collapse
|