Branchial receptors and cardiorespiratory reflexes in a neotropical fish, the tambaqui (Colossoma macropomum)

2000 ◽  
Vol 203 (7) ◽  
pp. 1225-1239 ◽  
Author(s):  
L. Sundin ◽  
S.G. Reid ◽  
F.T. Rantin ◽  
W.K. Milsom
Keyword(s):  
Buccal Cavity ◽  
Cranial Nerves ◽  
Breathing Frequency ◽  
Aquatic Surface Respiration ◽  
Neotropical Fish ◽  
Cardiorespiratory Control ◽  
Colossoma Macropomum ◽  
Before And After ◽  
Water Ph ◽  
Ventral Aorta

This study examined the location and physiological roles of branchial chemoreceptors involved in the cardiorespiratory responses to hypoxia and hypercarbia in a neotropical fish that exhibits aquatic surface respiration, the tambaqui (Colossoma macropomum). Fish were exposed to abrupt progressive environmental hypoxia (18. 6–1.3 kPa water P(O2)) and hypercarbia (water equilibrated with 5 % CO(2) in air, which lowered the water pH from 7.0 to 5.0). They were also subjected to injections of NaCN into the ventral aorta (to stimulate receptors monitoring the blood) and buccal cavity (to stimulate receptors monitoring the respiratory water). All tests were performed before and after selective denervation of branchial branches of cranial nerves IX and X to the gill arches. The data suggest that the O(2) receptors eliciting reflex bradycardia and increases in breathing frequency are situated on all gill arches and sense changes in both the blood and respiratory water and that the O(2) receptors triggering the elevation in systemic vascular resistance, breathing amplitude, swelling of the inferior lip and that induce aquatic surface respiration during hypoxia are extrabranchial, although branchial receptors also contribute to the latter two responses. Hypercarbia also produced bradycardia and increases in breathing frequency, as well as hypertension, and, while the data suggest that there may be receptors uniquely sensitive to changes in CO(2)/pH involved in cardiorespiratory control, this is based on quantitative rather than qualitative differences in receptor responses. These data reveal yet another novel combination for the distribution of cardiorespiratory chemoreceptors in fish from which teleologically satisfying trends have yet to emerge.

Cardiac and Respiratory Responses to Hypoxia in the Sea Raven, Hemitripterus americanus, and an Investigation of Possible Control Mechanisms

1971 ◽  
Vol 28 (4) ◽  
pp. 491-503 ◽  
Author(s):  
R. L. Saunders ◽  
A. M. Sutterlin
Keyword(s):  
Blood Pressure ◽  
Cranial Nerves ◽  
Aortic Pressure ◽  
Preliminary Evidence ◽  
Control Mechanisms ◽  
Sea Raven ◽  
Before And After ◽  
Wave Forms ◽  
Ventral Aorta ◽  
Hemitripterus Americanus

Responses of the sea raven (Hemitripterus americanus) to hypoxia consisted of an increase in rate and amplitude of breathing and an increase in dorsal and ventral aortic pressure. Changes in heart rate seldom occurred. Bilateral transection of cranial nerves IX and X resulted in a fall in dorsal aortic PO2 to a sustained low level but did not alter the dorsal and ventral aortic blood pressure or breathing responses induced by hypoxia.Pressure changes in the opercular cavity during breathing seldom exceeded.5 cm H2O and rarely exceeded 1 cm H2O under extreme hypoxia. There were no obvious differences in opercular pressure wave forms before and after bilateral section of nerves IX and X.An artificial "heart-gill" machine was devised with which blood PO2 could be altered outside the fish and the blood perfused into either the dorsal or ventral aorta. Breathing amplitude was increased by perfusing blood of low PO2 into the dorsal aorta. While maintaining dorsal aortic PO2 high and constant, increases in breathing amplitude were induced by low ambient PO2 levels.Vasomotor changes in blood pathways other than the gills probably contribute to the changes in blood pressure observed during hypoxia. Preliminary evidence for both central and peripheral sites of oxygen receptor activity is provided.

