1
|
Cohen JN, Samra RA, Au JS. Supporting evidence for an "arterial pump" venous return mechanism in humans. J Appl Physiol (1985) 2023; 135:1120-1125. [PMID: 37823204 DOI: 10.1152/japplphysiol.00480.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Revised: 09/27/2023] [Accepted: 10/05/2023] [Indexed: 10/13/2023] Open
Abstract
Blood flow in large veins is dependent on arterial-atrial pressure gradients and pumping mechanisms in concert with valve recruitment. Classic descriptions of muscle and respiratory pumps describe venous transmural pressure changes that cause flow. Not often considered is the transmission of pulsatile energy from arteries to veins directly adjacent to each other. Recently, an ex vivo study demonstrated a novel arterial pump effect in venoarterial bundles when valves were active in managing venous flow. We sought to show in vivo evidence of this arterial pump mechanism in 16 healthy young adults. Venous blood flow was measured in the venoarterial bundled deep femoral vein (DFV) and the greater saphenous vein (GSV), which is not bundled with an artery. Veins were studied through randomized body positions of -6° head-down tilt (HDT), supine, 20° head-up tilt (HUT), and 40° HUT, with the assumption that greater HUT postures increased valve dependence to observe the arterial pump effect. Between 20° and 40° HUT conditions, bundled DFV blood flow did not change (68 ± 36 vs. 71 ± 56 mL·min-1; Padj > 0.99), whereas nonbundled GSV blood flow decreased (6.1 ± 4.8 vs. 3.5 ± 3.9 mL·min-1; P = 0.01). Diameters between 20° and 40° HUT conditions increased in DFV (0.90 ± 0.16 vs. 1.04 ± 0.19 cm; P < 0.01), but not in GSV (0.33 ± 0.10 vs. 0.32 ± 0.08 cm; P = 0.60). These data support previous ex vivo observations that when venous pressure gradients rely on valve recruitment, presence of an adjacent artery may protect against further decreases in blood flow. The arterial pump mechanism is an underappreciated contributor to venous return and warrants further investigation.NEW & NOTEWORTHY Venous return mechanisms have classically considered muscle and respiratory pumps; however, recent ex vivo evidence suggests that pulsatile energy imparted from arteries to adjacent bundled veins can increase venous flow under certain driving pressures. We tested this concept in humans by manipulating hydrostatic pressures and measuring flow in bundled and nonbundled veins. The bundled vein exhibited flow preservation at the highest hydrostatic pressure. We suggest a novel conservation of energy mechanism within the circulatory system.
Collapse
Affiliation(s)
- Jeremy N Cohen
- Department of Kinesiology and Health Sciences, University of Waterloo, Waterloo, Ontario, Canada
| | - Rose A Samra
- Department of Kinesiology and Health Sciences, University of Waterloo, Waterloo, Ontario, Canada
| | - Jason S Au
- Department of Kinesiology and Health Sciences, University of Waterloo, Waterloo, Ontario, Canada
| |
Collapse
|
2
|
Rytel L, Könyves L, Gonkowski S. Endocrine Disruptor Bisphenol a Affects the Neurochemical Profile of Nerve Fibers in the Aortic Arch Wall in the Domestic Pig. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:ijerph19105964. [PMID: 35627499 PMCID: PMC9140835 DOI: 10.3390/ijerph19105964] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Revised: 05/09/2022] [Accepted: 05/11/2022] [Indexed: 02/01/2023]
Abstract
Bisphenol A (BPA) is a synthetic compound utilized in industry for the production of various plastics. BPA penetrates into the environment and adversely affects living organisms. Therefore, the influence of various BPA dosages on the neurochemical characteristics of nerve fibers located in the aortic branch wall was investigated in this study utilizing a double immunofluorescence method. It was found that BPA in concentration of 0.5 mg/kg body weight/day causes a clear increase in the density of nerves within aortic branch walls immunoreactive to cocaine- and amphetamine-regulated transcript (CART), calcitonin gene-related peptide (CGRP), neuronal isoform of nitric oxide synthase (nNOS), pituitary adenylate cyclase-activating peptide (PACAP), and vasoactive intestinal polypeptide (VIP). Nerves containing galanin (GAL) and/or somatostatin (SOM) did not change when BPA was introduced into the system. Changes noted after administration of BPA at a dose of 0.05 mg/kg body weight/day were less visible and concerned fibers immunoreactive to CART, CGRP, and/or PACAP. The obtained results show that BPA affects the neurochemical coding of nerves in the aortic branch wall. These fluctuations may be the first signs of the influence of this substance on blood vessels and may also be at the root of the disturbances in the cardiovascular system.
Collapse
Affiliation(s)
- Liliana Rytel
- Department of Internal Disease with Clinic, Faculty of Veterinary Medicine, University of Warmia and Mazury, ul. Oczapowskiego 14, 10-719 Olsztyn, Poland
- Correspondence:
| | - László Könyves
- Department of Animal Hygiene, Herd Health and Mobile Clinic, University of Veterinary Medicine, 1078 Budapest, Hungary;
| | - Slawomir Gonkowski
- Department of Clinical Physiology, Faculty of Veterinary Medicine, University of Warmia and Mazury, 10-719 Olsztyn, Poland;
| |
Collapse
|
3
|
Guo Z, Zhang H, Chen Z, van der Plas E, Gutmann L, Thedens D, Nopoulos P, Sonka M. Fully automated 3D segmentation of MR-imaged calf muscle compartments: Neighborhood relationship enhanced fully convolutional network. Comput Med Imaging Graph 2021; 87:101835. [PMID: 33373972 PMCID: PMC7855601 DOI: 10.1016/j.compmedimag.2020.101835] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2020] [Revised: 08/26/2020] [Accepted: 11/17/2020] [Indexed: 11/24/2022]
Abstract
Automated segmentation of individual calf muscle compartments from 3D magnetic resonance (MR) images is essential for developing quantitative biomarkers for muscular disease progression and its prediction. Achieving clinically acceptable results is a challenging task due to large variations in muscle shape and MR appearance. In this paper, we present a novel fully convolutional network (FCN) that utilizes contextual information in a large neighborhood and embeds edge-aware constraints for individual calf muscle compartment segmentations. An encoder-decoder architecture is used to systematically enlarge convolution receptive field and preserve information at all resolutions. Edge positions derived from the FCN output muscle probability maps are explicitly regularized using kernel-based edge detection in an end-to-end optimization framework. Our method was evaluated on 40 T1-weighted MR images of 10 healthy and 30 diseased subjects by fourfold cross-validation. Mean DICE coefficients of 88.00-91.29% and mean absolute surface positioning errors of 1.04-1.66 mm were achieved for the five 3D muscle compartments.
Collapse
Affiliation(s)
- Zhihui Guo
- Iowa Institute for Biomedical Imaging, University of Iowa, Iowa City, IA 52242, USA.
| | - Honghai Zhang
- Iowa Institute for Biomedical Imaging, University of Iowa, Iowa City, IA 52242, USA
| | - Zhi Chen
- Iowa Institute for Biomedical Imaging, University of Iowa, Iowa City, IA 52242, USA
| | | | - Laurie Gutmann
- Department of Neurology, University of Iowa, Iowa City, IA 52242, USA
| | - Daniel Thedens
- Department of Psychiatry, University of Iowa, Iowa City, IA 52242, USA
| | - Peggy Nopoulos
- Department of Psychiatry, University of Iowa, Iowa City, IA 52242, USA
| | - Milan Sonka
- Iowa Institute for Biomedical Imaging, University of Iowa, Iowa City, IA 52242, USA
| |
Collapse
|
4
|
Goswami N, Blaber AP, Hinghofer-Szalkay H, Montani JP. Orthostatic Intolerance in Older Persons: Etiology and Countermeasures. Front Physiol 2017; 8:803. [PMID: 29163185 PMCID: PMC5677785 DOI: 10.3389/fphys.2017.00803] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Accepted: 09/29/2017] [Indexed: 12/16/2022] Open
Abstract
Orthostatic challenge produced by upright posture may lead to syncope if the cardiovascular system is unable to maintain adequate brain perfusion. This review outlines orthostatic intolerance related to the aging process, long-term bedrest confinement, drugs, and disease. Aging-associated illness or injury due to falls often leads to hospitalization. Older patients spend up to 83% of hospital admission lying in bed and thus the consequences of bedrest confinement such as physiological deconditioning, functional decline, and orthostatic intolerance represent a central challenge in the care of the vulnerable older population. This review examines current scientific knowledge regarding orthostatic intolerance and how it comes about and provides a framework for understanding of (patho-) physiological concepts of cardiovascular (in-) stability in ambulatory and bedrest confined senior citizens as well as in individuals with disease conditions [e.g., orthostatic intolerance in patients with diabetes mellitus, multiple sclerosis, Parkinson's, spinal cord injury (SCI)] or those on multiple medications (polypharmacy). Understanding these aspects, along with cardio-postural interactions, is particularly important as blood pressure destabilization leading to orthostatic intolerance affects 3-4% of the general population, and in 4 out of 10 cases the exact cause remains elusive. Reviewed also are countermeasures to orthostatic intolerance such as exercise, water drinking, mental arithmetic, cognitive training, and respiration training in SCI patients. We speculate that optimally applied countermeasures such as mental challenge maintain sympathetic activity, and improve venous return, stroke volume, and consequently, blood pressure during upright standing. Finally, this paper emphasizes the importance of an active life style in old age and why early re-mobilization following bedrest confinement or bedrest is crucial in preventing orthostatic intolerance, falls and falls-related injuries in older persons.
