Seasonal temperature acclimatisation of rainbow trout: cardiovascular and morphometric influences on maximal sustainable exercise level

1996 ◽  
Vol 199 (4) ◽  
pp. 835-845 ◽  
Author(s):  
S Taylor ◽  
S Egginton ◽  
E Taylor
Keyword(s):  
Blood Flow ◽  
Rainbow Trout ◽  
Aerobic Exercise ◽  
Stride Length ◽  
Regional Blood Flow ◽  
Swimming Performance ◽  
Beat Frequency ◽  
Slow Muscle ◽  
Seasonal Temperature ◽  
Arterial Blood

Adult rainbow trout (mass 600-1500 g; length 40-44 cm) were held in the laboratory for up to 28 days at seasonally appropriate temperatures. The maximal sustainable aerobic exercise level (involving slow-twitch muscle activity alone) was determined by following muscle recruitment patterns using electromyography. The mean (± s.e.m.) speeds recorded for maximal sustainable aerobic exercise were 0.52±0.02, 0.81±0.06 and 0.39±0.02 BL s-1 (body lengths per second) for animals swimming at their acclimatisation temperatures of 4, 11 and 18 °C, respectively. Thus, fish acclimatised to 11 °C reached the highest maximal sustainable (purely aerobic) levels of exercise. They had similar stride lengths to the 4 °C animals, but generated less thrust per stride, as indicated by increased tail-beat frequency. Acclimatisation to 4 °C led to an increased mass of slow muscle and more effective tail beats (greater stride length at lower frequencies), relative to animals at higher temperatures. Fish acclimatised to 18 °C had the lowest stride length and a reduced aerobic swimming capacity. Sustainable levels of aerobic exercise were reflected in unchanged values for mean heart rate and arterial blood pressure between rest and imposed, graded exercise. Radiolabelled microspheres were used to determine cardiac output (V.b) and regional blood flow distribution simultaneously in fish, both at rest and while swimming, for each acclimatisation temperature. Fish acclimatised to 11 °C had the greatest scope for increasing V.b. This resulted in a significant hyperaemia in slow muscle upon exercise (10-fold increase), without an active redistribution of flow from other tissues. Maximum V.b at 18 °C did not differ significantly from that at 11 °C but, because resting V.b was higher, the scope was reduced and was similar to that found at 4 °C. Specific blood flow to the active muscle was also reduced and this, together with decreased blood oxygen content and reduced slow muscle mass, may limit aerobic swimming performance at 18 °C.

ASSESSMENT OF MAXIMUM SUSTAINABLE SWIMMING PERFORMANCE IN RAINBOW TROUT (ONCORHYNCHUS MYKISS)

1994 ◽  
Vol 192 (1) ◽  
pp. 299-305 ◽  
Author(s):  
R Wilson ◽  
S Egginton
Keyword(s):  
Rainbow Trout ◽  
Aerobic Exercise ◽  
White Muscle ◽  
Swimming Performance ◽  
Blood Chemistry ◽  
Laboratory Method ◽  
Muscle Fibres ◽  
Seasonal Temperature ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Cardiovascular Performance

Levels of swimming activity in fishes have been divided into three categories on the basis of the time a given speed can be maintained before the onset of fatigue (Beamish, 1978): sustained (more than 200 min), prolonged (20 s to 200 min) and burst swimming (less than 20 s). The locomotory capacity of a given species reflects both its lifestyle and its body form, although definitions of performance may vary. It is generally accepted that only the aerobic ('red') muscle fibres should be active at truly sustainable swimming speeds, i.e. at speeds that can be maintained indefinitely without fatigue. However, the standard laboratory method of evaluating the maximum sustainable swimming speed (Ucrit; Brett, 1964) almost certainly entails the recruitment of at least some of the rapidly fatigable fast glycolytic ('white') fibres at sub-critical speeds and undoubtedly complicates the evaluation of maximal cardiovascular performance. It would therefore be useful to have an objective and reproducible measure of truly sustainable performance that, by definition, relies solely on aerobic muscle activity. Electromyography (EMG) has been used to examine the pattern of white muscle recruitment following thermal acclimation in striped bass, Morine saxatilis (Sisson and Sidell, 1987). We wished to incorporate this method into a study of the acclimatory responses to chronic changes in environmental temperature of the cardiovascular and locomotory systems in rainbow trout (Wilson and Egginton, 1992). The present communication presents results on the cardiovascular performance and blood chemistry, at rest and during maximal aerobic exercise, of rainbow trout acclimated to 11 °C, as a validation of the methodology currently in use with fish acclimated to seasonal temperature extremes (Taylor et al. 1992). Different acclimation temperatures are known to produce compensatory changes in the relative proportions of red and white muscle mass (Sidell and Moerland, 1989). The aim of these continuing investigations is to compare the anatomical, cardiovascular and locomotory limitations to aerobic exercise over the full temperature range of a eurythermal fish species.