The relative roles of external and internal CO2versusH+ in eliciting the cardiorespiratory responses ofSalmo salarandSqualus acanthiasto hypercarbia

2001 ◽  
Vol 204 (22) ◽  
pp. 3963-3971 ◽  
Author(s):  
S. F. Perry ◽  
J. E. McKendry
Keyword(s):  
Cardiac Output ◽  
Sea Water ◽  
Buccal Cavity ◽  
Respiratory Acidosis ◽  
Systemic Resistance ◽  
Measured Variable ◽  
Cardiorespiratory Responses ◽  
Arterial Blood ◽  
Water Ph ◽  
Stimulation Of

SUMMARYFish breathing hypercarbic water encounter externally elevated PCO2 and proton levels ([H+]) and experience an associated internal respiratory acidosis, an elevation of blood PCO2 and [H+]. The objective of the present study was to assess the potential relative contributions of CO2versus H+ in promoting the cardiorespiratory responses of dogfish (Squalus acanthias) and Atlantic salmon (Salmo salar) to hypercarbia and to evaluate the relative contributions of externally versus internally oriented receptors in dogfish.In dogfish, the preferential stimulation of externally oriented branchial chemoreceptors using bolus injections (50 ml kg–1) of CO2-enriched (4 % CO2) sea water into the buccal cavity caused marked cardiorespiratory responses including bradycardia (–4.1±0.9 min–1), a reduction in cardiac output (–3.2±0.6 ml min–1 kg–1), an increase in systemic vascular resistance (+0.3±0.2 mmHg ml min–1 kg–1), arterial hypotension (–1.6±0.2 mmHg) and an increase in breathing amplitude (+0.3±0.09 mmHg) (means ± s.e.m., N=9–11). Similar injections of CO2-free sea water acidified to the corresponding pH of the hypercarbic water (pH 6.3) did not significantly affect any of the measured cardiorespiratory variables (when compared with control injections). To preferentially stimulate putative internal CO2/H+ chemoreceptors, hypercarbic saline (4 % CO2) was injected (2 ml kg–1) into the caudal vein. Apart from an increase in arterial blood pressure caused by volume loading, internally injected CO2 was without effect on any measured variable.In salmon, injection of hypercarbic water into the buccal cavity caused a bradycardia (–13.9±3.8 min–1), a decrease in cardiac output (–5.3±1.2 ml min–1 kg–1), an increase in systemic resistance (0.33±0.08 mmHg ml min–1 kg–1) and increases in breathing frequency (9.7±2.2 min–1) and amplitude (1.2±0.2 mmHg) (means ± s.e.m., N=8–12). Apart from a small increase in breathing amplitude (0.4±0.1 mmHg), these cardiorespiratory responses were not observed after injection of acidified water.These results demonstrate that, in dogfish and salmon, the external chemoreceptors linked to the initiation of cardiorespiratory responses during hypercarbia are predominantly stimulated by the increase in water PCO2 rather than by the accompanying decrease in water pH. Furthermore, in dogfish, the cardiorespiratory responses to hypercarbia are probably exclusively derived from the stimulation of external CO2 chemoreceptors, with no apparent contribution from internally oriented receptors.

Heat transfer between fish and ambient water

1976 ◽  
Vol 65 (1) ◽  
pp. 131-145 ◽  
Author(s):  
E. D. Stevens ◽  
A. M. Sutterlin
Keyword(s):  
Body Wall ◽  
Sea Water ◽  
The Body ◽  
Direct Transfer ◽  
Major Fraction ◽  
Metabolic Heat ◽  
Sea Raven ◽  
Before And After ◽  
Ventral Aorta ◽  
Hemitripterus Americanus

1. The ability of fish gills to transfer heat was measured by applying a heat pulse to blood in the ventral aorta and measuring it before and after passing through the gills of a teleost, Hemitripterus americanus. 2. 80–90% of heat contained in the blood is lost during passage through the gills. 3. The fraction of heat not lost during passage through the gills is due to direct transfer of heat between the afferent and efferent artery within the gill bar. 4. The major fraction of metabolic heat (70 - 90%) is lost through the body wall and fins of the sea raven in sea water at 5 degrees C; the remainder is lost through the gills.

Differential cardiorespiratory control elicited by activation of ventral medullary sites in mice

2000 ◽  
Vol 89 (2) ◽  
pp. 437-444 ◽  
Author(s):  
F. P. Tolentino-Silva ◽  
M. A. Haxhiu ◽  
P. Ernsberger ◽  
S. Waldbaum ◽  
I. A. Dreshaj
Keyword(s):  
Blood Pressure ◽  
Adrenergic Receptors ◽  
Excitatory Amino Acid ◽  
Signal Transduction Pathway ◽  
Ventrolateral Medulla ◽  
Respiratory Drive ◽  
Breathing Frequency ◽  
Cardiorespiratory Control ◽  
Blood Pressure Responses ◽  
Stimulation Of