Collapse
Affiliation(s)
- Nandu Goswami
- Gravitational Physiology and Medicine Research Unit, Institute of Physiology, Medical University of Graz, Graz, Austria
| | - Andrew P Blaber
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
| | - Helmut Hinghofer-Szalkay
- Gravitational Physiology and Medicine Research Unit, Institute of Physiology, Medical University of Graz, Graz, Austria
| | - Jean-Pierre Montani
- Department of Medicine/Physiology, University of Fribourg, Fribourg, Switzerland
| |
Collapse
|
5
|
Xu D, Verma AK, Garg A, Bruner M, Fazel-Rezai R, Blaber AP, Tavakolian K. Significant role of the cardiopostural interaction in blood pressure regulation during standing. Am J Physiol Heart Circ Physiol 2017. [PMID: 28626082 DOI: 10.1152/ajpheart.00836.2016] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cardiovascular and postural control systems have been studied independently despite the increasing evidence showing the importance of cardiopostural interaction in blood pressure regulation. In this study, we aimed to assess the role of the cardiopostural interaction in relation to cardiac baroreflex in blood pressure regulation under orthostatic stress before and after mild exercise. Physiological variables representing cardiovascular control (heart rate and systolic blood pressure), lower limb muscle activation (electromyography), and postural sway (center of pressure derived from force and moment data during sway) were measured from 17 healthy participants (25 ± 2 yr, 9 men and 8 women) during a sit-to-stand test before and after submaximal exercise. The cardiopostural control (characterized by baroreflex-mediated muscle-pump effect in response to blood pressure changes, i.e., muscle-pump baroreflex) was assessed using wavelet transform coherence and causality analyses in relation to the baroreflex control of heart rate. Significant cardiopostural blood pressure control was evident counting for almost half of the interaction time with blood pressure changes that observed in the cardiac baroreflex (36.6-72.5% preexercise and 34.7-53.9% postexercise). Thus, cardiopostural input to blood pressure regulation should be considered when investigating orthostatic intolerance. A reduction of both cardiac and muscle-pump baroreflexes in blood pressure regulation was observed postexercise and was likely due to the absence of excessive venous pooling and a less stressed system after mild exercise. With further studies using more effective protocols evoking venous pooling and muscle-pump activity, the cardiopostural interaction could improve our understanding of the autonomic control system and ultimately lead to a more accurate diagnosis of cardiopostural dysfunctions.NEW & NOTEWORTHY We examined the interaction between cardiovascular and postural control systems during standing before and after mild exercise. Significant cardiopostural input to blood pressure regulation was shown, suggesting the importance of cardiopostural integration when investigating orthostatic hypotension. In addition, we observed a reduction of baroreflex-mediated blood pressure regulation after exercise.
Collapse
Affiliation(s)
- Da Xu
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Ajay K Verma
- Department of Electrical Engineering, University of North Dakota, Grand Forks, North Dakota; and
| | - Amanmeet Garg
- Department of Engineering Science, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Michelle Bruner
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Reza Fazel-Rezai
- Department of Electrical Engineering, University of North Dakota, Grand Forks, North Dakota; and
| | - Andrew P Blaber
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia, Canada.,Department of Electrical Engineering, University of North Dakota, Grand Forks, North Dakota; and
| | - Kouhyar Tavakolian
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia, Canada; .,Department of Electrical Engineering, University of North Dakota, Grand Forks, North Dakota; and
| |
Collapse
|
6
|
Influence of sympathetic activity in the control of peripheral microvascular tone in preterm infants. Pediatr Res 2016; 80:793-799. [PMID: 27497044 DOI: 10.1038/pr.2016.160] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 06/21/2016] [Indexed: 01/21/2023]
Abstract
BACKGROUND Microvascular dysregulation following preterm birth is associated with increased illness severity and hypotension, particularly in males. Sympathetic nervous vascular regulation is evident in females. We hypothesized that sympathetic dysfunction in male preterm infants may contribute to a failure of peripheral microvascular vasoconstriction. METHODS Microvascular blood flow of infants 24-43 wk gestational age was assessed at 6, 24, and 72 h of age by laser Doppler. Blood flow Fourier transformed frequency distribution spectra (low frequency/high frequency ratio) were used to assess the influence of sympathetic tone on microvascular regulation. Total sympathetic output was assessed as urinary normetanephrine. RESULTS Microvascular sympathetic activity at 24 h postnatal age decreased in early preterm males, but not females. Peripheral sympathetic activity increased with advancing postnatal age in females, but decreased in males. In early preterm infants, total normetanephrine outputs increase significantly with postnatal age, in both sexes. CONCLUSION Sympathetic activation following preterm birth is sexually dimorphic, with preterm males having reduced sympathetic tone and reduced upregulation of sympathetic tone following birth. There is evidence of a disconnect between central sympathetic activity and local peripheral microcirculatory sympathetic drive. This may relate to autonomic nervous immaturity and highlights the need to understand how preterm birth may affect autonomic function.
Collapse
|
7
|
Borroto-Escuela DO, Pintsuk J, Schäfer T, Friedland K, Ferraro L, Tanganelli S, Liu F, Fuxe K. Multiple D2 heteroreceptor complexes: new targets for treatment of schizophrenia. Ther Adv Psychopharmacol 2016; 6:77-94. [PMID: 27141290 PMCID: PMC4837969 DOI: 10.1177/2045125316637570] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The dopamine (DA) neuron system most relevant for schizophrenia is the meso-limbic-cortical DA system inter alia densely innervating subcortical limbic regions. The field of dopamine D2 receptors and schizophrenia changed markedly with the discovery of many types of D2 heteroreceptor complexes in subcortical limbic areas as well as the dorsal striatum. The results indicate that the D2 is a hub receptor which interacts not only with many other G protein-coupled receptors (GPCRs) including DA isoreceptors but also with ion-channel receptors, receptor tyrosine kinases, scaffolding proteins and DA transporters. Disturbances in several of these D2 heteroreceptor complexes may contribute to the development of schizophrenia through changes in the balance of diverse D2 homo- and heteroreceptor complexes mediating the DA signal, especially to the ventral striato-pallidal γ-aminobutyric acid (GABA) pathway. This will have consequences for the control of this pathway of the glutamate drive to the prefrontal cortex via the mediodorsal thalamic nucleus which can contribute to psychotic processes. Agonist activation of the A2A protomer in the A2A-D2 heteroreceptor complex inhibits D2 Gi/o mediated signaling but increases the D2 β-arrestin2 mediated signaling. Through this allosteric receptor-receptor interaction, the A2A agonist becomes a biased inhibitory modulator of the Gi/o mediated D2 signaling, which may the main mechanism for its atypical antipsychotic properties especially linked to the limbic A2A-D2 heterocomplexes. The DA and glutamate hypotheses of schizophrenia come together in the signal integration in D2-N-methyl-d-aspartate (NMDA) and A2A-D2-metabotropic glutamate receptor 5 (mGlu5) heteroreceptor complexes, especially in the ventral striatum. 5-Hydroxytryptamine 2A (5-HT2A)-D2 heteroreceptor complexes are special targets for atypical antipsychotics with high potency to block their 5-HT2A protomer signaling in view of the potential development of pathological allosteric facilitatory 5-HT2A-D2 interaction increasing D2 protomer signaling. Neurotensin (NTS1)-D2 heterocomplexes also exist in the ventral and dorsal striatum, and likely also in midbrain DA nerve cells as NTS1-D2 autoreceptor complexes where neurotensin produces antipsychotic and propsychotic actions, respectively.