Regional blood flow in the brain and spinal cord of hypothermic rats

1989 ◽  
Vol 257 (3) ◽  
pp. H785-H790
Author(s):  
T. Sakamoto ◽  
W. W. Monafo
Keyword(s):  
Spinal Cord ◽  
Blood Flow ◽  
Brain Stem ◽  
Regional Blood Flow ◽  
Experimental Conditions ◽  
Pentobarbital Sodium ◽  
Arterial Blood ◽  
Group A ◽  
Group B ◽  
The Brain

[14C]butanol tissue uptake was used to measure simultaneously regional blood flow in three regions of the brain (cerebral and cerebellar hemispheres and brain stem) and in five levels of the spinal cord in 10 normothermic rats (group A) and in 10 rats in which rectal temperature had been lowered to 27.7 +/- 0.3 degrees C by applying ice to the torso (group B). Pentobarbital sodium anesthesia was used. Mean arterial blood pressure varied minimally between groups as did arterial pH, PO2, and PCO2. In group A, regional spinal cord blood flow (rSCBF) varied from 49.7 +/- 1.6 to 62.6 +/- 2.1 ml.min-1.100 g-1; in brain, regional blood flow (rBBF) averaged 74.4 +/- 2.3 ml.min-1.100 g-1 in the whole brain and was highest in the brain stem. rSCBF in group B was elevated in all levels of the cord by 21-34% (P less than 0.05). rBBF, however, was lowered by 21% in the cerebral hemispheres (P less than 0.001) and by 14% in the brain as a whole (P less than 0.05). The changes in calculated vascular resistance tended to be inversely related to blood flow in all tissues. We conclude that rBBF is depressed in acutely hypothermic pentobarbital sodium-anesthetized rats, as has been noted before, but that rSCBF rises under these experimental conditions. The elevation of rSCBF in hypothermic rats confirms our previous observations.

Sexual dimorphism in regional blood flow responses to vasopressin in conscious rats

1997 ◽  
Vol 273 (3) ◽  
pp. R1126-R1131 ◽  
Author(s):  
Y. X. Wang ◽  
J. T. Crofton ◽  
S. L. Bealer ◽  
L. Share
Keyword(s):  
Blood Flow ◽  
Vascular Resistance ◽  
Regional Blood Flow ◽  
Pressor Response ◽  
Peripheral Resistance ◽  
Female Rats ◽  
Sexually Dimorphic ◽  
Arterial Blood ◽  
Vasoconstrictor Response ◽  
Renal Vascular

The greater pressor response to vasopressin in male than in nonestrous female rats results from a greater increase in total peripheral resistance in males. The present study was performed to identify the vascular beds that contribute to this difference. Mean arterial blood pressure (MABP) and changes in blood flow in the mesenteric and renal arteries and terminal aorta were measured in conscious male and nonestrous female rats 3 h after surgery. Graded intravenous infusions of vasopressin induced greater increases in MABP and mesenteric vascular resistance and a greater decrease in mesenteric blood flow in males. Vasopressin also increased renal vascular resistance to a greater extent in males. Because renal blood flow remained unchanged, this difference may be due to autoregulation. The vasopressin-induced reduction in blood flow and increased resistance in the hindquarters were moderate and did not differ between sexes. Thus the greater vasoconstrictor response to vasopressin in the mesenteric vascular bed of male than nonestrous females contributed importantly to the sexually dimorphic pressor response to vasopressin in these experiments.

