Oxygen exchange and vascular resistance in the totally perfused rainbow trout

1978 ◽  
Vol 234 (5) ◽  
pp. R201-R208 ◽  
Author(s):  
C. M. Wood ◽  
B. R. McMahon ◽  
D. G. McDonald
Keyword(s):  
Vascular Resistance ◽  
Gill Tissue ◽  
Aortic Pressure ◽  
Salmo Gairdneri ◽  
Arterial Oxygenation ◽  
O2 Uptake ◽  
Perfusion Flow ◽  
Internal Component ◽  
External Component

A whole trout preparation (Salmo gairdneri) externally ventilated with water and internally perfused with artificial medium via a cardiac pump is discribed for the study of O2 exchange and vascular resistance. As cardiac output (Q) was raised, ventral and dorsal aortic pressures increased while branchial (Rg) and systemic (Rs) vascular resistances fell, reflecting considerable passive distensibility. Arterial oxygenation was negative at low Qs due to significant internal O2 demand by the gill tissue, but increased to zero or positive values at intermediate Qs, and eventually declined at high Qs because of transit time limitation. O2 uptake from the ventilatory flow rose with increasing Q. Epinephrine (10(-5) M) decreased Rg, increased Rs, and enhanced arterial oxygenation. Artificial elevation of dorsal aortic pressure decreased Rg but did not affect arterial oxygenation. A 10-fold elevation of ventilatory flow increased arterial oxygenation but did not alter Rg or Rs. Endogenous metabolism of branchial tissue accounted for 11.7% of resting O2 uptake in vivo, and comprised an internal component taking O2 from perfusion flow and an external component drawing O2 from ventilatory flow.

Gas Transfer in a Spontaneously Ventilating, Blood-Perfused Trout Preparation

1982 ◽  
Vol 101 (1) ◽  
pp. 17-34
Author(s):  
PETER S. DAVIE ◽  
CHARLES DAXBOECK ◽  
STEVE F. PERRY ◽  
DAVID J. RANDALL
Keyword(s):  
Carbon Dioxide ◽  
Gas Exchange ◽  
Vascular Resistance ◽  
Respiratory Quotient ◽  
Venous Blood ◽  
Cardiovascular Responses ◽  
Systemic Circulation ◽  
Aortic Pressure ◽  
Gas Transfer

1. A spontaneously ventilating, blood-perfused trout preparation is described and its suitability for the study of gas exchange in fish assessed. 2. Cardiovascular dynamics closely approximated those found in vivo; perfusion flow rate (Q) = 1·62 ml−1.100 g−1, ventral aortic pressure (VAP) = 58·8 cm H2O, dorsal aortic pressure (DAP) = 34·8 cm H2O. 3. Gas exchange characteristics in the branchial and systemic circulations also were similar to those described for resting, intact rainbow trout. All preparations showed consistent oxygen uptake (Mg,O2, 1·17 μmol. min−1.100 g−1) and carbon dioxide excretion rates (Mg,CO2, 2·05 μmol. min−1.100 g−1) across the gills. Across the systemic circulation, oxygen was extracted (Ms,O2, 1·97 μmol. min−1.100 g−1) and carbon dioxide produced by the metabolizing tissue (Ms,CO2, 1·63 μmol. min−1.100 g−1). The respiratory quotient (REg) for gas transfer across the gills was 1·85. This high value was a reflection of the fact that much more oxygen than carbon dioxide was added to venous blood in the tonometer. The respiratory quotient for the tissues (RQs) was 0·83, a more reasonable value. Breathing rate (fg) was maintained at 69·4 ventilations.min−1. 4. The mean vascular resistance of blood-perfused gills (Rg) was 14·2 cm H2O.ml−1.min.100 g−1, a value higher than that usually measured in vivo. Mean systemic vascular resistance (Rs) was 19·2 cm H2O.ml−1.min.100 g−1 which is similar to that measured in intact fish. 5. Cardiovascular responses to hypoxia and adrenergic responses in the branchial and systemic circulations of these preparations also closely approximated those found in vivo. 6. This preparation is deemed suitable for studies of the cardiovascular system as well as gas transfer. The results from these experiments are representative of the in vivo condition in fish.

