scholarly journals Control of gill ventilation and air-breathing in the bowfin amia calva

1999 ◽  
Vol 202 (1) ◽  
pp. 87-94
Author(s):  
M.S. Hedrick ◽  
D.R. Jones
Keyword(s):  
Bladder Volume ◽  
Control Fish ◽  
Type I ◽  
Type Ii ◽  
Afferent Pathways ◽  
Air Breathing ◽  
Gas Bladder ◽  
Stretch Receptors ◽  
Gill Ventilation ◽  
Amia Calva

The purpose of this study was to investigate the roles of branchial and gas bladder reflex pathways in the control of gill ventilation and air-breathing in the bowfin Amia calva. We have previously determined that bowfin use two distinct air-breathing mechanisms to ventilate the gas bladder: type I air breaths are characterized by exhalation followed by inhalation, are stimulated by aquatic or aerial hypoxia and appear to regulate O2 gas exchange; type II air breaths are characterized by inhalation alone and possibly regulate gas bladder volume and buoyancy. In the present study, we test the hypotheses (1) that gill ventilation and type I air breaths are controlled by O2-sensitive chemoreceptors located in the branchial region, and (2) that type II air breaths are controlled by gas bladder mechanosensitive stretch receptors. Hypothesis 1 was tested by examining the effects of partial or complete branchial denervation of cranial nerves IX and X to the gill arches on gill ventilation frequency (fg) and the proportion of type I air breaths during normoxia and hypoxia; hypothesis II was tested by gas bladder inflation and deflation. Following complete bilateral branchial denervation, fg did not differ from that of sham-operated control fish; in addition, fg was not significantly affected by aquatic hypoxia in sham-operated or denervated fish. In sham-operated fish, aquatic hypoxia significantly increased overall air-breathing frequency (fab) and the percentage of type I breaths. In fish with complete IX-X branchial denervation, fab was also significantly increased during aquatic hypoxia, but there were equal percentages of type I and type II air breaths. Branchial denervation did not affect the frequency of type I air breaths during aquatic hypoxia. Gas bladder deflation via an indwelling catheter resulted in type II breaths almost exclusively; furthermore, fab was significantly correlated with the volume removed from the gas bladder, suggesting a volume-regulating function for type II air breaths. These results indicate that chronic (3–4 weeks) branchial denervation does not significantly affect fg or type I air-breathing responses to aquatic hypoxia. Because type I air-breathing responses to aquatic hypoxia persist after IX-X cranial nerve denervation, O2-sensitive chemoreceptors that regulate air-breathing may be carried in other afferent pathways, such as the pseudobranch. Gas bladder deflation reflexly stimulates type II breaths, suggesting that gas bladder volume-sensitive stretch receptors control this particular air-breathing mechanism. It is likely that type II air breaths function to regulate buoyancy when gas bladder volume declines during the inter-breath interval.

THE EFFECTS OF ALTERED AQUATIC AND AERIAL RESPIRATORY GAS CONCENTRATIONS ON AIR-BREATHING PATTERNS IN A PRIMITIVE FISH (AMIA CALVA)

1993 ◽  
Vol 181 (1) ◽  
pp. 81-94 ◽  
Author(s):  
M. S. Hedrick ◽  
D. R. Jones
Keyword(s):  
Air Flow ◽  
The Body ◽  
Type I ◽  
Type Ii ◽  
Breathing Frequency ◽  
Breathing Patterns ◽  
Flow Measurements ◽  
Air Breathing ◽  
Gas Bladder ◽  
Amia Calva

