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Vasoactive Intestinal Polypeptide in the Carotid Body-A History of Forty Years of Research. A Mini Review. Int J Mol Sci 2020; 21:ijms21134692. [PMID: 32630153 PMCID: PMC7370131 DOI: 10.3390/ijms21134692] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 06/29/2020] [Accepted: 06/30/2020] [Indexed: 12/18/2022] Open
Abstract
Vasoactive intestinal polypeptide (VIP) consists of 28 amino acid residues and is widespread in many internal organs and systems. Its presence has also been found in the nervous structures supplying the carotid body not only in mammals but also in birds and amphibians. The number and distribution of VIP in the carotid body clearly depends on the animal species studied; however, among all the species, this neuropeptide is present in nerve fibers around blood vessels and between glomus cell clusters. It is also known that the number of nerves containing VIP located in the carotid body may change under various pathological and physiological factors. The knowledge concerning the functioning of VIP in the carotid body is relatively limited. It is known that VIP may impact the glomus type I cells, causing changes in their spontaneous discharge, but the main impact of VIP on the carotid body is probably connected with the vasodilatory effects of this peptide and its influence on blood flow and oxygen delivery. This review is a concise summary of forty years of research concerning the distribution of VIP in the carotid body.
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Abstract
The discovery of the sensory nature of the carotid body dates back to the beginning of the 20th century. Following these seminal discoveries, research into carotid body mechanisms moved forward progressively through the 20th century, with many descriptions of the ultrastructure of the organ and stimulus-response measurements at the level of the whole organ. The later part of 20th century witnessed the first descriptions of the cellular responses and electrophysiology of isolated and cultured type I and type II cells, and there now exist a number of testable hypotheses of chemotransduction. The goal of this article is to provide a comprehensive review of current concepts on sensory transduction and transmission of the hypoxic stimulus at the carotid body with an emphasis on integrating cellular mechanisms with the whole organ responses and highlighting the gaps or discrepancies in our knowledge. It is increasingly evident that in addition to hypoxia, the carotid body responds to a wide variety of blood-borne stimuli, including reduced glucose and immune-related cytokines and we therefore also consider the evidence for a polymodal function of the carotid body and its implications. It is clear that the sensory function of the carotid body exhibits considerable plasticity in response to the chronic perturbations in environmental O2 that is associated with many physiological and pathological conditions. The mechanisms and consequences of carotid body plasticity in health and disease are discussed in the final sections of this article.
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Affiliation(s)
- Prem Kumar
- School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, The University of Birmingham, Birmingham, United Kingdom.
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Fidone SJ, Gonzalez C. Initiation and Control of Chemoreceptor Activity in the Carotid Body. Compr Physiol 2011. [DOI: 10.1002/cphy.cp030209] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Campanucci VA, Nurse CA. Autonomic innervation of the carotid body: role in efferent inhibition. Respir Physiol Neurobiol 2007; 157:83-92. [PMID: 17353154 DOI: 10.1016/j.resp.2007.01.020] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2006] [Revised: 01/20/2007] [Accepted: 01/22/2007] [Indexed: 10/23/2022]
Abstract
The carotid body (CB) is a chemosensory organ that monitors blood chemicals and initiates compensatory reflex adjustments to maintain homeostasis. The 'afferent' sensory discharge induced by changes in blood chemicals, e.g. low PO(2) (hypoxia), is relayed by carotid sinus nerve (CSN) fibers and has been well studied. Much less is known, however, about a parallel autonomic (parasympathetic) 'efferent' pathway that is the source of CB inhibition. This pathway is the focus of this review which begins with a historical account of the early findings and links them to more recent data on the source of this innervation, and the role of endogenous neurotransmitters in efferent inhibition. We review evidence that these autonomic neurons are embedded in 'paraganglia' within the glossopharyngeal (GPN) and CSN nerves, and for the role of nitric oxide (NO) in mediating efferent inhibition. Finally, we discuss recent data linking the action of hypoxia and a key CB neurotransmitter, i.e. ATP, to potential mechanisms for activating this efferent pathway.