A Critical Examination of the Physical and Adrenergic Factors Affecting Blood Flow Through the Gills of the Rainbow Trout

1974 ◽  
Vol 60 (1) ◽  
pp. 241-265 ◽  
Author(s):  
CHRIS M. WOOD
Keyword(s):  
Vascular Resistance ◽  
Aortic Pressure ◽  
Pressure Differential ◽  
Salmo Gairdneri ◽  
Critical Examination ◽  
Flow Profile ◽  
Passive Resistance ◽  
Factors Affecting ◽  
Secondary Lamellae ◽  
Differential Flow

1. Perfusion of the whole gill of Salmo gairdneri with a Newtonian medium under different afferent and efferent pressures has revealed considerable passive distensibility in the branchial vasculature. A capacity for autoregulation may exist. 2. Changes in dorsal aortic pressure are relatively more effective than changes in ventral aortic pressure in altering branchial vascular resistance. 3. Measurements of changes in vascular tone in the gills determined as the ratio of resistances in the experimental and the control states at one point on the pressure differential/flow profile can be extrapolated to the rest of the profile when the comparisons have been made at the same flow. 4. True catecholamines cause a maximum 60% decrease in vascular resistance (at the same flow) by stimulation of β1-adrenergic receptors in the gills. 5. Branchial dimensions and perfusate viscosities have been measured and, together with the pressure differential/flow data, have been used to evaluate the Muir-Brown model of vascular resistance in the teleost gill. The model, with some limitations, fits the present data and suggests that both active and passive resistance changes are best explained by alterations in the number of secondary lamellae perfused.

Angiotensin extraction by trout tissues in vivo and metabolism by the perfused gill

1986 ◽  
Vol 250 (3) ◽  
pp. R532-R538 ◽  
Author(s):  
K. R. Olson ◽  
D. Kullman ◽  
A. J. Narkates ◽  
S. Oparil
Keyword(s):  
Plasma Catecholamines ◽  
Gill Tissue ◽  
Salmo Gairdneri ◽  
Cell Contact ◽  
Ang Ii ◽  
Angiotensin I ◽  
Respiratory Pathway ◽  
In Series ◽  
Mammalian Lung

Plasma clearance and tissue accumulation of 125I-angiotensin I, [Asp1, Ile5]ANG I, and [14C]sucrose, an inert volume reference, were measured after a bolus injection into the dorsal aorta of rainbow trout, Salmo gairdneri. Retention and metabolism of ANG I to angiotensin II (ANG II) and their constituent 1-4 peptide by the gill were examined using an isolated perfused arch preparation in which outflow from the respiratory and central filamental (venous) pathways was separated. Clearance of ANG I from plasma is multiexponential, reflecting dilution and tissue extraction. Liver, bile, gonads, corpuscles of Stannius, and white skeletal muscle accumulate more 125I than 14C; gill tissue accumulates less 125I than 14C. ANG I and II are retained by the perfused gill longer than the inert vascular marker sucrose, even though the distribution volumes of the former are less. The gill respiratory pathway converts ANG I to ANG II whereas the venous pathway metabolizes either ANG I or II to the 1-4 peptide and other metabolites. The gill respiratory pathway is in series with the systemic vasculature, has a large blood-cell contact area, and, like the mammalian lung, is ideally suited to activate ANG I. The gill venous pathway is in parallel with the systemic vasculature and removes ANG II from the circulation. During stress, elevated plasma catecholamines may reduce venous perfusion and thereby help maintain elevated circulating ANG II levels through reduced venous metabolism.