The mechanisms and physiological control of air-breathing were investigated in an extant halecomorph fish, the bowfin (Amia calva). Air flow during aerial ventilation was recorded by pneumotachography in undisturbed Amia calva at 20–24°C while aquatic and aerial gas concentrations were independently varied. Separation of aquatic and aerial gases was used in an attempt to determine whether Amia calva monitor and respond to changes in the external medium per se or to changes in dissolved gases within the body. Air flow measurements revealed two different types of ventilatory patterns: type I air-breaths were characterized by exhalation followed by inhalation; type II air-breaths, which have not been described previously in Amia calva, consisted of single inhalations with no expiratory phase. Expired volume (Vexp) for type I breaths ranged from 11.6+/−1.1 to 26.7+/− 2.9 ml kg-1 (95 % confidence interval; N=6) under normoxic conditions and was unaffected by changes in aquatic or aerial gases. Gas bladder volume (VB), determined in vitro, was 80 ml kg-1; the percentage of gas exchanged for type I breaths ranged from 14 to 33 % of VB in normoxia. Fish exposed to aquatic and aerial normoxia (PO2=19-21 kPa), or aerial hypercapnia (PCO2=4.9 kPa) in normoxic water, used both breath types with equal frequency. Aquatic or aerial hypoxia (PO2=6-7 kPa) significantly increased air-breathing frequency in four of eight fish and the ventilatory pattern changed to predominantly type I air-breaths (75–92 % of total breaths). When fish were exposed to 100 % O2 in the aerial phase while aquatic normoxia or hypoxia was maintained, air-breathing frequency either increased or did not change. Compared with normoxic controls, however, type II breaths were used almost exclusively (more than 98 % of total breaths). Type I breaths appear to be under feedback control from O2-sensitive chemoreceptors since they were stimulated by aquatic or aerial hypoxia and were nearly abolished by aerial hyperoxia. These results also indicate that Amia calva respond to changes in intravascular PO2; however, externally facing chemoreceptors that stimulate air-breathing in aquatic hypoxia cannot be discounted. Type II air- breaths, which occurred in aerial hyperoxia, despite aquatic hypoxia, appear to be stimulated by reductions of VB, suggesting that type II breaths are controlled by volume-sensitive gas bladder stretch receptors. Type II breaths are likely to have a buoyancy-regulating function.

PERIODIC AIR-BREATHING BEHAVIOUR IN A PRIMITIVE FISH REVEALED BY SPECTRAL ANALYSIS

1994 ◽  
Vol 197 (1) ◽  
pp. 429-436
Author(s):  
M Hedrick ◽  
S Katz ◽  
D Jones
Keyword(s):  
Lung Ventilation ◽  
Phylogenetic Position ◽  
Breath Holding ◽  
Type I ◽  
Type Ii ◽  
Experimental Conditions ◽  
Air Breathing ◽  
Ventilatory Pattern ◽  
Gas Bladder ◽  
Amia Calva

The ventilatory patterns of air-breathing fish are commonly described as 'arrhythmic' or 'irregular' because the variable periods of breath-holding are punctuated by seemingly unpredictable air-breathing events (see Shelton et al. 1986). This apparent arrhythmicity contrasts with the perceived periodism or regularity in the gill ventilation patterns of some fish and with lung ventilation in birds and mammals. In this sense, periodism refers to behaviour that occurs with a definite, recurring interval (Bendat and Piersol, 1986). The characterisation of aerial ventilation patterns in fish as 'aperiodic' has been generally accepted on the basis of qualitative examination and it remains to be validated with rigorous testing. The bowfin, Amia calva (L.), is a primitive air-breathing fish that makes intermittent excursions to the air­water interface to gulp air, which is transferred to its well-vascularized gas bladder. Its phylogenetic position as the only extant member of the sister lineage of modern teleosts affords a unique opportunity to examine the evolution of aerial ventilation and provides a model for the examination of ventilatory patterns in primitive fishes. To establish whether Amia calva exhibit a particular pattern of air-breathing, we examined time series records of aerial ventilations from undisturbed fish over long periods (8 h). These records were the same as those used to calculate average ventilation intervals under a variety of experimental conditions (Hedrick and Jones, 1993). Their study also reported the occurrence of two distinct breath types. Type I breaths were characterised by an exhalation followed by an inhalation, whereas type II breaths were characterised by inhalation only. It was also hypothesized that the type I breaths were employed to meet oxygen demands, whereas the type II breaths were used to regulate gas bladder volume. However, they did not investigate the potential presence of a periodic ventilatory pattern. We now report the results of just such an analysis of ventilatory pattern that demonstrates a clear periodism to air-breathing in a primitive fish.