Regional circulatory responses to hypocapnia and hypercapnia in bar-headed geese

1986 ◽  
Vol 250 (3) ◽  
pp. R499-R504 ◽  
Author(s):  
F. M. Faraci ◽  
M. R. Fedde
Keyword(s):  
Blood Flow ◽  
Regional Blood Flow ◽  
Muscle Blood Flow ◽  
Pectoral Muscle ◽  
Blood Flows ◽  
Arterial Blood ◽  
Blood Flow Reduction ◽  
Extreme Altitude ◽  
Anser Indicus ◽  
O2 Delivery

To investigate mechanisms that may allow birds to tolerate extreme high altitude (hypocapnic hypoxia), we examined the effects of severe hypocapnia and moderate hypercapnia on regional blood flow in bar-headed geese (Anser indicus), a species that flies at altitudes up to 9,000 m. Cerebral, coronary, and pectoral muscle blood flows were measured using radioactive microspheres, while arterial CO2 tension (PaCO2) was varied from 7 to 62 Torr in awake normoxic birds. Arterial blood pressure was not affected by hypocapnia but increased slightly during hypercapnia. Heart rate did not change during alterations in PaCO2. Severe hypocapnia did not significantly alter cerebral, coronary, or pectoral muscle blood flow. Hypercapnia markedly increased cerebral and coronary blood flow, but pectoral muscle blood flow was unaffected. The lack of a blood flow reduction during severe hypocapnia may represent an important adaptation in these birds, enabling them to increase O2 delivery to the heart and brain at extreme altitude despite the presence of a very low PaCO2.

Discrepancy between microsphere and diffusible tracer estimates of perfusion to ischemic myocardium

1985 ◽  
Vol 249 (2) ◽  
pp. H255-H264 ◽  
Author(s):  
S. Yoshida ◽  
S. Akizuki ◽  
D. Gowski ◽  
J. M. Downey
Keyword(s):  
Blood Flow ◽  
Coronary Artery ◽  
Regional Blood Flow ◽  
Distal Segment ◽  
Ischemic Myocardium ◽  
Flow Diversion ◽  
Retrograde Flow ◽  
Arterial Blood ◽  
Zero Flow ◽  
133Xe Washout

This study critically tests the ability of microspheres to accurately measure perfusion to ischemic myocardium. The left anterior descending coronary artery was cannulated and perfused with arterial blood. The perfusion line was clamped, and a sidearm between the clamp and the cannula was opened to the atmosphere, allowing blood to flow retrograde from the distal segment of the artery. Measurement of regional blood flow during retrograde flow diversion with 15-micron microspheres revealed essentially zero flow to the perfused segment (0.005 ml X min-1 X g-1). Measurements under the same conditions by either 86Rb uptake or 133Xe washout revealed that an appreciable perfusion of the tissue persisted during retrograde flow diversion (0.043 and 0.11 ml X min-1 X g-1, respectively, for the 2 methods). Thus we have identified a condition during which microspheres indicate zero flow to the tissue but diffusible tracers can both be washed in and washed out at a brisk rate. We conclude that with simple occlusion there is a hidden component of perfusion to an ischemic zone that cannot be measured by microspheres, causing them to underestimate flow by about 25% in that condition.