Collapse
Affiliation(s)
- Dasiel O. Borroto-Escuela
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden Department of Biomolecular Science, Section of Physiology, University of Urbino, Italy
| | - Julia Pintsuk
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden Institute of Biomedicine and Translational Medicine, University of Tartu, Estonia
| | - Thorsten Schäfer
- Clinical and Molecular Pharmacy, Department of Chemistry and Pharmacy, Friedrich Alexander University, Erlangen-Nürnberg, Germany
| | - Kristina Friedland
- Clinical and Molecular Pharmacy, Department of Chemistry and Pharmacy, Friedrich Alexander University, Erlangen-Nürnberg, Germany
| | - Luca Ferraro
- Department of Life Sciences and Biotechnology, University of Ferrara, Italy
| | - Sergio Tanganelli
- Department of Life Sciences and Biotechnology, University of Ferrara, Italy Department of Medical Sciences, University of Ferrara, Italy
| | - Fang Liu
- Campbell Research Institute, Centre for Addiction and Mental Health, University of Toronto, Toronto, Ontario, Canada
| | | |
Collapse
|
8
|
Shoemaker JK, Badrov MB, Al-Khazraji BK, Jackson DN. Neural Control of Vascular Function in Skeletal Muscle. Compr Physiol 2015; 6:303-29. [PMID: 26756634 DOI: 10.1002/cphy.c150004] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The sympathetic nervous system represents a fundamental homeostatic system that exerts considerable control over blood pressure and the distribution of blood flow. This process has been referred to as neurovascular control. Overall, the concept of neurovascular control includes the following elements: efferent postganglionic sympathetic nerve activity, neurotransmitter release, and the end organ response. Each of these elements reflects multiple levels of control that, in turn, affect complex patterns of change in vascular contractile state. Primarily, this review discusses several of these control layers that combine to produce the integrative physiology of reflex vascular control observed in skeletal muscle. Beginning with three reflexes that provide somewhat dissimilar vascular patterns of response despite similar changes in efferent sympathetic nerve activity, namely, the baroreflex, chemoreflex, and muscle metaboreflex, the article discusses the anatomical and physiological bases of postganglionic sympathetic discharge patterns and recruitment, neurotransmitter release and management, and details of regional variations of receptor density and responses within the microvascular bed. Challenges are addressed regarding the fundamentals of measurement and how conclusions from one response or vascular segment should not be used as an indication of neurovascular control as a generalized physiological dogma. Whereas the bulk of the article focuses on the vasoconstrictor function of sympathetic neurovascular integration, attention is also given to the issues of sympathetic vasodilation as well as the impact of chronic changes in sympathetic activation and innervation on vascular health. © 2016 American Physiological Society.
Collapse
Affiliation(s)
- J K Shoemaker
- School of Kinesiology, Western University, London, Ontario, Canada.,Department of Physiology and Pharmacology, Western University, London, Ontario, Canada
| | - M B Badrov
- School of Kinesiology, Western University, London, Ontario, Canada
| | - B K Al-Khazraji
- Department of Medical Biophysics, Western University, London, Ontario, Canada
| | - D N Jackson
- Department of Medical Biophysics, Western University, London, Ontario, Canada
| |
Collapse
|
9
|
Are the precapillary sphincters and metarterioles universal components of the microcirculation? An historical review. J Physiol Sci 2013; 63:319-31. [PMID: 23824465 PMCID: PMC3751330 DOI: 10.1007/s12576-013-0274-7] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2013] [Accepted: 06/03/2013] [Indexed: 12/17/2022]
Abstract
The microcirculation is a major topic in current physiology textbooks and is frequently explained with schematics including the precapillary sphincters and metarterioles. We re-evaluated the validity and applicability of the concepts precapillary sphincters and metarterioles by reviewing the historical context in which they were developed in physiology textbooks. The studies by Zweifach up until the 1950s revealed the unique features of the mesenteric microcirculation, illustrated with impressive schematics of the microcirculation with metarterioles and precapillary sphincters. Fulton, Guyton and other authors introduced or mimicked these schematics in their physiology textbooks as representative of the microcirculation in general. However, morphological and physiological studies have revealed that the microcirculation in the other organs and tissues contains no metarterioles or precapillary sphincters. The metarterioles and precapillary sphincters were not universal components of the microcirculation in general, but unique features of the mesenteric microcirculation.
Collapse
|
10
|
Kölegård R, Eiken O. Distensibility in human veins as affected by 5 weeks of repeated elevations of local transmural pressure. Eur J Appl Physiol 2011; 111:3119-25. [DOI: 10.1007/s00421-011-1939-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2010] [Accepted: 03/19/2011] [Indexed: 10/18/2022]
|
11
|
Woods SC, Taborsky GJ, Porte D. Central Nervous System Control of Nutrient Homeostasis. Compr Physiol 2011. [DOI: 10.1002/cphy.cp010407] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
12
|
|
13
|
|
14
|
|
15
|
|
16
|
|
17
|
|
18
|
|
19
|
|
20
|
Karakas A, Turker AU, Gunduz B. Effects of European mistletoe (Viscum albumL. subsp.album) extracts on activity rhythms of the Syrian hamsters (Mesocricetus auratus). Nat Prod Res 2008; 22:990-1000. [DOI: 10.1080/14786410701654776] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
|
21
|
Overview of the Microcirculation. Microcirculation 2008. [DOI: 10.1016/b978-0-12-374530-9.00022-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
|
22
|
Lipp A, Sandroni P, Ahlskog JE, Maraganore DM, Shults CW, Low PA. Calf venous compliance in multiple system atrophy. Am J Physiol Heart Circ Physiol 2007; 293:H260-5. [PMID: 17337590 DOI: 10.1152/ajpheart.01208.2006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In multiple system atrophy (MSA), increased venous compliance with excessive venous pooling is assumed to be a major contributor to orthostatic hypotension (OH); however, venous compliance has never been assessed in MSA patients. We evaluated the severity and distribution of adrenergic, cardiovagal, and sudomotor failure in 11 patients with probable MSA, 14 age- and sex-matched control subjects, and 8 patients with Parkinson's disease (PD) but not OH. Calf venous compliance, venous filling, and capillary filtration were measured using calf plethysmography. The response to the directly acting α-adrenergic stimulation (10 mg midodrine) on calf venous compliance was additionally evaluated. Contrary to our hypothesis, pressure-volume curves in the legs of MSA patients were flatter than in PD patients ( P < 0.05) or controls ( P < 0.001); this indicated reduced calf venous compliance in MSA. The MSA group had reduced venous filling compared with control ( P < 0.001) or PD subjects ( P < 0.001) but had a normal capillary filtration rate ( P = 0.73). Direct α-adrenergic stimulation resulted in a slight but significant reduction of calf venous compliance in controls ( P = 0.001) and PD subjects ( P < 0.001) but not in the MSA group. The compliance change in MSA significantly regressed with autonomic failure (composite autonomic severity scale, r2 = 0.56) but not with parkinsonism (Unified MSA Rating Scale, r2 = 0.12). Our data indicate that MSA patients with chronic OH have reduced, rather than increased, venous compliance in the lower leg. We postulate that chronic venous distension that is associated with OH results in structural remodeling of veins, leading to reduced compliance, a change which may protect patients against orthostatic stress.