The Effects of Branchial Denervation and Pseudobranch Ablation on Cardioventilatory Control in an Air-Breathing Fish

1991 ◽  
Vol 161 (1) ◽  
pp. 347-365 ◽  
Author(s):  
DAVID J. McKENZIE ◽  
MARK L. BURLESON ◽  
DAVID J. RANDALL
Keyword(s):  
Cardiovascular Responses ◽  
Sodium Cyanide ◽  
Air Breathing ◽  
Ventilatory Responses ◽  
Reflex Bradycardia ◽  
Afferent Information ◽  
Gill Ventilation ◽  
Air Ventilation ◽  
Amia Calva

Present address and address for reprint requests: Istituto di Scienze Farmacologiche, via Balzaretti 9, Università di Milano, Milano 20133, Italy. The role of sensory afferent information from the gills of Amia calva in cardiovascular and ventilatory control was investigated by bilateral branchial denervation and pseudobranch ablation. Aquatic hypoxia or 1 mg of sodium cyanide (NaCN) in the water flowing over the gills stimulated bradycardia, and gill and air ventilation in sham-operated fish. Sodium cyanide, noradrenaline (NA) and adrenaline (A) infusion into the dorsal aorta increased gill ventilation, and NA and A infusion also stimulated tachycardia and an increase in blood pressure. Following denervation and pseudobranch ablation, O2 consumption (V·OO2), airbreathing frequency (fAB) and arterial O2 tension (PaOO2) declined, and circulating NA levels increased, as compared with sham-operated fish. Cardiovascular and air-breathing responses to hypoxia were abolished and gill ventilatory responses attenuated. All ventilatory and cardiovascular responses to NaCN were abolished and gill ventilatory responses to NA and A were attenuated in animals following denervation and pseudobranch ablation. These results demonstrate that O2-sensitive chemoreceptors in the gills and pseudobranch control reflex bradycardia and air-breathing responses in Amia, but that gill ventilatory responses to hypoxia, NA and A are partially mediated by extrabranchial mechanisms. Plasma NA levels increased during hypoxia in shamoperated and denervated animals, indicating that circulating NA may have mediated gill ventilatory responses in denervated animals.

scholarly journals Characteristics of Mechanoreceptors in the Air-Breathing Organ of the Holostean Fish, Amia Calva

1985 ◽  
Vol 117 (1) ◽  
pp. 389-399 ◽  
Author(s):  
WILLIAM K. MILSOM ◽  
DAVID R. JONES
Keyword(s):  
Carbon Dioxide ◽  
Threshold Level ◽  
Lung Inflation ◽  
Air Breathing ◽  
Partial Pressures ◽  
Stretch Receptors ◽  
Single Nerve ◽  
Amia Calva ◽  
Single Nerve Fibre ◽  
Ventral Wall

Single nerve fibre discharge was recorded from mechanoreceptors associated with the air-breathing organ in double-pithed specimens of the bowfin, Amia calva L. These receptors were innervated by the vagus nerve and although their exact location was difficult to determine, most appeared to be located along the anterio-ventral wall of the single lung. All receptors increased tonic discharge with step increases in lung volume, above a threshold level, and were slowly adapting. There was a dynamic, rate-sensitive burst of activity associated with lung inflation and a dynamic, rate-sensitive inhibition of discharge associated with deflation. These responses were qualitatively similar to those of the tonic stretch receptors found in fish swimbladder and mammalian gut. All receptors were insensitive to changes in intrapulmonary partial pressures of oxygen and carbon dioxide. These observations suggest that receptors capable of transducing the rate, as well as the degree, of inflation and deflation are associated with primitive lungs, and may have arisen from tonic gut receptors.