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Satoda T, Takahashi O, Uchida T, Mizuno N. An anterograde-retrograde labeling study of the carotid sinus nerve of the Japanese monkey (Macaca fuscata). Neurosci Res 1995; 22:381-7. [PMID: 7478303 DOI: 10.1016/0168-0102(95)00918-j] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The sites of origin and termination of efferent and afferent fibers in the carotid sinus nerve (CSN) were investigated in the Japanese monkey. After application of a mixture of horseradish peroxidase (HRP) and wheat germ aggulutinin-conjugated HRP to the central cut end of the CSN, sensory ganglion neurons were labeled in the jugular ganglion of the vagus nerve, as well as in the superior and petrosal ganglia of the glossopharyngeal nerve. Many sympathetic ganglion neurons were also labeled retrogradely in the superior cervical ganglion. In the brain, many labeled terminals were seen ipsilaterally in the lateral division of the nucleus of the solitary tract (NST). A few neuronal cell bodies were also labeled ipsilaterally in a reticular region dorsomedial to the caudal one-third of the facial nucleus. The results indicate that the CSN of the Japanese monkey is composed mainly of afferent fibers terminating in the NST, that the afferent fibers in the CSN originate not only from the superior and petrosal ganglia of the glossopharyngeal nerve but also from the jugular ganglion of the vagus nerve, and that efferent fibers contained in the CSN arise from the medullary reticular formation and superior cervical ganglion.
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Affiliation(s)
- T Satoda
- Department of Oral Anatomy (2nd division), School of Dentistry, Hiroshima University, Japan
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Wang ZZ, Stensaas LJ, Dinger BG, Fidone SJ. Nitric oxide mediates chemoreceptor inhibition in the cat carotid body. Neuroscience 1995; 65:217-29. [PMID: 7753397 DOI: 10.1016/0306-4522(94)00437-a] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Numerous studies have demonstrated that carotid sinus nerve fibers mediate a so-called "efferent" inhibition of carotid body chemoreceptors. However, the mechanism(s) underlying this phenomenon are not understood. Recently, it has been shown that an extensive plexus of nitric oxide synthase-containing carotid sinus nerve fibers innervate the carotid body, and that many fine, beaded fibers can be seen in close proximity to small blood vessels as well as lobules of parenchymal cells. The present study examined the effects of centrifugal neural activity in the carotid sinus nerve on the accumulation of [3H]citrulline synthesized from [3H]arginine in the cat carotid body, and the possible involvement of nitric oxide in mediating "efferent" chemoreceptor inhibition. Electrical stimulation of carotid sinus nerve C-fibers evoked an increase in [3H]citrulline accumulation in the carotid body, which was Ca(2+)-dependent and blocked by L-NG-nitroarginine methylester (0.1 mM), an inhibitor of nitric oxide synthase. Using a vascularly perfused in vitro carotid body preparation, chemoreceptor activity was recorded from thin nerve filaments split-off from the main trunk of the carotid sinus nerve. Electrical stimulation of the main nerve trunk at C-fiber intensities inhibited steady-state chemoreceptor discharge, and this effect was blocked by L-NG-nitroarginine methylester. However, when the organ preparation was switched to the superfuse-only mode, carotid sinus nerve stimulation failed to alter the steady-state discharge, but under these conditions, prolonged nerve stimulation (> 5 min) did attenuate the chemoreceptor response to hypoxia, an effect which was likewise blocked by L-NG-nitroarginine methylester. The present data, together with previous anatomical findings that nitric oxide synthase immunoreactivity is present in both sensory and autonomic ganglion cells innervating the carotid body, suggest that two neural mechanisms may be involved in the inhibitory neural regulation of carotid chemoreceptors. One mechanism appears to involve nitric oxide release from intralobular sensory C-fibers, which lie in close proximity to the chemoreceptor type I cells. The other mechanism involves release of nitric oxide from perivascular terminals of autonomic microganglia neurons, which control carotid body blood flow.