Collapse
Affiliation(s)
- A Lipp
- Autonomic Reflex Laboratory, Department of Neurology, Mayo Foundation, 200 First Street SW, Rochester, MN 55905, USA
| | | | | | | | | | | |
Collapse
|
23
|
Lambert GA. Looking in the wrong place? The search for an ideal migraine preventative. Drug Dev Res 2007. [DOI: 10.1002/ddr.20204] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
24
|
Horowski R. A history of dopamine agonists. From the physiology and pharmacology of dopamine to therapies for prolactinomas and Parkinson’s disease – a subjective view. J Neural Transm (Vienna) 2006; 114:127-34. [PMID: 16897593 DOI: 10.1007/s00702-006-0560-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2006] [Accepted: 07/11/2006] [Indexed: 10/24/2022]
|
25
|
|
26
|
Abstract
Serotonin is a major modulator of behavior in vertebrates and invertebrates and deficiencies in the serotonergic system account for several behavioral disorders in humans. The small numbers of serotonergic central neurons of vertebrates and invertebrates produce their effects by use of two modes of secretion: from synaptic terminals, acting locally in "hard wired" circuits, and from extrasynaptic axonal and somatodendritic release sites in the absence of postsynaptic targets, producing paracrine effects. In this paper, we review the evidence of synaptic and extrasynaptic release of serotonin and the mechanisms underlying each secretion mode by combining evidence from vertebrates and invertebrates. Particular emphasis is given to somatic secretion of serotonin by central neurons. Most of the mechanisms of serotonin release have been elucidated in cultured synapses made by Retzius neurons from the central nervous system of the leech. Serotonin release from synaptic terminals occurs from clear and dense core vesicles at active zones upon depolarization. In general, synaptic serotonin release is similar to release of acetylcholine in the neuromuscular junction. The soma of Retzius neurons releases serotonin from clusters of dense core vesicles in the absence of active zones. This type of secretion is dependent of the stimulation frequency, on L-type calcium channel activation and on calcium-induced calcium release. The characteristics of somatic secretion of serotonin in Retzius neurons are similar to those of somatic secretion of dopamine and peptides by other neuron types. In general, somatic secretion by neurons is different from transmitter release from clear vesicles at synapses and similar to secretion by excitable endocrine cells.
Collapse
Affiliation(s)
- Francisco F De-Miguel
- Departamento de Biofísica, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México, 04510 DF, México.
| | | |
Collapse
|
27
|
Ghose S, Fujita M, Morrison P, Uhl G, Murphy DL, Mozley PD, Schou M, Halldin C, Innis R. Specific in vitro binding of (S,S)-[3H]MeNER to norepinephrine transporters. Synapse 2005; 56:100-4. [PMID: 15729740 DOI: 10.1002/syn.20133] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The aim of this study was to determine the selectivity of (S,S)-2-(alpha-(2-methoxyphenoxy)benzyl)morpholine (MeNER) binding to norepinephrine transporters (NET). Quantitative autoradiography studies of NET binding were performed in brains of wildtype mice and those of mutant mice lacking one or two alleles of the NET gene. [3H]MeNER binding in the wildtype mouse brains was consistent with previously reported distributions of NET. Highest levels were found in the locus coeruleus, thalamus, hypothalamus, and bed nucleus of stria terminalis. Specific binding in these regions was approximately 50% in the heterozygous NET mice and negligible in the NET knockout mice. Binding in the wildtype mouse brains was displaced by the NET ligand, nisoxetine, but not by the serotonin or dopamine transporter blockers, citalopram or GBR 12935. [3H]MeNER displayed much higher affinity for NET than for SERT or DAT in homogenate binding studies. Each of these features supports the binding specificity of this candidate in vivo NET ligand.
Collapse
Affiliation(s)
- Subroto Ghose
- Molecular Imaging Branch, NIMH, NIH, Bethesda, Maryland 20892, USA.
| | | | | | | | | | | | | | | | | |
Collapse
|
28
|
Richerson GB. Serotonergic neurons as carbon dioxide sensors that maintain pH homeostasis. Nat Rev Neurosci 2004; 5:449-61. [PMID: 15152195 DOI: 10.1038/nrn1409] [Citation(s) in RCA: 378] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- George B Richerson
- Department of Neurology, Yale University School of Medicine, New Haven, and the Veteran's Affairs Medical Center, West Haven, Connecticut, USA
| |
Collapse
|
29
|
Kushida K, Ishida K, Kikuta J, Kato M, Uchiyama T, Taguchi K. Alpha 2-adrenoceptor modulates the release of acetylcholine from the rostral ventrolateral medulla in response to morphine. Biol Pharm Bull 2004; 26:1548-51. [PMID: 14600399 DOI: 10.1248/bpb.26.1548] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The present study examined the role of the noradrenergic system in the modulation of acetylcholine (ACh) release in the rostral ventrolateral medulla (RVLM) using in vivo microdialysis of morphine. The basal level of ACh was 325.0 +/- 21.1 fmol/20 microl/15 min in the presence of neostigmine (10 microM). Intraperitoneal (i.p.) administration of 5 and 10 mg/kg morphine significantly increased ACh release by the RVLM. This enhancement was reversed by naloxone (1 mg/kg, i.p.). In addition, pretreatment with yohimbine (0.5 mg/kg, i.p.) or prazosin (0.2 mg/kg, i.p.) attenuated the systemic morphine-induced release of ACh in the RVLM. However, propranolol (0.2 mg/kg, i.p.) did not affect the morphine-induced ACh release. The addition of morphine (10(-4) M) to the perfusion medium increased the ACh release by 72.4% of the predrug values. The increased ACh release induced by local application of morphine was attenuated by pretreatment with yohimbine, but not prazosin. These findings suggest that morphine exerts an indirect stimulatory effect on the release of ACh by the RVLM and that the morphine-induced increase in ACh release is modulated by alpha2-adrenoceptors in freely moving rats.
Collapse
Affiliation(s)
- Kazuki Kushida
- Pharmacy Practice and Research Center, Showa Pharmaceutical University, Higashitamagawagakuen, Machida, Tokyo, Japan
| | | | | | | | | | | |
Collapse
|
30
|
Fadel PJ, Keller DM, Watanabe H, Raven PB, Thomas GD. Noninvasive assessment of sympathetic vasoconstriction in human and rodent skeletal muscle using near-infrared spectroscopy and Doppler ultrasound. J Appl Physiol (1985) 2004; 96:1323-30. [PMID: 14657045 DOI: 10.1152/japplphysiol.01041.2003] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The precise role of the sympathetic nervous system in the regulation of skeletal muscle blood flow during exercise has been challenging to define in humans, partly because of the limited techniques available for measuring blood flow in active muscle. Recent studies using near-infrared (NIR) spectroscopy to measure changes in tissue oxygenation have provided an alternative method to evaluate vasomotor responses in exercising muscle, but this approach has not been fully validated. In this study, we tested the hypothesis that sympathetic activation would evoke parallel changes in tissue oxygenation and blood flow in resting and exercising muscle. We simultaneously measured tissue oxygenation with NIR spectroscopy and blood flow with Doppler ultrasound in skeletal muscle of conscious humans ( n = 13) and anesthetized rats ( n = 9). In resting forearm of humans, reflex activation of sympathetic nerves with the use of lower body negative pressure produced graded decreases in tissue oxygenation and blood flow that were highly correlated ( r = 0.80, P < 0.0001). Similarly, in resting hindlimb of rats, electrical stimulation of sympathetic nerves produced graded decreases in tissue oxygenation and blood flow velocity that were highly correlated ( r = 0.93, P < 0.0001). During rhythmic muscle contraction, the decreases in tissue oxygenation and blood flow evoked by sympathetic activation were significantly attenuated ( P < 0.05 vs. rest) but remained highly correlated in both humans ( r = 0.80, P < 0.006) and rats ( r = 0.92, P < 0.0001). These data indicate that, during steady-state metabolic conditions, changes in tissue oxygenation can be used to reliably assess sympathetic vasoconstriction in both resting and exercising skeletal muscle.
Collapse
Affiliation(s)
- Paul J Fadel
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390-8586, USA
| | | | | | | | | |
Collapse
|
31
|
Masuki S, Nose H. Arterial baroreflex control of muscle blood flow at the onset of voluntary locomotion in mice. J Physiol 2003; 553:191-201. [PMID: 12937292 PMCID: PMC2343480 DOI: 10.1113/jphysiol.2003.047530] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
To assess the role of arterial baroreflex control in muscle blood flow (MBF) and voluntary locomotion, mean arterial pressure (MAP), MBF, and electromyograms (EMGs) were measured in freely moving mice before (CNT) and after blocking the afferent or efferent pathway of arterial baroreflexes, carotid sinus denervation (CSD), or intraperitoneal administration of phentolamine (BLK), respectively. MAP was measured through a catheter placed in the femoral artery. MBF was measured with a needle-type laser-Doppler flowmeter and recorded through a low-pass filter with an edge frequency of 0.1 Hz. The frequency and duration of locomotion were judged from EMG recordings in the hindlimb. These probes were implanted at least 2 days before the measurements. Muscle vascular conductance (MVC = MBF/MAP) in all groups started to rise within 1 s after the onset of locomotion, but the increasing rate in CSD and BLK was significantly higher than in CNT for the first 9 s (P < 0.001). MAP in CSD and BLK significantly decreased below the baseline within 1 s and this was highly correlated with the increase in MVC for the first 9 s (R2 = 0.842, P < 0.001), whereas MAP in CNT increased significantly 8 s after the onset of locomotion. Although the total period of movement in a free-moving state for 60 min was not significantly different between CNT and CSD (P > 0.1), the frequency of movement with a short duration of 0.1-0.4 min was higher in CSD than in CNT (P < 0.001), which was highly correlated with the reduction in MAP accompanying each period of movement (R2 = 0.883, P < 0.01). These results suggest that arterial baroreflexes suppress vasodilatation in contracting muscle to maintain MAP at the onset of voluntary locomotion, and are necessary to continue a given duration of locomotion in mice.