scholarly journals Cadmium inhibition of Ca2+ uptake in rainbow trout gills

1987 ◽  
Vol 253 (2) ◽  
pp. R216-R221 ◽  
Author(s):  
P. M. Verbost ◽  
G. Flik ◽  
R. A. Lock ◽  
S. E. Wendelaar Bonga
Keyword(s):  
Rainbow Trout ◽  
Inhibitory Action ◽  
Gill Tissue ◽  
Salmo Gairdneri ◽  
Gill Epithelium ◽  
In Vitro Exposure ◽  
Ca2 Channels ◽  
Tight Epithelium

The effects of cadmium (Cd2+) on calcium (Ca2+) transport in the gills of rainbow trout (Salmo gairdneri) were studied. The gill epithelium of freshwater fish represents a model for a Ca2+-transporting tight epithelium. Unidirectional Ca2+ fluxes in the gills were estimated in an isolated saline-perfused head preparation. Ca2+ influx was not affected when up to 10 microM Cd were added to the ventilatory water at the start of flux determinations (in vitro exposure). However, after 16 h in vivo preexposure of the fish to 0.1 microM Cd in the water, a 79% inhibition of Ca2+ influx was observed. Ca2+ efflux was not affected when up to 10 microM Cd were added to the ventilatory water during the flux determination. Ca2+ efflux in fish preexposed to 0.1 microM Cd for 16 h was also not affected; a preexposure to 1 microM Cd, however, resulted in a 173% increase in Ca2+ efflux rates. Tracer retention in the gill tissue indicated that both Ca2+ and Cd2+ enter the gill epithelium via a lanthanum (La3+)-inhibitable pathway. It is concluded that Cd2+ readily enters the branchial epithelial cells, similarly as Ca2+ does via La3+-sensitive apical Ca2+ channels. The inhibitory action of Cd2+ on transepithelial Ca2+ influx seems to result from an inhibition of the basolateral Ca2+ transport, occurring after a critical intracellular Cd2+ concentration has been reached.

Methylprednisolone on circulating eicosanoids and vasomotor tone after endotoxin

1986 ◽  
Vol 61 (1) ◽  
pp. 185-191 ◽  
Author(s):  
C. A. Hales ◽  
R. D. Brandstetter ◽  
C. F. Neely ◽  
M. B. Peterson ◽  
D. Kong ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Vascular Resistance ◽  
Systemic Blood Pressure ◽  
Physiological Effect ◽  
High Dose ◽  
Systemic Blood ◽  
Eicosanoid Production ◽  
Circulating Levels

Acute pulmonary and systemic vasomotor changes induced by endotoxin in dogs have been related, at least in part, to the production of eicosanoids such as the vasoconstrictor thromboxane and the vasodilator prostacyclin. Steroids in high doses, in vitro, inhibit activation of phospholipase A2 and prevent fatty acid release from cell membranes to enter the arachidonic acid cascade. We, therefore, administered methylprednisolone (40 mg/kg) to dogs to see if eicosanoid production and the ensuing vasomotor changes could be prevented after administration of 150 micrograms/kg of endotoxin. The stable metabolites of thromboxane B2 (TxB2) and 6-ketoprostaglandin F1 alpha (6-keto-PGF1 alpha) were measured by radioimmunoassay. Methylprednisolone by itself did not alter circulating eicosanoids but when given 2.5 h before endotoxin not only failed to inhibit endotoxin-induced eicosanoid production but actually resulted in higher circulating levels of 6-keto-PGF1 alpha (P less than 0.05) compared with animals receiving endotoxin alone. Indomethacin prevented the steroid-enhanced concentrations of 6-keto-PGF1 alpha after endotoxin and prevented the greater fall (P less than 0.05) in systemic blood pressure and systemic vascular resistance with steroid plus endotoxin than occurred with endotoxin alone. Administration of methylprednisolone immediately before endotoxin resulted in enhanced levels (P less than 0.05) of both TxB2 and 6-keto-PGF1 alpha but with a fall in systemic blood pressure and vascular resistance similar to the animals pretreated by 2.5 h. In contrast to the early steroid group in which all of the hypotensive effect was due to eicosanoids, in the latter group steroids had an additional nonspecific effect. Thus, in vivo, high-dose steroids did not prevent endotoxin-induced increases in eicosanoids but actually increased circulating levels of TxB2 and 6-keto-PGF1 alpha with a physiological effect favoring vasodilation.

