Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Chemoreceptor Cells”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 469 records · Page 26Linked to original sources
PubMed2002

Past-A, a novel proton-associated sugar transporter, regulates glucose homeostasis in the brain.

The ventral medullary surface (VMS) of the medulla oblongata is known to be the site of the central chemosensitive neurons in mammals. These neurons sense excess H+/CO2 dissolved in the CSF and induce hyperventilation. To elucidate the mechanism of neuronal cell adaptation to changes of H+/CO2, we screened for hypercapnia-induced genes in the VMS. Here, we report cloning and characterization of a novel gene called proton-associated sugar transporter-A (Past-A), which is induced in the brain after hypercapnia and mediates glucose uptake along the pH gradient. Past-A comprises 751 amino acid residues containing 12 membrane-spanning helices, several conserved sugar transport motifs, three proline-rich regions, and leucine repeats. Past-A transcript was expressed predominantly in the brain. Moreover, the Past-A-immunoreactive neural cells were found in the VMS of the medulla oblongata, and the number of immunoreactive cells was increased by hypercapnic stimulation. Transient transfection of Past-A in COS-7 cells leads to the expression of a membrane-associated 82 kDa protein that possesses a glucose transport activity. The acidification of extracellular medium facilitated glucose uptake, whereas the addition of carbonyl cyanide m-chlorophenylhydrazone, a protonophore, inhibited glucose import. Together, our results indicate that Past-A is a brain-specific glucose transporter that may represent an adaptation mechanism regulating sugar homeostasis in neuronal cells after hypercapnia.

Administration, Inhalation↗
PubMed1982

[Chemosensitive structures of the medulla oblongata participate in blood pressure regulation and belong to APUD-system].

It was shown in 25 experiments on anesthetized spontaneously breathing and immobilized artificially ventilated cats that the cooling of the intermediate chemosensitive area of the ventral surface of medulla oblongata to 20-22 degrees C is followed by depressor reaction that is more pronounced after preliminary occlusion of the sinocarotid and vagus nerves. Two types of apudocytes were revealed in this brain area with the use of the histochemical and immunohistochemical techniques. The first type cells are typically nervous and contain noradrenaline. The second type apudocytes adjacent to the microvascular wall showed melatonin and its precursors. It is assumed that the cells detected participate in the arterial pressure control.

APUD Cells↗
PubMed1997

Synapse formation and hypoxic signalling in co-cultures of rat petrosal neurones and carotid body type 1 cells.

1. To investigate synaptic mechanisms mediating chemosensory signalling in the carotid body, we developed co-cultures of chemoreceptor type 1 cell clusters and dissociated petrosal neurones (PNs) from 7- to 14-day-old rat pups and tested for functional connectivity in CO2-HCO3(-)-or Hepes-buffered medium at approximately 35 degrees C. 2. When cultured without type 1 cells, PNs were almost always quiescent (n = 104) and unresponsive to hypoxia (Po2 = 5-25 mmHg) during perforated patch, whole-cell recordings of membrane potential or voltage-activated currents; in contrast, many PNs (77 out of 170) that were juxtaposed to type 1 cell clusters in co-culture displayed spontaneous activity, comprising spikes and subthreshold potentials (SSPs) that resembled synaptic potentials. 3. Additional tests suggested that de novo chemical synapses developed between PNs and type 1 cell clusters in vitro. For example: (i) the spontaneous activity was reversibly suppressed by substituting low calcium-high magnesium in the bath; (ii) SSPs had variable amplitudes and persisted following action potential blockade with TTX (1 microM); (iii) the interval distribution between successive spontaneous events appeared random; and (iv) the frequency of spontaneous potentials was diminished (reversibly) by the nicotinic antagonist hexamethonium (100 microM), suggesting contributions from the spontaneous release of ACh. 4. Many complexes of 'juxtaposed' PNs and type 1 clusters were physiologically functional, since exposure to hypoxia caused a reversible depolarization and/or increased spike discharge in approximately 30% of such neurones (n = 140). The hypoxia-induced spike discharge persisted in the presence of the dopamine D2 receptor blocker spiperone (10-50 microM; n = 5); however, this discharge was reversibly inhibited by 100-200 microM hexamethonium, suggesting that it was mediated, at least in part, by ACh acting through nicotinic receptors. 5. The hypoxia-induced spike discharge and frequency of spontaneous potentials in co-cultured PNs were reversibly suppressed when the buffer was switched from CO2-HCO3- to Hepes (10 mM) at pH 7.4; further, 'functional' PNs that displayed spontaneous activity and/or hypoxia-induced responses in co-culture were encountered more frequently in CO2-HCO3- (> or = 40%) than in Hepes (< or = 26%) buffer. 6. We conclude that functional chemical synapses can develop de novo in cultures of carotid body type 1 cells and PNs and that ACh is probably an important excitatory neurotransmitter secreted from type 1 cells during hypoxic chemotransduction in the rat carotid body.