Collapse
Affiliation(s)
- Shizue Masuki
- Department of Sports Medical Sciences, Institute on Aging and Adaptation, Shinshu University Graduate School of Medicine, Matsumoto 390-8621, Japan
| | | |
Collapse
|
32
|
Fadel PJ, Zhao W, Thomas GD. Impaired vasomodulation is associated with reduced neuronal nitric oxide synthase in skeletal muscle of ovariectomized rats. J Physiol 2003; 549:243-53. [PMID: 12665606 PMCID: PMC2342919 DOI: 10.1113/jphysiol.2003.038828] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
In exercising skeletal muscle, vasoconstrictor responses to alpha-adrenoceptor activation are attenuated in part by nitric oxide (NO) produced by the neuronal isoform of NO synthase (nNOS), which is expressed constitutively in skeletal muscle cells. In skeletal muscle of pregnant animals, nNOS mRNA is upregulated, suggesting that muscle nNOS expression is modulated by the steroid hormone oestrogen. Whether oestrogen-induced changes in nNOS expression have measurable effects on vasoregulation in skeletal muscle is unknown. In this study, we hypothesized that oestrogen deficiency would reduce muscle nNOS expression, resulting in impaired modulation of sympathetic vasoconstriction in exercising skeletal muscle. Compared to gonadally intact rats, we found that ovariectomized (OVX) rats were characterized by greater sympathetic vasoconstriction in contracting hindlimb and reduced nNOS, but not eNOS, in skeletal muscle. In addition, NOS inhibition resulted in a greater enhancement of sympathetic vasoconstriction in contracting hindlimbs of intact compared to OVX rats. These effects of oestrogen deficiency were prevented by chronic treatment of OVX rats with 17beta-oestradiol, but not with chronic progesterone or acute oestradiol. Further analysis revealed that skeletal muscle nNOS correlated directly with plasma 17beta-oestradiol and inversely with the magnitude of sympathetic vasoconstrictor responses in contracting hindlimbs. These data indicate that NO-dependent attenuation of sympathetic vasoconstriction in contracting skeletal muscle is impaired in oestrogen-deficient female rats, and suggest that this impairment may be mediated by reduced skeletal muscle nNOS expression.
Collapse
Affiliation(s)
- Paul J Fadel
- Department of Internal Medicine, Hypertension Division, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas 75390, USA
| | | | | |
Collapse
|
33
|
Komine H, Matsukawa K, Murata J, Tsuchimochi H, Shimizu K. Forelimb vasodilatation induced by hypothalamic stimulation is greatly mediated with nitric oxide in anesthetized cats. THE JAPANESE JOURNAL OF PHYSIOLOGY 2003; 53:97-103. [PMID: 12877766 DOI: 10.2170/jjphysiol.53.97] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The aim of this study was to examine whether or not stimulation of the hypothalamic defense area is capable of inducing sympathetic vasodilatation of the forelimb vascular bed in anesthetized cats. When the hypothalamic defense area was electrically stimulated, brachial blood flow velocity (brachial BFV) and vascular conductance were increased as well as femoral BFV and vascular conductance. Brachial BFV and vascular conductance increased by 110-139% during hypothalamic stimulation. These increases were blunted to approximately one-fifth of the control responses following i.v. injection of a synthesis inhibitor of nitric oxide, N(omega)-nitro-L-arginine methyl ester (L-NAME). The attenuating effect of L-NAME on forelimb vasodilatation evoked by hypothalamic stimulation was greater than that on hindlimb vasodilatation. The combined administration of L-NAME and atropine sulfate eliminated nearly all of the increases in brachial BFV and vascular conductance during hypothalamic stimulation. From the present results, we conclude that stimulation of the hypothalamic defense area is able to induce neurogenic vasodilatation of the cat forelimb vascular bed, which is greatly mediated with a nitric oxide mechanism. The contribution of nitric oxide to neurogenic vasodilatation seems to be greater in the forelimbs than hindlimbs.
Collapse
Affiliation(s)
- Hidehiko Komine
- Department of Physiology, Institute of Health Sciences, Hiroshima University Faculty of Medicine, Kasumi 1-2-3, Minami-ku, Hiroshima 734-8551, Japan
| | | | | | | | | |
Collapse
|
34
|
Xiang Z, Prince DA. Heterogeneous actions of serotonin on interneurons in rat visual cortex. J Neurophysiol 2003; 89:1278-87. [PMID: 12626611 DOI: 10.1152/jn.00533.2002] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The effects of serotonin (5-HT) on excitability of two cortical interneuronal subtypes, fast-spiking (FS) and low threshold spike (LTS) cells, and on spontaneous inhibitory postsynaptic currents (sIPSCs) in layer V pyramidal cells were studied in rat visual cortical slices using whole-cell recording techniques. Twenty-two of 28 FS and 26 of 35 LTS interneurons responded to local application of 5-HT. In the group of responsive neurons, 5-HT elicited an inward current in 50% of FS cells and 15% of LTS cells, an outward current was evoked in 41% of FS cells and 81% of LTS cells, and an inward current followed by an outward current in 9% of FS cells and 4% LTS cells. The inward and outward currents were blocked by a 5-HT(3) receptor antagonist, tropisetron, and a 5-HT(1A) receptor antagonist, NAN-190, respectively. The 5-HT-induced inward and outward currents were both associated with an increase in membrane conductance. The estimated reversal potential was more positive than -40 mV for the inward current and close to the calculated K(+) equilibrium potential for the outward current. The 5-HT application caused an increase, a decrease, or an increase followed by a decrease in the frequency of sIPSCs in pyramidal cells. The 5-HT(3) receptor agonist 1-(m-chlorophenyl) biguanide increased the frequency of larger and fast-rising sIPSCs, whereas the 5-HT(1A) receptor agonist (+/-)8-hydroxydipropylaminotetralin hydrobromide elicited opposite effects and decreased the frequency of large events. These data indicate that serotonergic activation imposes complex actions on cortical inhibitory networks, which may lead to changes in cortical information processing.
Collapse
Affiliation(s)
- Zixiu Xiang
- Stanford University School of Medicine, Department of Neurology and Neurological Sciences, Stanford, California 94305, USA
| | | |
Collapse
|
35
|
Abstract
The neural control of the subcommissural organ (SCO) has been partially characterized. The best known input is an important serotonergic innervation in the SCO of several mammals. In the rat, this innervation comes from raphe nuclei and appears to exert an inhibitory effect on the SCO activity. A GABAergic innervation has also been shown in the SCO of the rat and frog Rana perezi. In the rat, GABA and the enzyme glutamate decarboxylase are involved in the SCO innervation. GABA is taken up by some secretory ependymocytes and nerve terminals, coexisting with serotonin in a population of synaptic terminals. Dopamine, noradrenaline, and different neuropeptides such as LH-RH, vasopressin, vasotocin, oxytocin, mesotocin, substance P, alpha-neoendorphin, and galanin are also involved in SCO innervation. In the bovine SCO, an important number of fibers containing tyrosine hydroxylase are present, indicating that in this species dopamine and/or noradrenaline-containing fibers are an important neural input. In Rana perezi, a GABAergic innervation of pineal origin could explain the influence of light on the SCO secretory activity in frogs. A general conclusion is that the SCO cells receive neural inputs from different neurotransmitter systems. In addition, the possibility that neurotransmitters and neuropeptides present in the cerebrospinal fluid may also affect the SCO activity, is discussed.