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Affiliation(s)
- Z Z Wang
- Department of Physiology, University of Utah School of Medicine, Salt Lake City 84108, USA
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Kummer W, Gibbins IL, Stefan P, Kapoor V. Catecholamines and catecholamine-synthesizing enzymes in guinea-pig sensory ganglia. Cell Tissue Res 1990; 261:595-606. [PMID: 1978803 DOI: 10.1007/bf00313540] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Cranial and spinal sensory ganglia of the guinea-pig were investigated by means of histochemistry and biochemistry for the presence of catecholamines and catecholamine-synthesizing enzymes. Sensory neurons exhibiting immunoreactivity to the rate-limiting enzyme of catecholamine synthesis, tyrosine hydroxylase (TH), were detected by immunohistochemistry in lumbo-sacral dorsal root ganglia, the nodose ganglion and the petrosal/jugular ganglion complex. The carotid body was identified as a target of TH-like-immunoreactive (TH-LI) neurons by the use of combined retrograde tracing and immunohistochemistry. Double-labelling immunofluorescence revealed that most TH-LI neurons also contained somatostatin-LI, but TH-LI did not coexist with either calcitonin gene-related peptide- or substance P-LI. TH-LI neurons did not react with antibodies to other enzymes involved in catecholamine synthesis, i.e., aromatic amino acid decarboxylase (AADC), dopamine-beta-hydroxylase (D beta H), and phenylethanolamine-N-methyl-transferase (PNMT). Petrosal neurons as well as their endings in the carotid body lacked dopamine- and L-DOPA-LI. Sensory neurons did not display glyoxylic acid-induced catecholamine fluorescence. Ganglia containing TH-LI neurons were kept in short-term organ culture after crushing their roots and the exiting nerve in order to enrich intra-axonal transmitter content at the ganglionic side of the crush. However, even under these conditions, catecholamine fluorescence was not detected in axons projecting peripherally or centrally from the ganglia. Sympathetic noradrenergic nerves entered the ganglia and terminated within them. Accordingly, biochemical analyses of guinea-pig sensory ganglia revealed noradrenaline but no dopamine. In conclusion, catecholamines within guinea-pig sensory ganglia are confined to sympathetic nerves, which fulfill presently unknown functions. The TH-LI neurons themselves, however, lack any additional sign of catecholamine synthesis, and the presence of enzymatically active TH within these neurons is questionable.
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Affiliation(s)
- W Kummer
- Institute for Anatomy and Cell Biology, University of Heidelberg, FRG
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Duchen MR, Caddy KW, Kirby GC, Patterson DL, Ponte J, Biscoe TJ. Biophysical studies of the cellular elements of the rabbit carotid body. Neuroscience 1988; 26:291-311. [PMID: 3419588 DOI: 10.1016/0306-4522(88)90146-7] [Citation(s) in RCA: 107] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The carotid body is a major sensor of oxygen partial pressure in the arterial blood, and plays a role in the control of respiration. Despite extensive investigation of the structure, the cellular basis of the transduction mechanism remains poorly understood. We have developed a preparation of freshly dissociated cells from the rabbit carotid body, in which two cell types may be identified using morphological criteria. The preparation allows application of the patch clamp technique to characterize the properties of the cells which have otherwise proved difficult to study in situ. Carotid bodies of rabbits were dissociated using a combination of enzymatic and mechanical procedures. The dissociated preparation obtained consisted of clusters of spherical or ovoid cells of 12-15 microns in diameter and a distinct population of spherical cells of 8-10 microns diameter. Electron microscopic techniques were used to identify the cells present in the preparation. Again two populations of cells could be distinguished. A population of cells 10-12 microns in diameter, often found in clusters, possessed the dense-cored vesicles characteristic of Type I cells, while a population of smaller cells (diameter 5-7 microns) had peripherally condensed nuclear chromatin and fine cytoplasmic surface extensions characteristic of Type II cells. Patch clamp study of the cells showed that they represent two electrophysiologically distinct populations. The larger cells, corresponding to Type I cells, were found to be excitable, generating fast, sodium-dependent action potentials that were recorded both in the cell attached and whole cell recording configurations. The smaller Type II cells did not generate action potentials. Voltage clamp study of Type I cells allowed definition of a range of voltage-gated currents. These included an inactivating, tetrodotoxin-sensitive inward sodium current, a high threshold sustained inward calcium current, and outward potassium currents. A component of the outward current showed a dependence on voltage-gated calcium entry, and was blocked by cobalt or cadmium. Of the calcium-dependent current, a component was sensitive to apamin, and the remaining current was blocked by tetraethylammonium. Type II cells showed only a high threshold outward potassium current. These studies have thus revealed an electrophysiological differentiation that parallels the morphological differentiation of the cells of the carotid body. The Type I cell is essentially neuron-like in its properties, while the Type II cell appears to have properties resembling those of glial elements elsewhere in the nervous system.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- M R Duchen
- Department of Physiology, University College London, U.K
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Abstract
Previous studies have demonstrated that unmyelinated fibers in the cat carotid sinus nerve (CSN) are capable of inhibiting chemoreceptor activity from the carotid body. While the mechanism(s) underlying this phenomenon are unknown, it has been postulated that carotid body catecholamines may be involved in mediating this inhibitory effect. In this study, the in vitro cat carotid body-CSN preparation was used to investigate the effects of CSN stimulation on the release of [3H]catecholamines from the carotid body. The results showed that labeled catecholamines were released from this organ only when C-fibers were recruited by nerve stimulation.