Effects of oxygen on regional hemodynamics in hemorrhagic shock

1996 ◽  
Vol 271 (1) ◽  
pp. H203-H211 ◽  
Author(s):  
H. Bitterman ◽  
V. Brod ◽  
G. Weisz ◽  
D. Kushnir ◽  
N. Bitterman
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Hemorrhagic Shock ◽  
Vascular Resistance ◽  
Regional Blood Flow ◽  
Biceps Femoris ◽  
Total Blood ◽  
Biceps Femoris Muscle ◽  
Arterial Blood ◽  
Femoris Muscle

This study investigated mechanisms of the hemodynamic effects of oxygen in hemorrhagic shock induced by bleeding 30% of the total blood volume in anesthetized rats. An ultrasonic flowmeter was used to monitor regional blood flow. Changes in tissue perfusion were assessed by the laser-Doppler technique. The inhalation of 100% oxygen induced a significant increase in mean arterial blood pressure (MABP) and vascular resistance in the hindquarters, with a concomitant decrease in blood flow in the distal aorta and biceps femoris muscle. In contrast, oxygen did not change vascular resistance in the superior mesenteric artery (SMA) and renal beds and induced a significant increase in blood flow to the renal artery, SMA, and small bowel in hemorrhaged rats. L-Arginine (100 mg/kg iv) but not D-arginine or the vehicle (0.9% NaCl) completely abolished the effects of oxygen on blood pressure and reversed its effects on blood flow and resistance in the hindquarters and biceps femoris muscle. Administration of the nitric oxide (NO) synthase inhibitor NG-nitro-L-arginine methyl ester (50 mg/kg iv) significantly increased MABP and the resistance in the three vascular beds. Pretreatment of hemorrhaged rats with a superoxide dismutase mimic, the NO-stable radical 2,2,6,6-tetramethylpiperidine-N-oxyl (5 mg/kg iv), resulted in significantly diminished effects of oxygen on hindquarter hemodynamics. These results demonstrate a differential effect of oxygen, which increases vascular resistance in the hindquarters without a significant effect in the splanchnic and renal beds, thus favoring an increase in splanchnic and renal perfusion. It is suggested that inactivation of NO by reactive oxygen species may underlie the effects of oxygen on hindquarter vascular tone during shock.

Age-related changes in regional blood flow in the rat

1985 ◽  
Vol 249 (3) ◽  
pp. H485-H491 ◽  
Author(s):  
R. F. Tuma ◽  
G. L. Irion ◽  
U. S. Vasthare ◽  
L. A. Heinel
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Cardiac Index ◽  
Regional Blood Flow ◽  
Adult Rats ◽  
Blood Flows ◽  
Arterial Blood ◽  
Anesthetized Rats ◽  
Regional Blood Flows ◽  
Central Hemodynamic

The purpose of this investigation was to characterize the changes in regional blood flow and central hemodynamic measures that occur in the rat as a result of the aging process. The isotope-labeled microsphere technique was used to measure cardiac output and regional blood flows in conscious and anesthetized adult (12 mo) and senescent (24 mo) Fischer 344 virgin female rats. No significant changes were observed in central hemodynamic measurements or regional blood flows in conscious rats with the exception of a 25% reduction in splenic blood flow. Pentobarbital anesthesia significantly reduced cardiac index and heart rate but elevated total peripheral resistance and mean arterial blood pressure. There was a decrease in blood flow to skeletal muscle, spleen, duodenum, stomach, and brain tissue samples and increased hepatic arterial blood flow in both age groups. The use of anesthesia caused a greater reduction in the cardiac index and brain blood flow in the senescent anesthetized rats than in the adult rats. Heart and kidney blood flows were decreased by anesthesia in the senescent rats but not in the adult rats. Skeletal muscle blood flow, however, was significantly greater in the senescent anesthetized rats than in the younger anesthetized animals. Although body weight and organ weights of the liver, spleen, kidneys, stomach, heart, and brain were significantly greater for the senescent rats, no differences could be demonstrated in tibial length or lean body mass.