An Examination of Central Chemosensitivity in an Air-Breathing Fish (Amia Calva)

1991 ◽  
Vol 155 (1) ◽  
pp. 165-174 ◽  
Author(s):  
M. S. HEDRICK ◽  
M. L. BURLESON ◽  
D. R. JONES ◽  
W. K. MILSOM
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Cerebral Ventricles ◽  
Air Breathing ◽  
Central Chemosensitivity ◽  
Central Chemoreceptors ◽  
Gill Ventilation ◽  
Amia Calva ◽  
Affect Heart Rate

The role of central chemosensitivity in the control of ventilation in fishes was investigated directly by perfusing a mock extradural fluid (EDF) through the cranial space in the medullary region of conscious air-breathing fish, Amia calva. Perfusions with Sudan Black dye showed that the mock EDF communicated with the cerebrospinal fluid (CSF) and entered the cerebral ventricles. Altering the PO2, PCO2 and/or pH of the mock EDF had no effect on gill- or air-breathing rates, heart rate or blood pressure during exposure to normoxic water. Aquatic hypoxia, however, stimulated gill ventilation and elevated blood pressure, but did not affect heart rate; altering the gas tensions and/or pH of mock EDF still had no effect on recorded variables. Sodium cyanide (NaCN) added to the mock EDF caused struggling at concentrations above 500 μgml−1, but did not uniformly stimulate ventilation. These results suggest that central chemoreceptors, which mediate cardiovascular or ventilatory reflexes, are absent in Amia.

scholarly journals The Transition to Air Breathing in Fishes: II. Effects of Hypoxia Acclimation on the Bimodal Gas Exchange of Ancistrus Chagresi (Loricariidae)

1983 ◽  
Vol 102 (1) ◽  
pp. 157-173 ◽  
Author(s):  
JEFFREY B. GRAHAM
Keyword(s):  
Gas Exchange ◽  
Exchange Capacity ◽  
The Body ◽  
Control Fish ◽  
Air Breathing ◽  
O2 Partial Pressure ◽  
Gill Ventilation ◽  
Ventilation Rates ◽  
Hypoxia Acclimation ◽  
Co2 Release

The armoured catfish, Ancistrus chagresi, is a facultative air breather and uses its stomach as an air-breathing organ (ABO). Comparisons of control fish and fish that had become acclimated to hypoxia and air breathing for 14–21 days were carried out to assess the effects of this treatment on bimodal (aerial and aquatic) gas exchange capacity. Hypoxia acclimation elicits physiological and biochemical changes that enable A. chagresi to increase O2 utilization both by its gills in hypoxic water and by its ABO. Compared with control fish, hypoxia-acclimated Ancistrus have a higher blood--O2 affinity and more haemoglobin (Hb) and can maintain a higher aquatic oxygen consumption rate (VO2) in hypoxic (Pw, Ow, O2, = 5–20 mmHg) water. They also have a 25% larger ABO volume, are able to hold each air breath longer, and can reduce ABO O2 partial pressure to a lower level. In both groups, respiratory CO2-release occurs primarily through the gills. An air breath instantly causes tachycardia and a reduction in the frequency and amplitude of branchial ventilation. Their lower cardiac and gill ventilation rates in hypoxia and during air breathing suggest that hypoxia-acclimated fish are more adapted for hypoxia than are control fish. During the period an air breath is held in the ABO, hypoxia-acclimated fish exhibit more coordinated phase shifts in gill ventilation and cardiac rates. These may favour an initial phase of efficient aerial O2 uptake from the ABO and transport through the body followed by a period of aquatic CO2 release from the gills.