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McDonald DM, Mitchell RA. The neural pathway involved in "efferent inhibition" of chemoreceptors in the cat carotid body. J Comp Neurol 1981; 201:457-76. [PMID: 7276260 DOI: 10.1002/cne.902010310] [Citation(s) in RCA: 36] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
This study was done to determine whether a pathway of efferent axons in the carotid sinus nerve is necessary for the phenomenon of "efferent inhibition" (inhibition induced in carotid body chemoreceptors by electrical stimulation of the carotid sinus nerve). Our approach was to eliminate efferent axons in the carotid sinus nerve of cats without destroying the sensory axons. This was achieved by cutting the ipsilateral glossopharyngeal and vagus nerves central to their sensory ganglia and/or by removing the nodose and superior cervical ganglia. In neurophysiological studies we found that the response of chemoreceptors in cats 10 days after surgery was the same as that in controls. chemoreceptor activity was decreased by electrical stimulation of the carotid sinus nerve and was increased by hypoxia and cyanide. In operated cats as in control animals, "efferent inhibition" was abolished by haloperidol and dihydroergotamine, drugs that block the inhibitory action of dopamine. Electron microscopic studies disclosed that the number of nerve endings in glomus cell/sheath cell complexes was not measurably different in control and experimental carotid bodies. By contrast, 10 days after the carotid sinus nerve was cut the number of nerve endings next to such ells was reduced by more than 99%. cutting the nerve roots and excising the ganglia eliminated most nerve endings on blood vessels: The number of noradrenergic-type nerve endings was reduced 99% and other types of nerve endings (presumptive cholinergic and peptidergic types) were reduced by more than 90%. Our experiments indicate that "efferent inhibition" is not abolished by operations that destroy inputs to blood vessels and to carotid boy glomus cells from (1) the nodose ganglion, (2) superior cervical ganglion, or from (3) neurons in the brain stem whose axons run in the glossopharyngeal or vagus nerves. We conclude that " efferent inhibition" may be caused by antidromic stimulation of sensory axons.
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deGroat WC, Nadelhaft I, Morgan C, Schauble T. The central origin of efferent pathways in the carotid sinus nerve of the cat. Science 1979; 205:1017-8. [PMID: 472721 DOI: 10.1126/science.472721] [Citation(s) in RCA: 36] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The application of horseradish peroxidase to the central cut end of the carotid sinus nerve of the cat produced retrograde labeling of neurons in the ipsilateral medulla in the region of the nucleus ambiguus at anterior-posterior coordinates -8 to -10.5. These data coupled with previous electrophysiological observations suggest that the nucleus ambiguus may be the origin of an efferent inhibitory pathway to the carotid body.
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Effect of hypoxia on the lactate dehydrogenase isoenzyme composition in the rat carotid body. Bull Exp Biol Med 1974. [DOI: 10.1007/bf00796649] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Capella C, Solcia E. Optical and electron microscopical study of cytoplasmic granules in human carotid body, carotid body tumours and glomus jugulare tumours. VIRCHOWS ARCHIV. B, CELL PATHOLOGY 1971; 7:37-53. [PMID: 4993473 DOI: 10.1007/bf02892077] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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Sampson SR. Effects of mecamylamine on responses of carotid body chemoreceptors in vivo to physiological and pharmacological stimuli. J Physiol 1971; 212:655-66. [PMID: 5557066 PMCID: PMC1395723 DOI: 10.1113/jphysiol.1971.sp009348] [Citation(s) in RCA: 34] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
1. Effects of mecamylamine on the spontaneous discharge rate of afferent fibres of carotid body chemoreceptors in vivo and their responses to ACh, NaCN, HCl and hypoxia were studied in sixteen cats.2. Cats were anaesthetized with sodium pentobarbitone, paralysed with gallamine triethiodide and artificially ventilated. Chemoreceptor excitants were injected into the common carotid artery; mecamylamine was given intravenously.3. Mecamylamine, 230 mug/kg or greater, failed to diminish either the rate of spontaneous discharge of carotid body chemoreceptors at high arterial oxygen tensions (greater than 130 mm Hg), or the responses of these receptors to NaCN (0.5-25 mug), HCl or hypoxic blood.4. Responses of chemoreceptor afferent fibres to ACh (1.0-50 mug) in the same preparations were either completely abolished or considerably reduced by mecamylamine.5. These data do not support the hypothesis of a cholinergic mechanism for the initiation of chemosensory discharges in the carotid body, either at rest or in response to stimuli such as NaCN, acid or hypoxia.