Comparaison des échanges branchiaux de Cl− en eau douce chez Salmo gairdneri in vivo et in vitro sur la tête isolée perfusée

1978 ◽  
Vol 35 (4) ◽  
pp. 477-479 ◽  
Author(s):  
P. Payan ◽  
P. Pic ◽  
G. De Renzis
Keyword(s):  
Salmo Gairdneri ◽  
Net Uptake

The Cl− influxes are identical in vivo and in vitro providing that the gills are externally irrigated during the preparation of the isolated head. A net uptake of Cl− is observed. When no irrigation is used the Cl− influx is reduced by 66% and Cl− is lost by the preparation.

Effects of epinephrine on branchial non-electrolyte permeability in rainbow trout

1978 ◽  
Vol 74 (1) ◽  
pp. 227-237 ◽  
Author(s):  
J. Isaia ◽  
J. Maetz ◽  
G. P. Haywood
Keyword(s):  
Rainbow Trout ◽  
Beta Blocker ◽  
Transport Mechanism ◽  
Constant Pressure ◽  
Salmo Gairdneri ◽  
Permeability Coefficients ◽  
Lipophilic Substance ◽  
Hydrophilic Solutes ◽  
Bulk Transport

Using isolated heads perfused at constant pressure, at rates close to those occurring in vivo, the permeability of the gills of the trout Salmo gairdneri to a range of solutes was measured. Under epinephrine-free conditions, butanol and water showed similar high branchial permeability coefficients. Urea, inulin and dextrans (mol. wt 3000 and 20 000) were 7–12 times less permeant, and mannitol 60-70 times less permeant than water or butanol. Epinephrine, at 10(−6) M, greatly increased the permeability of the gills to the small hydrophilic molecules, water and urea, and to the lipophilic substance, butanol, but did not affect the penetration of the large hydrophilic solutes, mannitol, inulin and dextrans. In the presence of 10(−6) M propanolol, a beta-blocker, epinephrine had no effect on the permeation of any of the test substances except that the permeability to urea decreased somewhat. The results suggest that epinephrine increases the permeability of the membranes of the branchial cells but does not affect the permeation of substances that cross the gill walls by paracellular routes or via an intracellular ‘bulk-transport’ mechanism. Such an action would be expected to increase the branchial transfer of oxygen.

Use of pulse pressure method for estimating total arterial compliance in vivo

1999 ◽  
Vol 276 (2) ◽  
pp. H424-H428 ◽  
Author(s):  
N. Stergiopulos ◽  
P. Segers ◽  
N. Westerhof
Keyword(s):  
Pulse Pressure ◽  
Diastolic Pressure ◽  
Arterial Compliance ◽  
Aortic Pressure ◽  
Lower Limbs ◽  
Pressure Method ◽  
Total Arterial Compliance ◽  
The Difference ◽  
Pulse Pressure Method

We determined total arterial compliance from pressure and flow in the ascending aorta of seven anesthetized dogs using the pulse pressure method (PPM) and the decay time method (DTM). Compliance was determined under control and during occlusion of the aorta at four different locations (iliac, renal, diaphragm, and proximal descending thoracic aorta). Compliance of PPM gave consistently lower values (0.893 ± 0.015) compared with the compliance of DTM (means ± SE; r = 0.989). The lower compliance estimates by the PPM can be attributed to the difference in mean pressures at which compliance is determined (mean pressure, 81.0 ± 3.6 mmHg; mean diastolic pressure, over which the DTM applies, 67.0 ± 3.6 mmHg). Total arterial compliance under control conditions was 0.169 ± 0.007 ml/mmHg. Compliance of the proximal aorta, obtained during occlusion of the proximal descending aorta, was 0.100 ± 0.007 ml/mmHg. Mean aortic pressure was 80.4 ± 3.6 mmHg during control and 102 ± 7.7 mmHg during proximal descending aortic occlusion. From these results and assuming that upper limbs and the head contribute as little as the lower limbs, we conclude that 60% of total arterial compliance resides in the proximal aorta. When we take into account the inverse relationship between pressure and compliance, the contribution of the proximal aorta to the total arterial compliance is even more significant.

