The preparation of the in situ heart was accomplished without any physical disturbance to the heart. The heart generated an intrinsic rhythm which was steady throughout the experiment and apparently was derived from the sinoatrial pacemaker. The power output developed by the in situ heart at physiological preloads and after loads was comparable to in vivo values. The effect of increasing preload (0 to 3 cmH2O) was a fourfold increase in stroke volume with little or no change in heart rate. When after load was changed (25 to 45 cmH2O) heart rate was unchanged and stroke volume was usually maintained. As a consequence, cardiac output was maintained by intrinsic factors alone at a higher work load. Epinephrine (10−9 to 10−5 M) in the perfusate produced relatively weak positive chronotropic and inotropic effects. The increase in cardiac output produced by epinephrine was small compared with the intrinsic changes evoked when preload was raised.

The calculability of synchrotron radiation (SR) makes electron storage rings wonderful light sources for radiometry. The broadband nature of SR allows coverage of the entire spectral region from the X-ray to the far-infrared. Compact low-energy storage rings like the Synchrotron Ultraviolet Radiation Facility SURF III are perfect sources for radiometric applications, because the output spectrum can be custom-tailored to the user's needs: low current operations can simulate the solar spectrum, changes to the electron energy can address higher-order contributions of spectrometers and monochromators, and manipulation of the source size can increase the lifetime or change the radiation density. At large multi-user facilities these special operational conditions are generally not possible, since many users have to be satisfied simultaneously. At SURF III, NIST maintains one of the best SR-based infrared to soft X-ray calibration programs in the world: standard lamp calibrations, detector calibrations, and measurements of optical properties are routinely performed at SURF with great reliability and accuracy.

Juvenile pink salmon (Oncorhynchus gorbuscha (Walbaum, 1792)) enter seawater (SW) shortly following emergence. Little is known about growth and development during this life-history stage when sensitivity to sea louse exposure may be high, an issue that is of current concern in British Columbia. We tested the hypothesis that growth and ionoregulatory development were similar in hatchery-raised (Quinsam) and wild (Glendale and One's Point) juvenile pink salmon (measured over 22 weeks) following SW entry. Fish body mass increased from 0.20 +/- 0.01 to 6.47 +/- 0.37 g, with mean specific growth rates of 2.74% to 3.05% body mass.day(-1) among the three groups. In all three groups, gill Na+-K+-ATPase (NKA) activity peaked at 12 mu mol ADP.mg protein(-1).h(-1) following 8 weeks post-transfer to SW. Whole body Na+ and Cl- concentrations, which again did not differ among groups, were highest upon initial exposure to SW (similar to 70 mmol.kg wet mass(-1)) and declined over time as gill NKA activity increased, indicating that the hypo-osmoregulatory capacity was not fully developed following emergence and initial entry into SW. Thus, consistent with our hypothesis, few differences were observed between hatchery-raised and wild juvenile pink salmon reared under laboratory conditions. These baseline data may be important for future studies in determining the effects of sea lice on wild juvenile pink salmon.

The National Institute of Standards and Technology (NIST) has operated the Synchrotron Ultraviolet Radiation Facility (SURF) continuously since the early 1960s. The original accelerator was converted into a storage ring, called SURF II, in 1974. Then in 1998, motivated mainly by limitations in the accuracy of radiometric calibrations and the wish to extend the spectrum of the emitted synchrotron radiation to shorter wavelengths, a second major upgrade was performed. This time the whole magnet system was replaced to improve the calculability and allow for higher magnetic fields. Since the recommissioning of SURF III we have been working to improve the stability of the stored electron beam through modifications of the radio-frequency system, leading to operations with unprecedented stability and new record injection currents topping 700 mA.

The lethality, anaesthetic and physiological effects of ‘pulsed’ cyanide (CN-) exposures to a common tropical marine fish Dascyllus aruanus were assessed. Cyanide (25 and 50 mg l-1) was applied as pulses (10, 60 and 120 s) to fish under non-stressed and stressed (by chasing and/or placing fish under hypoxic stress) conditions. Following treatment, the time until recovery and the percent survival were determined. The fish were allowed a 2.5 week recovery period from the treatments at which time four physiological end-points were measured: (1) the blood haemoglobin content, (2) the percent blood O-2 content, (3) the liver rhodonase activity and (4) the liver O2 consumption rate. The greater the CN- concentration and exposure time, the longer the recovery time. Non-stressed fish exposed to 10 s pulses of 25 mg l-1 of CN- fully recovered within 4 min whereas fish exposed for 60 s and 50 mg l-1 of CN- required up to 50 min for full recovery. Exposure for 120 s at 25 and 50 mg l-1 of CN- proved lethal. Under stressed conditions, previously non-lethal exposures (60 s and 50 mg l-1) were lethal. Of the physiological end-points, only the liver O2 consumption rate was indicative of previous CN- exposure. Under non-stressed conditions, pulsed exposures at 25 and 50 mg l-1 of CN- for 10 and 60 s significantly reduced the liver O2 consumption rates (ANOVA; p < 0.05). Under stressed conditions, the liver O2 consumption rates were significantly greater (maximum rates up to 17-fold greater) than the control fish (ANOVA; p < 0.05). We conclude, therefore, that environmentally relevant exposures of CN- can adversely effect fish and this affect can be measured 2.5 weeks post-exposure. Importantly, the combined effects of exposure and stress both increased the mortality and placed an appreciable metabolic load on the fish as indicated by the elevated liver O2 consumption rates. Handling stress in combination with anaesthetic CN- doses could in part explain the delayed mortality reportedly associated with CN- use in the tropical fish trade. The significance of the elevated liver O2 consumption rates on the survival of CN--exposed fish is unknown