We studied the respiratory and blood pressure responses to chemical stimulation of two regions of the ventral brainstem in mice: the rostral and caudal ventrolateral medulla (RVLM and CVLM, respectively). Stimulation of the RVLM by microinjections of the excitatory amino acid l-glutamate induced increases in diaphragm activity and breathing frequency, elevation of blood pressure (BP), and a slight increase in heart rate (HR). However, activation of the CVLM induced a decrease in breathing frequency, mainly due to prolongation of expiratory time (Te), and hypotension associated with a slight slowing of HR. Because adrenergic mechanisms are known to participate in the control of respiratory timing, we examined the role of α2-adrenergic receptors in the RVLM region in mediating these inhibitory effects. The findings demonstrated that blockade of the α2-adrenergic receptors within the RVLM by prior microinjection of SKF-86466 (an α2-adrenergic receptor blocker) significantly reduced changes in Te induced by CVLM stimulation but had little effect on BP responses. These results indicate that, in mice, activation of the RVLM increases respiratory drive associated with an elevation of BP, but stimulation of CVLM induces prolongation of Te via an α2-adrenergic signal transduction pathway.

scholarly journals NMDA receptors mediate peripheral chemoreceptor afferent input in the conscious rat

1998 ◽  
Vol 84 (3) ◽  
pp. 853-861 ◽  
Author(s):  
Patricia J. Ohtake ◽  
José E. Torres ◽  
Yair M. Gozal ◽  
Gavin R. Graff ◽  
David Gozal
Keyword(s):  
Nmda Receptor ◽  
Nmda Receptors ◽  
Receptor Activation ◽  
Sodium Cyanide ◽  
Respiratory Drive ◽  
Peripheral Chemoreceptor ◽  
Cardiorespiratory Control ◽  
Mk 801 ◽  
Ventilatory Responses ◽  
Before And After

N-methyl-d-aspartate (NMDA) glutamate receptors mediate critical components of cardiorespiratory control in anesthetized animals. The role of NMDA receptors in the ventilatory responses to peripheral and central chemoreceptor stimulation was investigated in conscious, freely behaving rats. Minute ventilation (V˙e) responses to 10% O2, 5% CO2, and increasing intravenous doses of sodium cyanide were measured in intact rats before and after intravenous administration of the NMDA receptor antagonist MK-801 (3 mg/kg). After MK-801, eupcapnic tidal volume (Vt) decreased while frequency increased, resulting in a modest reduction inV˙e. Inspiratory time (Ti) decreased, whereas expiratory time remained unchanged. TheV˙e responses to hypercapnia were qualitatively similar in control and MK-801 conditions, with slight reductions in respiratory drive (Vt/Ti) after MK-801. In contrast, responses to hypoxia were markedly attenuated after MK-801 and were primarily due to reduced frequency changes, whereas Vt was unaffected. Sodium cyanide doses associated with significantV˙eincreases were 5 and 50 μg/kg before and after MK-801, respectively. Thus 1-log shift to the right of individual dose-response curves occurred with MK-801. Selective carotid body denervation reducedV˙e during hypoxia by 70%, and residual hypoxic ventilatory responses were abolished after MK-801. These findings suggest that, in conscious rats, carotid and other peripheral chemoreceptor-mediated hypoxic ventilatory responses are critically dependent on NMDA receptor activation and that NMDA receptor mechanisms are only modestly involved during hypercapnia.

Localization of receptors causing hypoxic bradycardia in trout (Salmo gairdneri)

1978 ◽  
Vol 56 (6) ◽  
pp. 1260-1265 ◽  
Author(s):  
Frank M. Smith ◽  
David R. Jones
Keyword(s):  
Oxygen Tension ◽  
Buccal Cavity ◽  
Cranial Nerves ◽  
Gill Arch ◽  
Cardiac Response ◽  
Salmo Gairdneri ◽  
Acclimation Temperature ◽  
Tongue Depressor ◽  
Hypoxic Water ◽  
Biological Advantage

Receptors causing the cardiac response to environmental hypoxia have been located in rainbow trout (Salmo gairdneri). Intact, unrestrained trout, acclimated to7or 16 °C. showed a marked increase in ventilation and bradycardia when exposed to hypoxia at their acclimation temperature, In experiments designed to locate the site of receptors causing hypoxic bradycardia, the buccal cavity of a fish was divided into two chambers by a tongue depressor, allowing oxygen tension of water flowing over each set of gills lo be varied independently. Irrigating one set of gills with hypoxic water [Formula: see text] while flowing hyperoxic water [Formula: see text] over the other caused heart rate to fall from 42.2 ± 0.6 (± SEM) to 26.4 ± 0.5 (± SEM) beats/min after 1 min of hypoxic water flow. Dorsal aortic [Formula: see text] was always above that recorded when both sets of gills were flushed with normoxic water [Formula: see text]. Bilateral ligation of the efferent pseudobranch artery and the pseudobranch nerve (cranial nerve IX) had no effect on the cardiac response to irrigation of one set of gills by hypoxic water. Physical removal of, or section of the nerve supply (cranial nerves IX and X) to, the first gill arch eliminated hypoxic bradycardia. The biological advantage of hypoxic bradycardia is discussed and it is suggested that gill arch receptors may function to monitor and maintain oxygen tension of blood leaving the gills.