Collapse
Affiliation(s)
- A J Jiménez
- Departamento de Biología Celular y Genética, Facultad de Ciencias, Universidad de Málaga, Málaga, Spain.
| | | | | |
Collapse
|
36
|
Abstract
Epidural anaesthesia has been used since the early 1900s. Consequently the general characteristics of these procedures have been well defined. More studies have provided a better understanding of the cardiopulmonary changes produced by epidural anaesthesia. The cardiovascular effects observed with epidural anaesthesia are complex and variable, depending on a multitude of factors. The extent of sympathetic denervation, balance of sympathetic and parasympathetic activity, the pharmacological effect of systemically absorbed local anaesthetic agents, inclusion of adrenaline in the anaesthetic solution, the distribution of blood in relation to cardiac filling and cardiovascular function of the patient must be taken into account when considering the circulatory effects of epidural anaesthesia. Individual cardiovascular response to different levels of sympathetic blockade varies widely, depending on the degree of sympathetic tone before the block. Epidural anaesthesia that is restricted to the level of the low thoracic and lumbar region (T5-L4) results in a "peripheral" sympathetic blockade with vascular dilatation in the pelvis and lower limbs. High thoracic epidural anaesthesia, from the first to fifth thoracic, blocks the cardiac afferent and efferent sympathetic fibres with loss of chronotropic and inotropic drive to the myocardium. Thoracic epidural anaesthesia appears to at least partly reverse the diaphragmatic dysfunction that is a major determinant of the decrease in lung volumes observed after upper abdominal surgery. This article summarizes cardiovascular and pulmonary responses to epidural anaesthesia. Details of clinical management are not included in the review.
Collapse
Affiliation(s)
- B T Veering
- Department of Anesthesiology, Leiden University Medical Center, Leiden, The Netherlands
| | | |
Collapse
|
37
|
Hsieh NK, Liu JC, Chen HI. Localization of sympathetic postganglionic neurons innervating mesenteric artery and vein in rats. JOURNAL OF THE AUTONOMIC NERVOUS SYSTEM 2000; 80:1-7. [PMID: 10742533 DOI: 10.1016/s0165-1838(99)00070-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
Physiological and histochemical studies have demonstrated the control and innervation of sympathetic nerves to the artery and vein vessels of splanchnic circulation. In our laboratory, we first used the technique of retrograde transport of horseradish peroxidase to identify the origin of sympathetic neurons innervating the mesenteric vein. In this study, double fluorescence staining technique was used for a simultaneous localization of the sympathetic postganglionic neurons supplying the mesenteric artery and vein in rats. First-order branches of mesenteric artery (A) and vein (V) in the vicinity of ileo-cecal junction were isolated for application of fluorescent dyes (Fast Blue, FB and Diamidino Yellow, DY). The application of FB and DY on A and V was alternated in the next animal to minimize the difference in dye uptake. The animal was allowed to recover for 6-7 days assuring a complete uptake of FB and DY into the cytoplasm and nucleus, respectively. The number of FB, DY and double staining neurons in the prevertebral and paravertebral ganglia were counted under a fluorescent microscope after animal fixation and serial frozen section (30 microm) of the sympathetic ganglia. Our study revealed the following findings: (1) Distribution of the fluorescence-staining neurons in the sympathetic ganglia was as follows: right celiac ganglion (39%), superior mesenteric ganglion (30%), left celiac ganglion (26%), inferior mesenteric ganglion (1%) and paravertebral ganglia (4%). (2) Double staining neurons that dually innervate A and V amounted to 54% of total staining neurons. There were 41% neurons singly innervating A and 5% innervating V. (3) The ratio of neurons supplying the A and V ranged from 1.41 to 1.75 (average 1.61). (4) There was no distinct topographical distribution with respect to the neuron location innervating A and V. The distribution of neurons appeared in a scattering pattern.
Collapse
Affiliation(s)
- N K Hsieh
- Institute of Medical Science and Department of Physiology, Tzu Chi College of Medicine and Humanities, Hualien, Taiwan
| | | | | |
Collapse
|
38
|
Abstract
Movement, the fundamental component of behavior and the principal extrinsic action of the brain, is produced when skeletal muscles contract and relax in response to patterns of action potentials generated by motoneurons. The processes that determine the firing behavior of motoneurons are therefore important in understanding the transformation of neural activity to motor behavior. Here, we review recent studies on the control of motoneuronal excitability, focusing on synaptic and cellular properties. We first present a background description of motoneurons: their development, anatomical organization, and membrane properties, both passive and active. We then describe the general anatomical organization of synaptic input to motoneurons, followed by a description of the major transmitter systems that affect motoneuronal excitability, including ligands, receptor distribution, pre- and postsynaptic actions, signal transduction, and functional role. Glutamate is the main excitatory, and GABA and glycine are the main inhibitory transmitters acting through ionotropic receptors. These amino acids signal the principal motor commands from peripheral, spinal, and supraspinal structures. Amines, such as serotonin and norepinephrine, and neuropeptides, as well as the glutamate and GABA acting at metabotropic receptors, modulate motoneuronal excitability through pre- and postsynaptic actions. Acting principally via second messenger systems, their actions converge on common effectors, e.g., leak K(+) current, cationic inward current, hyperpolarization-activated inward current, Ca(2+) channels, or presynaptic release processes. Together, these numerous inputs mediate and modify incoming motor commands, ultimately generating the coordinated firing patterns that underlie muscle contractions during motor behavior.
Collapse
Affiliation(s)
- J C Rekling
- Department of Neurobiology, University of California, Los Angeles, California 90095-1763, USA
| | | | | | | | | |
Collapse
|
39
|
Byrd KE, Yang L, Yancey KW, Teomim D, Domb AJ. Increased in vivo levels of neurotransmitters to trigeminal motoneurons: effects on craniofacial bone and TMJ. THE ANATOMICAL RECORD 2000; 258:369-83. [PMID: 10737855 DOI: 10.1002/(sici)1097-0185(20000401)258:4<369::aid-ar5>3.0.co;2-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The results of chronic, in vivo delivery of excitatory and inhibitory neurotransmitter substances upon the craniofacial skeleton are of ongoing interest to clinician and basic scientist alike. Our purpose was to document and compare the effects of biodegradable glycine, glutamate, and thyrotropin-releasing hormone (TRH) microspheres upon the craniofacial skeleton and TMJ of actively growing rats. Glycine, glutamate, TRH, and blank microspheres were stereotactically implanted in proximity to motoneurons within the trigeminal motor nucleus in order to test the following null hypotheses: (1) neurotransmitter microspheres implanted near trigeminal motoneurons of growing rats have no significant effect on the craniofacial skeleton and temporomandibular joints of implanted animals, and (2) there are no significant differences between the relative effects of glutamate, TRH (excitatory to trigeminal motoneurons), and glycine (inhibitory to trigeminal motoneurons) implants upon the craniofacial skeleton and temporomandibular joint. Fifty male Sprague-Dawley rats underwent stereotactic neurosurgery at 35 days; five rats each were killed at 14 and 21 days postoperative for data collection and comparison between glycine-, glutamate-, TRH-, blank-microsphere, and sham-surgery rats. Glycine rats had significantly (P < or = 0.05, 0. 01) smaller implant-side cranial dimensions and mandibular condyles, all glycine rats showed increased gracility of implant-side bones, and deviation of their facial skeleton away from the implant-side; this was in contrast to the generally larger implant-side bony structures in both glutamate and TRH rats. The two null hypotheses were both rejected. Due to their inhibitory and excitatory effects upon trigeminal motoneurons, masticatory muscles, and their neuromuscular generation of biomechanical forces that affect bone, the neurotransmitter substances glycine, glutamate, and TRH appear to play an important role in the growth and development of the mammalian craniofacial skeleton and TMJ.
Collapse
Affiliation(s)
- K E Byrd
- Department of Anatomy, Indiana University School of Medicine, Indianapolis 46202, USA.
| | | | | | | | | |
Collapse
|
40
|
Smit AA, Halliwill JR, Low PA, Wieling W. Pathophysiological basis of orthostatic hypotension in autonomic failure. J Physiol 1999; 519 Pt 1:1-10. [PMID: 10432334 PMCID: PMC2269496 DOI: 10.1111/j.1469-7793.1999.0001o.x] [Citation(s) in RCA: 225] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/1998] [Accepted: 06/16/1999] [Indexed: 11/30/2022] Open
Abstract
In patients with autonomic failure orthostatic hypotension results from an impaired capacity to increase vascular resistance during standing. This fundamental defect leads to increased downward pooling of venous blood and a consequent reduction in stroke volume and cardiac output that exaggerates the orthostatic fall in blood pressure. The location of excessive venous blood pooling has not been established so far, but present data suggest that the abdominal compartment and perhaps leg skin vasculature are the most likely candidates. To improve the orthostatic tolerance in patients with autonomic failure, protective measures that reduce excessive orthostatic blood pooling have been developed and evaluated. These measures include physical counter-manoeuvres and abdominal compression.