Characterization of branchial transepithelial calcium fluxes in freshwater trout, Salmo gairdneri

1988 ◽  
Vol 254 (3) ◽  
pp. R491-R498 ◽  
Author(s):  
S. F. Perry ◽  
G. Flik
Keyword(s):  
Active Transport ◽  
Calcium Uptake ◽  
Chloride Cells ◽  
Salmo Gairdneri ◽  
Apical Surface ◽  
Electrochemical Gradient ◽  
Plasma Membrane Vesicles ◽  
Pavement Cells ◽  
Calcium Fluxes

Experiments were performed to determine whether gill transepithelial calcium fluxes in the freshwater trout (Salmo gairdneri) are passive or require active transport and to characterize the mechanisms involved. A comparison of the in vivo unidirectional flux ratios with the flux ratios calculated according to the transepithelial electrochemical gradients revealed that calcium uptake from the water requires active transport of Ca2+. The inhibition of calcium uptake by external lanthanum, the specific deposition of lanthanum on the apical surface of chloride cells, and the favorable electrochemical gradient for calcium across the apical membrane suggest that the initial step in branchial calcium uptake is the passive entry of calcium into the cytosol of chloride cells through apical channels that are permeable to calcium. The study of gill basolateral plasma membrane vesicles demonstrated the existence of a high-affinity calmodulin-dependent calcium-transporting system [half-maximal Ca2+ concentration (K0.5) = 160 nM, Vmax = 1.86 nmol.min-1.mg protein-1]. This system actively transports calcium from the cytosol of chloride cells into the plasma against a sizeable electrochemical gradient, thereby completing the transepithelial uptake of calcium. Calcium efflux occurs passively through paracellular pathways between chloride cells and adjacent pavement cells or between neighboring pavement cells.

Comparison of indirect calorimetry and a new breath 13C/12C ratio method during strenuous exercise

1992 ◽  
Vol 263 (1) ◽  
pp. E64-E71 ◽  
Author(s):  
J. A. Romijn ◽  
E. F. Coyle ◽  
J. Hibbert ◽  
R. R. Wolfe
Keyword(s):  
Indirect Calorimetry ◽  
Fat Oxidation ◽  
Substrate Oxidation ◽  
Co2 Production ◽  
Strenuous Exercise ◽  
Ratio Method ◽  
O2 Uptake ◽  
Underlying Assumption ◽  
Oxidation Rates

A new stable isotope method for the determination of substrate oxidation rates in vivo is described and compared with indirect calorimetry at rest and during high-intensity exercise (30 min at 80-85% maximal O2 uptake capacity) in six well-trained cyclists. This method uses the absolute ratios of 13C/12C in expired air, endogenous glucose, fat, and protein in addition to O2 consumption and is independent of CO2 production (VCO2). Carbohydrate and fat oxidation rates at rest, calculated by both methods, were not significantly different. During exercise the breath 13C/12C ratio increased and reached a steady state after 15-20 min. Carbohydrate oxidation rates during exercise were 39.4 +/- 5.2 and 41.7 +/- 5.7 mg.kg-1.min-1 [not significant (NS)], and fat oxidation rates were 7.3 +/- 1.3 and 6.9 +/- 1.2 mg.kg-1.min-1 (NS), using indirect calorimetry, and the breath ratio method, respectively. We conclude that the breath 13C/12C ratio method can be used to calculate substrate oxidation under different conditions, such as the basal state and exercise. In addition, the results obtained by this new method support the validity of the underlying assumption that indirect calorimetry regards VCO2 as a reflection of tissue CO2 production, during exercise in trained subjects, even up to 80-85% maximal O2 uptake.

Sign in / Sign up

Export Citation Format

Share Document