Heat-Etching with a Bullivant Type II Simple Freeze-Cleave Device

1970 ◽  
Vol 28 ◽  
pp. 106-107 ◽  
Author(s):  
Ronald S. Weinstein ◽  
N. Scott McNutt
Keyword(s):  
New Zealand ◽  
General Hospital ◽  
Massachusetts General Hospital ◽  
Type I ◽  
Type Ii ◽  
Collaborative Effort ◽  
Temperature And Pressure ◽  
The University

The Type I simple cold block device was described by Bullivant and Ames in 1966 and represented the product of the first successful effort to simplify the equipment required to do sophisticated freeze-cleave techniques. Bullivant, Weinstein and Someda described the Type II device which is a modification of the Type I device and was developed as a collaborative effort at the Massachusetts General Hospital and the University of Auckland, New Zealand. The modifications reduced specimen contamination and provided controlled specimen warming for heat-etching of fracture faces. We have now tested the Mass. General Hospital version of the Type II device (called the “Type II-MGH device”) on a wide variety of biological specimens and have established temperature and pressure curves for routine heat-etching with the device.

Labelling of non-A, non-B hepatitis infected chimpanzee hepatocytes with nuclease-gold conjugates

1984 ◽  
Vol 42 ◽  
pp. 250-251
Author(s):  
G. D. Gagne ◽  
M. F. Miller ◽  
D. A. Peterson
Keyword(s):  
Endoplasmic Reticulum ◽  
Experimental Infection ◽  
Uranyl Acetate ◽  
Type I ◽  
Cellular Injury ◽  
Type Ii ◽  
Tubular Structures ◽  
Type Iii ◽  
Type Iv ◽  
Infected Chimpanzee

Experimental infection of chimpanzees with non-A, non-B hepatitis (NANB) or with delta agent hepatitis results in the appearance of characteristic cytoplasmic alterations in the hepatocytes. These alterations include spongelike inclusions (Type I), attached convoluted membranes (Type II), tubular structures (Type III), and microtubular aggregates (Type IV) (Fig. 1). Type I, II and III structures are, by association, believed to be derived from endoplasmic reticulum and may be morphogenetically related. Type IV structures are generally observed free in the cytoplasm but sometimes in the vicinity of type III structures. It is not known whether these structures are somehow involved in the replication and/or assembly of the putative NANB virus or whether they are simply nonspecific responses to cellular injury. When treated with uranyl acetate, type I, II and III structures stain intensely as if they might contain nucleic acids. If these structures do correspond to intermediates in the replication of a virus, one might expect them to contain DNA or RNA and the present study was undertaken to explore this possibility.

Comparative surface and ultrastructural views of methylotrophic bacteria by TEM, STEM, SE, and freeze-etch electron microscopy.

1987 ◽  
Vol 45 ◽  
pp. 792-793
Author(s):  
T.A. Fassel ◽  
M.J. Schaller ◽  
M.E. Lidstrom ◽  
C.C. Remsen
Keyword(s):  
Cytoplasmic Membrane ◽  
Structural Features ◽  
Methylotrophic Bacteria ◽  
Type I ◽  
Type Ii ◽  
Membrane Complex ◽  
Oxidation Of Methane ◽  
Methane Oxidizing Bacteria ◽  
Wall Structures ◽  
Methylomonas Albus

Methylotrophic bacteria play an Important role in the environment in the oxidation of methane and methanol. Extensive intracytoplasmic membranes (ICM) have been associated with the oxidation processes in methylotrophs and chemolithotrophic bacteria. Classification on the basis of ICM arrangement distinguishes 2 types of methylotrophs. Bundles or vesicular stacks of ICM located away from the cytoplasmic membrane and extending into the cytoplasm are present in Type I methylotrophs. In Type II methylotrophs, the ICM form pairs of peripheral membranes located parallel to the cytoplasmic membrane. Complex cell wall structures of tightly packed cup-shaped subunits have been described in strains of marine and freshwater phototrophic sulfur bacteria and several strains of methane oxidizing bacteria. We examined the ultrastructure of the methylotrophs with particular view of the ICM and surface structural features, between representatives of the Type I Methylomonas albus (BG8), and Type II Methylosinus trichosporium (OB-36).

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