Collapse
Affiliation(s)
- A A Smit
- Department of Internal Medicine, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands
| | | | | | | |
Collapse
|
41
|
Shoemaker JK, McQuillan PM, Sinoway LI. Upright posture reduces forearm blood flow early in exercise. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 276:R1434-42. [PMID: 10233037 DOI: 10.1152/ajpregu.1999.276.5.r1434] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The hypothesis that upright posture could modulate forearm blood flow (FBF) early in exercise was tested in six subjects. Both single (2-s duration) and repeated (1-s work/2-s rest cadence for 12 contractions) handgrip contractions (12 kg) were performed in the supine and 70 degrees head-up tilt (HUT) positions. The arm was maintained at heart level to diminish myogenic effects. Baseline brachial artery diameters were assessed at rest in each position. Brachial artery mean blood velocity (MBV; Doppler) and mean arterial pressure (MAP) (Finapres) were measured continuously to calculate FBF and vascular conductance. MAP was not changed with posture. Antecubital venous pressure (Pv) was reduced in HUT (4.55 +/- 1.3 mmHg) compared with supine (11.3 +/- 1.9 mmHg) (P < 0.01). For the repeated contractions, total excess FBF (TEF) was reduced in the HUT position compared with supine (P < 0.02). With the single contractions, peak FBF, peak vascular conductance, and TEF during 30 s after release of the contraction were reduced in the HUT position compared with supine (P < 0.01). Sympathetic blockade augmented the FBF response to a single contraction in HUT (P < 0.05) and tended to increase this response while supine (P = 0.08). However, sympathetic blockade did not attenuate the effect of HUT on peak FBF and TEF after the single contractions. Raising the arm above heart level while supine, to diminish Pv, resulted in FBF dynamics that were similar to those observed during HUT. Alternatively, lowering the arm while in HUT to restore Pv to supine levels restored the peak FBF and vascular conductance responses, but not TEF response, after a single contraction. It was concluded that upright posture diminishes the hyperemic response early in exercise. The data demonstrate that sympathetic constriction restrains the hyperemic response to a single contraction but does not modulate the postural reduction in postcontraction hyperemia. Therefore, the attenuated blood flow response in the HUT posture was largely related to factors associated with diminished venous pressures and not sympathetic vasoconstriction.
Collapse
Affiliation(s)
- J K Shoemaker
- Section of Cardiology, The Pennsylvania State University College of Medicine, The Milton S. Hershey Medical Center, Hershey, Pennsylvania 17033, USA.
| | | | | |
Collapse
|
42
|
Johnson CD, Gilbey MP. Focally recorded single sympathetic postganglionic neuronal activity supplying rat lateral tail vein. J Physiol 1998; 508 ( Pt 2):575-85. [PMID: 9508818 PMCID: PMC2230877 DOI: 10.1111/j.1469-7793.1998.575bq.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
1. In anaesthetized rats, using a focal recording technique, activity was recorded from single sympathetic postganglionic neurones innervating the lateral tail veins. On-going activity was examined in order to determine whether it had similar or different characteristics to those recorded from the caudal ventral artery in a previous study. 2. Animals were artificially ventilated, vagotomized, paralysed and given a pneumothorax. 3. The discharges of fourteen out of seventeen sympathetic postganglionic neurones were rhythmic. Such units had a mean firing frequency of 1.62 +/- 0. 70 Hz. The mean frequency of the dominant sympathetic rhythm under control conditions was 0.82 +/- 0.05 Hz. 4. The frequency of the dominant sympathetic rhythm was different from that of the phrenic rhythm in nine out of fourteen cases. 5. The mean frequency of the dominant sympathetic rhythm was: (i) not influenced significantly by hypocapnic apnoea, (ii) decreased by hyperthermia, which increased the frequency of the phrenic rhythm, (iii) in all cases different from that of the artificial ventilation cycle. 6. The above characteristics are similar to those recorded from the sympathetic supply to the caudal ventral artery of the same vascular bed under comparable conditions.
Collapse
Affiliation(s)
- C D Johnson
- Autonomic Neuroscience Institute, Department of Physiology, Royal Free Hospital School of Medicine, Rowland Hill Street, London NW3 2PF, UK
| | | |
Collapse
|
43
|
Abstract
The subcommissural organ (SCO) is a phylogenetically ancient and conserved structure. During ontogeny, it is one of the first brain structures to differentiate. In many species, including the human, it reaches its full development during embryonic life. The SCO is a glandular structure formed by ependymal and hypendymal cells highly specialized in the secretion of proteins. It is located at the entrance of the aqueduct of Sylvius. The ependymal cells secrete into the ventricle core-glycosylated proteins of high molecular mass. The bulk of this secretion is formed by glycoproteins that would derive from two different precursors of 540 and 320 kDa and that, upon release into the ventricle aggregate, form a threadlike structure known as Reissner's fiber (RF). By addition of newly released glycoproteins to its proximal end, RF grows caudally and extends along the aqueduct, fourth ventricle, and the whole length of the central canal of the spinal cord. RF material continuously arrives at the dilated caudal end of the central canal, known as the terminal ventricle or ampulla. When reaching the ampulla, the RF material undergoes chemical modifications, disaggregates, and then escapes through openings in the dorsal wall of the ampulla to finally reach local blood vessels. The SCO also appears to secrete a cerebrospinal fluid (CSF)-soluble material that is different from the RF material that circulates in the ventricular and subarachnoidal CSF. Cell processes of the ependymal and hypendymal cells, containing a secretory material, terminate at the subarachnoidal space and on the very special blood capillaries supplying the SCO. The SCO is sequestered within a double-barrier system, a blood-brain barrier, and a CSF-SCO barrier. The function of the SCO is unknown. Some evidence suggests that the SCO may participate in different processes such as the clearance of certain compounds from the CSF, the circulation of CSF, and morphogenetic mechanisms.
Collapse
Affiliation(s)
- E M Rodríguez
- Instituto de Histología y Patología, Facultad de Medicina, Universidad Austral de Chile, Valdivia
| | | | | |
Collapse
|
44
|
Xu ZQ, Shi TJ, Hökfelt T. Galanin/GMAP- and NPY-like immunoreactivities in locus coeruleus and noradrenergic nerve terminals in the hippocampal formation and cortex with notes on the galanin-R1 and -R2 receptors. J Comp Neurol 1998; 392:227-51. [PMID: 9512271 DOI: 10.1002/(sici)1096-9861(19980309)392:2<227::aid-cne6>3.0.co;2-4] [Citation(s) in RCA: 139] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
By using immunofluorescence methodology, extensive galanin (GAL) and GAL message-associated peptide (GMAP)-positive terminal networks were observed in the hippocampal formation. The majority of the GAL/GMAP fibers were dopamine beta-hydroxylase- (DBH) positive, that is, they were noradrenergic. This finding was established with GAL/GMAP-DBH double-staining and with 6-hydroxy-dopamine treatment, which totally abolished all fibers in which GAL/GMAP and DBH coexisted. Also, reserpine treatment caused a marked depletion of GAL. No evidence for GAL/GMAP coexistence with 5-hydroxytryptamine was obtained. In the ventral hippocampus, GAL/GMAP-, DBH-negative fibers were seen in the stratum oriens, the anterior stratum radiatum, along the granule cell layer and in the strata oriens and alveus. In the locus coeruleus (LC), around 80% of the GMAP-positive neurons contained neuropeptide tyrosine (NPY), and about 40% of the NPY-positive neurons expressed GMAP. GAL-R1 receptor mRNA was expressed in Barrington's nucleus (close to the LC), but was not detected in the hippocampal formation/dorsal cortical areas. GAL-R2 receptor mRNA was found in the granule cell layer in the dentate gyrus. The present results show that most, but not all, immunohistochemically detectable GAL/GMAP in the hippocampal formation/dorsal cortex is present in noradrenergic nerve terminals originating in the LC, which has a robust GAL/GMAP synthesis. The functional role of GAL may be related to noradrenaline, possibly by a presynaptic action. However, the presence of GAL in other systems and of GAL-R2 receptor mRNA in granule cells also indicates other targets.