A role for NMDA receptors in posthypoxic frequency decline in the rat

1998 ◽  
Vol 274 (6) ◽  
pp. R1546-R1555 ◽  
Author(s):  
Sharon K. Coles ◽  
Paul Ernsberger ◽  
Thomas E. Dick
Keyword(s):  
Nmda Receptors ◽  
Receptor Activation ◽  
Respiratory Pattern ◽  
Breathing Frequency ◽  
Respiratory Response ◽  
Arterial Blood ◽  
Before And After ◽  
High Doses ◽  
The Brain ◽  
Nmda Receptor Activation

Posthypoxic frequency decline (PHFD) refers to the undershoot in respiratory frequency that follows brief hypoxic exposures. Lateral pontine neurons are required for PHFD. The neurotransmitters involved in the circuit that activate and/or are released by these pontine neurons regulating PHFD are unknown. We hypothesized that N-methyl-d-aspartate (NMDA) receptors are required for PHFD, because of the similarity in respiratory pattern after blocking lateral pontine activity or NMDA receptors. Furthermore, we hypothesized that the location of these NMDA receptors could be visualized by optimizing binding affinity with spermidine. In vagotomized, anesthetized rats ( n = 16), cardiorespiratory responses to hypoxia (8% O2, 30–90 s) were recorded before and after dizocilpine (10 μg-1 mg/kg iv), and NMDA receptors were mapped with [3H]dizocilpine ( n = 6). Dizocilpine elicited a dose-related effect on PHFD, blocking PHFD at high doses. Resting arterial blood pressure and breathing frequency decreased with high doses of dizocilpine, but the respiratory response to hypoxia remained intact. Our novel anatomical data indicate that NMDA receptors were widespread but distributed differentially in the brain stem. We conclude that NMDA receptors are located in pontine and medullary respiratory-related regions and that PHFD requires NMDA-receptor activation.

scholarly journals Can fishways restore river connectivity? A case study using β diversity as a method of assessment

2018 ◽  
Vol 30 (0) ◽  
Author(s):  
Hugo Marques ◽  
João Henrique Pinheiro Dias ◽  
Igor Paiva Ramos
Keyword(s):  
Multidimensional Scaling ◽  
Fish Assemblages ◽  
Neotropical Fish ◽  
Whitney Test ◽  
Β Diversity ◽  
Mantel Tests ◽  
Before And After ◽  
Method Of Assessment ◽  
Sørensen Index

Abstract Aim β diversity was used as an indicator to test the hypothesis that a fishway can increase river connectivity, as a reduction in the value of this metric indicates greater similarity among fish assemblages. Methods Quarterly sampling was performed with gillnets upstream and downstream of the Porto Primavera dam, Upper Paraná Basin, before the opening of the fishway between February 1999 and May 2001, and between February 2003 and May 2005 with the fishway in operation (10 samples per period/site). The correlation between the fish assemblages and sites was verified by applying two Mantel tests (downstream versus upstream before and one equivalent after the fishway) using the distance matrices generated by the Bray‐Curtis index. The β diversity between downstream and upstream was calculated using the Sørensen index for each sample for the comparison of such values before and after the operation of the fishway, which were tested with Asymptotic Wilcoxon-Mann-Whitney Test. To summarize changes in the structure of the fish assemblages between the sites and periods nonmetric multidimensional scaling (NMDS) was applied based on Bray-Curtis dissimilarities, using multi-response permutation procedures (MRPP). Results The Mantel tests showed no correlation between the upstream and downstream assemblages before the operation of the fishway but greater correlation after. β diversity was lower after than before the fishway, representing an increase in similarity between downstream and upstream with the fishway. MRPP analysis indicated that the fish assemblages between the sites differed more than was expected by chance, with smaller divergence between the sampling sites after the fishway (A = 0.08) than before it opened (A = 0.09). Conclusions Although fishways remain an incipient and controversial theme for neotropical fish, the Porto Primavera fishway appears to be effective in terms of the restoration of connectivity.

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