Circulatory and Ventilatory Responses of Rainbow Trout (Salmo gairdneri) to Artificial Manipulation of Gill Surface Area

1971 ◽  
Vol 28 (10) ◽  
pp. 1609-1614 ◽  
Author(s):  
John C. Davis
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Rainbow Trout ◽  
Surface Area ◽  
Salmo Gairdneri ◽  
Ventilatory Responses ◽  
Arterial Blood ◽  
Gill Area ◽  
Gill Surface Area ◽  
The Brain

Reductions in surface area of the gill were artificially produced by ligating various gill arches and occluding their blood supply. Rainbow trout (Salmo gairdneri) responded to a 40–57% reduction in gill area, by increasing cardiac output and ventilation volume, and probably by redistributing blood within the remaining functional gill area. Fish with blood flow to gill arches one and three only, could maintain arterial PO2 at 90–100 mm Hg, whereas, in those with blood flow to arches three and four only, arterial PO2 fell to around 40 mm Hg. The presence of a chemoreceptor site for the regulation of arterial PO2 associated with the efferent blood vessels of arch number one is discussed. Such a receptor may be located in the pseudobranch or in the portion of the brain supplied with arterial blood from the first gill arch.

Effects of insulin-like growth factor-I and LR3IGF-I on regional blood flow in normal rats

1997 ◽  
Vol 155 (2) ◽  
pp. 351-358 ◽  
Author(s):  
CM Gillespie ◽  
AL Merkel ◽  
AA Martin
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Vascular Resistance ◽  
Regional Blood Flow ◽  
Arterial Blood ◽  
Cardiovascular Side Effects ◽  
Igf I ◽  
The Central Nervous System ◽  
The Brain ◽  
Infusion Period

Two studies were conducted to investigate the haemodynamic effects of IGF-I and its analogue LR3IGF-I in normal anaesthetised rats. Infusion of IGF-I intravenously, at a dose of 125 micrograms/kg/h, for 20 min in the first study resulted in renal blood flow being significantly elevated by 35% above baseline. Mean arterial blood pressure (MABP) at this IGF-I dose fell by 18% of baseline, with LR3IGF-I also causing a significant decline in MABP (by 15%) at the dose of 125 micrograms/kg/h. In the second study the intravenous administration of IGF-I or LR3IGF-I, at a dose of 125 micrograms/kg/h, over a period of 60 min, resulted in MABP being significantly lowered by 25% of baseline values. Regional blood flow rates were determined using radioactive microspheres, 15 microns in diameter, injected systemically at the end of the peptide infusion period. The gastrocnemius, a representative skeletal muscle, was the only vascular region to show a significant increase in blood flow after IGF-I (by 58%) or LR3IGF-1 (by 308%) infusion. Vascular resistance in the brain was significantly reduced after infusion of IGF-I (by 60%) or LR3IGF-I (by 48%) as compared with vehicle. Skeletal muscle vascular resistance was also reduced by IGF-I (by 41%) and more particularly by LR3IGF-I (by 77%) in comparison to vehicle. These alterations to vascular tone produced by IGF infusion may be related to the central nervous system and systemic cardiovascular side-effects that have been reported during IGF-I administration in humans.

On the Function of the White Muscles in Teleosts at Intermediate Swimming Speeds

1973 ◽  
Vol 58 (2) ◽  
pp. 509-522 ◽  
Author(s):  
RICHARD C. L. HUDSON
Keyword(s):  
Rainbow Trout ◽  
Linear Relationship ◽  
Muscle Mass ◽  
Swimming Performance ◽  
Beat Frequency ◽  
Salmo Gairdneri ◽  
Electrical Activities ◽  
Tail Beat ◽  
Increased Activity

1. The swimming performance of rainbow trout, Salmo gairdneri, and the electrical activities, recorded extracellularly, of its red and mosaic muscles have been studied at different swimming speeds. 2. A linear relationship was found between the specific velocity (body lengths/sec) and the frequency of tail beating at frequencies up to 5/sec. 3. The red muscles are active at all swimming speeds at which the fish swim by tail oscillations. Discharges from this muscle decrease in duration with frequency up to 3.5-5.0 beats/sec and then increase while the interburst interval decreases linearly with tail-beat frequency. 4. Mosaic muscle becomes active at 3.05-3.60 tail beats/sec and increases slightly with increasing frequency of tail oscillations. Greatly increased activity was recorded in response to struggling and rapid accelerations. 5. The white (mosaic) muscle mass of teleosts is concluded to be involved at intermediate swimming speeds and to be active at the higher range of cruising speeds.

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