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Yates RD, Chen IL, Duncan D. Effects of sinus nerve stimulation on carotid body glomus cells. J Biophys Biochem Cytol 1970; 46:544-52. [PMID: 5527239 PMCID: PMC2107871 DOI: 10.1083/jcb.46.3.544] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The sinus nerve or sympathetic trunk was stimulated unilaterally in one group of adult cats or Syrian hamsters while in another group the sinus nerve or sympathetic trunk was cut unilaterally and the animals were given reserpine. In a third group, atropine was administered prior to sinus nerve stimulation. All tissues were processed for the detection of primary monoamines. The carotid bodies on the operated sides were compared with those on the unoperated sides of the same animal in order to determine if amine depletion occurred following the experimental procedures. After sinus nerve stimulation alone, the density of the granules in the glomus cells was decreased, but changes were not noted in the granules following sympathetic nerve stimulation. Sinus nerve stimulation after atropine administration resulted in no change in granule density. Sinus nerve transection followed by reserpine treatment resulted in a greater decrease in granule density on the unoperated than on the operated side. Transection of the sympathetic components to the carotid body followed by reserpine injections resulted in a decrease in granule density in the glomus cells on both the operated and unoperated sides. These results suggest that the sinus nerve must be intact for reserpine to exert an effect and that the sinus nerve may contain efferent fibers which modulate amine secretion.
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Biscoe TJ, Lall A, Sampson SR. Electron microscopic and electrophysiological studies on the carotid body following intracranial section of the glossopharyngeal nerve. J Physiol 1970; 208:133-52. [PMID: 5499751 PMCID: PMC1348776 DOI: 10.1113/jphysiol.1970.sp009110] [Citation(s) in RCA: 75] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
1. The innervation of carotid body Type I cells has been investigated in seventeen cats. At a sterile operation the glossopharyngeal and vagus nerve roots were cut intracranially on one side.2. From 1(1/2) to 378 days after the operation the carotid bodies were fixed in situ and prepared for electron microscopy. Nerve endings on Type I cells were found to degenerate with a prolonged time course. In each cat there was a decrease in the number of nerve endings on the operated side as compared with the non-operated side.3. Before the carotid bodies were fixed, recordings were made from chemoreceptor, and baroreceptor, afferent fibres in the sinus nerve on the operated side. The chemoreceptors responded in the usual way to changes in arterial O(2), CO(2) and pH; the injection of cyanide evoked a brisk response.4. It is concluded that the nerve endings on Type I cells are efferent rather than afferent and the cell bodies of their axons are probably in the brain stem.
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Chen IL, Yates RD. Ultrastructural studies of vagal paraganglia in Syrian hamsters. ZEITSCHRIFT FUR ZELLFORSCHUNG UND MIKROSKOPISCHE ANATOMIE (VIENNA, AUSTRIA : 1948) 1970; 108:309-23. [PMID: 5452908 DOI: 10.1007/bf00336522] [Citation(s) in RCA: 34] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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al-Lami F, Murray RG. Fine structure of the carotid body of Macaca mulata monkey. JOURNAL OF ULTRASTRUCTURE RESEARCH 1968; 24:465-78. [PMID: 4974631 DOI: 10.1016/s0022-5320(68)80049-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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Biscoe TJ, Sampson SR. Rhythmical and non-rhythmical spontaneous activity recorded from the central cut end of the sinus nerve. J Physiol 1968; 196:327-38. [PMID: 5652880 PMCID: PMC1351715 DOI: 10.1113/jphysiol.1968.sp008510] [Citation(s) in RCA: 77] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
1. Two types of spontaneous nervous activities have been recorded from the central cut end of the carotid sinus nerve of the cat.2. One type was composed of nerve potentials that exhibited a respiratory or cardiac rhythm, whose rate of firing was depressed by the pressor response to adrenaline, and that were found to arise from post-ganglionic fibres of the superior cervical ganglion.3. The other type of activity consisted of non-rhythmical nerve potentials whose rate of discharge increased 10-30 sec after the injection of adrenaline. The activity of these fibres also increased when the arterial oxygen tension was lowered or when the arterial carbon dioxide tension was raised.4. It is conceivable that either of these two groups of fibres, rather than the chemoreceptor afferent fibres, could provide the source of the microvesicle-containing nerve endings on the type 1 cells of the carotid body.5. A nerve was also described coursing from the sinus nerve to the hypoglossal nerve; the activity in it was sympathetic in origin.
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el-Lami F, Murray RG. Fine structure of the carotid body of normal and anoxic cats. Anat Rec (Hoboken) 1968; 160:697-718. [PMID: 5666660 DOI: 10.1002/ar.1091600405] [Citation(s) in RCA: 51] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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