Collapse
Affiliation(s)
- Z Q Xu
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | | | | |
Collapse
|
45
|
Byrd KE, Sukay MJ, Dieterle MW, Yang L, Marting TC, Teomim D, Domb AJ. Craniofacial and TMJ effects after glutamate and TRH microsphere implantation in proximity to trigeminal motoneurons of growing rats. J Dent Res 1997; 76:1437-52. [PMID: 9240380 DOI: 10.1177/00220345970760080601] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The sequelae of sustained, in vivo delivery of two important neurotransmitter substances, glutamate and thyrotropin-releasing hormone (TRH), upon craniofacial growth and development have previously not been investigated. Our purpose was to document and compare the relative effects of glutamate and TRH microspheres stereotactically placed in proximity to trigeminal motoneurons within the trigeminal motor nucleus. The following null hypotheses were tested: (1) TRH microspheres in proximity to trigeminal motoneurons have no significant effect upon the craniofacial skeleton, and (2) there are no significant differences between the relative effects of chronic, long-term delivery of glutamate and TRH upon the neuromusculoskeletal system of growing rats. Forty male Sprague-Dawley rats were divided into 4 experimental groups (glutamate microspheres, TRH microspheres, blank microspheres, sham surgeries) and underwent stereotactic neurosurgery at 35 days; 5 rats of each group were killed at 14 and 21 days for data collection. Histology revealed that implants were clustered in the pontine reticular formation, close to the ventrolateral tegmental nucleus. Both glutamate and TRH rats had implant-side deviation of their facial skeleton and snout regions; 4 x 2 ANOVA and post hoc t-tests revealed significant (P < or = 0.05, 0.01) differences between groups and sides for motoneuron count, muscle weight, and osteometric data. TRH rats also demonstrated larger implant-side TMJ discs and mandibular fossae in comparison with the other groups. The stated null hypotheses were therefore rejected.
Collapse
Affiliation(s)
- K E Byrd
- Department of Anatomy, Indiana University School of Medicine, Indianapolis 46202-5120, USA
| | | | | | | | | | | | | |
Collapse
|
46
|
Bjarkam CR, S�rensen JC, Geneser FA. Distribution and morphology of serotonin-immunoreactive neurons in the brainstem of the New Zealand white rabbit. J Comp Neurol 1997. [DOI: 10.1002/(sici)1096-9861(19970421)380:4<507::aid-cne7>3.0.co;2-5] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
47
|
Matsukawa K, Shindo T, Shirai M, Ninomiya I. Direct observations of sympathetic cholinergic vasodilatation of skeletal muscle small arteries in the cat. J Physiol 1997; 500 ( Pt 1):213-25. [PMID: 9097945 PMCID: PMC1159371 DOI: 10.1113/jphysiol.1997.sp022011] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
1. The aim of this study was to examine the actual changes of the internal diameter (i.d.) of arterial vessels of skeletal muscle evoked by activation of sympathetic cholinergic nerve fibres during stimulation of the hypothalamic defence area in anaesthetized cats. 2. For this purpose, we have used our novel X-ray TV system for visualizing small arteries (100-500 microm i.d.) of the triceps surae muscle and larger extramuscular arteries (500-1400 microm i.d.) of the hindlimb (the femoral (FA), popliteal (PA) and distal caudal femoral (DCFA) arteries). The passage of a contrast medium from the large extramuscular arteries to the smaller intramuscular arteries was serially measured before and during hypothalamic stimulation. 3. Hypothalamic stimulation increased mean arterial blood pressure, heart rate and femoral vascular conductance. The i.d. of FA, PA, and DCFA did not change during the hypothalamic stimulation, whereas the i.d. of small arteries in the triceps surae muscle increased by 48 +/- 2% (mean +/- S.E.M.) and the cross-sectional area increased concomitantly by 118%. The maximum increase in i.d. of 78 +/- 6%, was observed in arteries of 100-200 microm. These increases in diameter were markedly reduced by intra-arterial injection of atropine or by cutting the sciatic nerve, but not by phentolamine and propranolol given together. 4. The vasodilatation evoked by hypothalamic stimulation was seen in almost all the sections of the small arteries observed under control conditions and was distributed along the entire length of the vessel. In addition, the number of arterial vessels that could be detected increased by 42% during hypothalamic stimulation. The newly detected arterial branches, which ranged from 100 to 300 microm in diameter, mostly arose from the branching points. 5. It is concluded that stimulation of sympathetic cholinergic nerve fibres dilates the small arteries of skeletal muscle ranging from 100 to 500 microm, but not the larger extramuscular arteries.
Collapse
Affiliation(s)
- K Matsukawa
- Department of Cardiac Physiology, National Cardiovascular Centre Research Institute, Suita, Osaka, Japan
| | | | | | | |
Collapse
|
48
|
Leshin LS, Kraeling RR, Kineman RD, Barb CR, Rampacek GB. Immunocytochemical distribution of catecholamine-synthesizing neurons in the hypothalamus and pituitary gland of pigs: tyrosine hydroxylase and dopamine-beta-hydroxylase. J Comp Neurol 1996; 364:151-68. [PMID: 8789282 DOI: 10.1002/(sici)1096-9861(19960101)364:1<151::aid-cne12>3.0.co;2-1] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
This study describes the distribution of catecholaminergic neurons in the hypothalamus and the pituitary gland of the domestic pig, Sus scrofa, an animal that is widely used as an experimental model of human physiology in addition to its worldwide agricultural importance. Hypothalamic catecholamine neurons were identified by immunocytochemical staining for the presence of the catecholamine synthesizing enzymes, tyrosine hydroxylase and dopamine-beta-hydroxylase. Tyrosine hydroxylase-immunoreactive perikarya were observed in the periventricular region throughout the extent of the third ventricle, the anterior and retrochiasmatic divisions of the supraoptic nucleus, the suprachiasmatic nucleus, the ventral and dorsolateral regions of the paraventricular nucleus and adjacent dorsal hypothalamus, the ventrolateral arcuate nucleus, and the posterior hypothalamus. Perikarya ranged from parvicellular (10-15 microns) to magnocellular (25-50 microns) and were of multiple shapes (rounded, fusiform, triangular, or multipolar) and generally had two to five processes with branched arborization. No dopamine-beta-hydroxylase immunoreactive perikarya were observed within the hypothalamus or in the adjacent basal forebrain structures. Both tyrosine hydroxylase- and dopamine-beta-hydroxylase-immunoreactive fibers and punctate varicosities were observed throughout areas containing tyrosine hydroxylase perikarya, but dopamine-beta-hydroxylase immunoreactivity was very sparse within the median eminence. Within the pituitary gland, only tyrosine hydroxylase fibers, and not dopamine-beta-hydroxylase immunoreactive fibers, were located throughout the neurohypophyseal tract and within the posterior pituitary in both pars intermedia and pars nervosa regions. Generally, the location and patterns of both catecholamine-synthesizing enzymes were similar to those reported for other mammalian species except for the absence of the A15 dorsal group and the very sparse dopamine-beta-hydroxylase immunoreactive fibers and varicosities in the median eminence in the pig. These findings provide an initial framework for elucidating behavioral and neuroendocrine species differences with regard to catecholamine neurotransmitters.
Collapse
Affiliation(s)
- L S Leshin
- USDA-ARS, R.B. Russell Agricultural Research Center, Athens, Georgia 30604, USA
| | | | | | | | | |
Collapse
|
49
|
Karim F. Neuroendocrine regulation of vascular capacitance. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1995; 381:81-94. [PMID: 8867826 DOI: 10.1007/978-1-4615-1895-2_9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- F Karim
- Department of Physiology, Leeds University, United Kingdom
| |
Collapse
|
50
|
Häbler HJ, Jänig W, Michaelis M. Respiratory modulation in the activity of sympathetic neurones. Prog Neurobiol 1994; 43:567-606. [PMID: 7816936 DOI: 10.1016/0301-0082(94)90053-1] [Citation(s) in RCA: 111] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- H J Häbler
- Physiologisches Institut, Christian-Albrechts-Universität zu Kiel, Germany
| | | | | |
Collapse
|