Acetylcholine↗
PubMed1997

Taste sensilla of flies: function, central neuronal projections, and development.

Taste sensilla of flies are composed of only a few cells, all of which have different functions. Depending on the species and on the sensillum type, there are from 2-5 neurons, each of which has its own stimulus specificity, and each of which makes a different contribution to the fly's behavior. In addition, taste sensilla include several nonneuronal cells that are important both for the development of the sensillum and for its functioning. The component cells of a sensillum derive from a single epidermal precursor according to a stereotyped sequence of mitoses. This review focuses on the different phenotypes of the component cells of taste sensilla, particularly the stimulus sensitivity and central neuronal anatomy of the receptor neurons, and on the development of this multicellular organ from a single precursor cell.

Animals↗
PubMed2000

O2-sensing after carotid chemodenervation: hypoxic ventilatory responsiveness and upregulation of tyrosine hydroxylase mRNA in brainstem catecholaminergic cells.

Ventilatory responses to acute and long-term hypoxia are classically triggered by carotid chemoreceptors. The chemosensory inputs are carried within the carotid sinus nerve to the nucleus tractus solitarius and the brainstem respiratory centres. To investigate whether hypoxia acts directly on brainstem neurons or secondarily via carotid body inputs, we tested the ventilatory responses to acute and long-term hypoxia in rats with bilaterally transected carotid sinus nerves and in sham-operated rats. Because brainstem catecholaminergic neurons are part of the chemoreflex pathway, the ventilatory response to hypoxia was studied in association with the expression of tyrosine hydroxylase (TH). TH mRNA levels were assessed in the brainstem by in situ hybridization and hypoxic ventilatory responses were measured in vivo by plethysmography. After long-term hypoxia, TH mRNA levels in the nucleus tractus solitarius and ventrolateral medulla increased similarly in chemodenervated and sham-operated rats. Ventilatory acclimatization to hypoxia developed in chemodenervated rats, but to a lesser extent than in sham-operated rats. Ventilatory response to acute hypoxia, which was initially low in chemodenervated rats, was fully restored within 21 days in long-term hypoxic rats, as well as in normoxic animals which do not overexpress TH. Therefore, activation of brainstem catecholaminergic neurons and ventilatory adjustments to hypoxia occurred independently of carotid chemosensory inputs. O2-sensing mechanisms unmasked by carotid chemodenervation triggered two ventilatory adjustments: (i) a partial acclimatization to long-term hypoxia associated with TH upregulation; (ii) a complete restoration of acute hypoxic responsivity independent of TH upregulation.

Adaptation, Physiological↗
PubMed1989

Chemoreceptive and mechanoreceptive paraneurons in the tongue.

Chemoreceptive and mechanoreceptive paraneurons in the tongue include gustatory cells and basal cells of the taste buds, Merkel cells in the lingual epithelium and Merkel or Grandry corpuscles in avian subepithelial connective tissue. Neuron-specific enolase immunoreactivity is recognized in the basal cells, a type of Merkel cells, in the taste buds of teleost fishes and amphibia, certain taste bud cells of mammals and the Merkel cells in birds. The present study also concerns itself with the ultrastructural features of the gustatory cells of the rabbit taste buds, and the Merkel cells of the finch tongue. The functional significance of the dense-cored granules in the gustatory cell is still enigmatic. On the other hand, the dense-cored granules in the Merkel cells may have dual functions storing both neurotransmitters and local hormones. Shortly after giving a mechanical stimulus to the finch tongue, we could demonstrate massive exocytotic changes of the Merkel cell granules.

Amphibians↗
PubMed1976

Identification of the epidermal "Stiftchenzellen" of frog tadpoles by electron microscopy.

Differentiated surface epidermal cells observed in the skin of tadpoles of Rana temporaria by electron microscopy have been identified with the Stiftchenzellen originally described by Kölliker in 1885. The cells have apical microvilli or a single apical projection and appear to have synaptic associations with nerve fibres in the epidermis. The distribution, dimensions and structure of the cells are in agreement with descriptions from le cells are sensory in nature. In addition, there are fine structural resemblances to the gustatory cells of fish and of amphibians which suggest that the Stiftchenzellen are chemoreceptors.

Animals↗