This study surveyed and compared vasoactive responses of isolated coronary vessels from steelhead trout (Oncorhynchus mykiss), rainbow trout (also O. mykiss), and spiny dogfish (Squalus acanthias). The purpose of the investigation was twofold: to identify vasoactive controls that were possibly mediated by the vascular endothelium and to highlight the possible consequences on vasoactivity of the coronary lesions known to be present in the main coronary of salmonids but not dogfish. The test substances included acetylcholine, adenosine, adenosine triphosphate, adenosine diphosphate, serotonin, thrombin, bradykinin, prostaglandin F2α, prostaglandin I2, prostaglandin E2, and the fatty acids arachidonic acid, docosahexaenoic acid, and eicosapentaenoic acid. Acetylcholine, adenosine, adenosine triphosphate, adenosine diphosphate and prostaglandin F2αtypically produced contractions. Use of endothelial removal techniques and antagonists failed to reveal any relaxations that might involve the endothelium. Thrombin and bradykinin had no vasoactivity. Serotonin, prostaglandin I2, and prostaglandin E2produced relaxations that were not mediated by the endothelium. The powerful relaxations observed with prostaglandin I2and prostaglandin E2and the powerful contractions observed with prostaglandin F2αsuggest a major role of prostanoids in coronary vasoactivity in fish. These prostanoid-mediated mechanisms, in addition to the previously demonstrated powerful contractions with endothelin-1, point to an important role for the endothelium. No major qualitative or quantitative differences in vasoactivity could be related to differences in coronary lesion severity.

Development of coronary arteriosclerosis has been studied in all life stages of both wild and cultured Atlantic salmon (Salmo salar). Lesions accumulate slowly during juvenile growth in freshwater in both wild and cultured populations and increase sharply during early marine life; much of the progression occurs well before the onset of sexual maturity. Fewer than 5% of sexually mature Atlantic salmon (wild or fast-growing cultivated) were free of coronary lesions. Lesions were distributed over 45–85% of the length of the coronary artery. Lesions were less abundant and less advanced in a cultured strain of salmon that grew more slowly than another cultured, fast-growing strain. We conclude that prevalence and severity of lesions in Atlantic salmon accelerate in parallel with, and possibly in response to, those factors responsible for rapid growth in the sea. We discuss diet, endocrine changes associated with sexual maturation, metabolic aspects of parr–smolt transformation, and physiological stress as factors possibly influencing progression of lesions associated with rapid growth during the marine stage.

ABSTRACT Myocardial oxygen consumption was measured using an in situ, perfused heart preparation at 10°C increased in a linear fashion with power output when cardiac output was elevated (volume loading). The increased was possible through improved O2 delivery , but was reduced. The mechanical efficiency of the heart was improved. also increased in a linear fashion with power output when output pressure was increased with constant (pressure loading). The increased was supported by increased O2 removal from the perfusate since oxygen delivery was constant. Once more, improved mechanical efficiency was observed. decreased as O2 delivery was reduced with progressive hypoxia. Even so, power output was maintained at a perfusate input of 81 Torr. Five of 11 hearts survived a 30-Torr exposure, but with a 29 % decrease in power output and a 5-fold reduction in . The increase in the apparent aerobic efficiency which enabled this is discussed.

The effect of extracellular calcium ([Ca2+]e) on the performance of the in situ perfused sea raven heart was evaluated under nonacidotic, acidotic, and high work load conditions. Increases in [Ca2+]e improved power output of the nonacidotic heart and restored control levels of power output to the heart exposed to hypercapnic acidosis (1.8% CO2, pH 7.4). Extracellular acidosis severely curtailed the scope for cardiac work (increased cardiac output and afterload), and only a 50% increase in the control, nonacidotic power output was possible with increases in preload and saturating levels of [Formula: see text]. It is suggested that increases in preload are probably more important than increases in [Ca2+]e to improve cardiac performance in the seas raven heart during extracellular acidosis.

Specific sections describe the intrinsic properties of the heart, myocardial oxygen uptake, and the effects on cardiac performance of circulating catecholamines, acidosis, hypoxia, and temperature. Stroke volume (SV H ) is primarily regulated by preload of the heart and heart rate (f H ) (Frank–Starling effect). Routine variations in cardiac performance are probably accommodated by the intrinsic ability to increase cardiac output [Formula: see text] in response to preload and to maintain [Formula: see text] constant over a range of "afterloads" (homeometric regulation). The sinoatrial pacemaker governs f H and its frequency is altered primarily by temperature and vagal inhibition, secondarily by circulating catecholamines or adrenergic innervation, and probably not at all by preload or afterload in teleosts. Venous blood provides an ample myocardial O 2 supply in benthic fishes. In more active fish, a coronary circulation and myocardial myoglobin are also important in O 2 delivery. It is suggested that circulating catecholamines protect and maintain cardiac performance during stressful situations (e.g., hypoxia and acidosis) rather than to increase SV H per se. Lastly, temperature adaptations involve changes in SV H , f H and [Formula: see text].

The physiological integrity of the in situ perfused heart of the ocean pout was established by its ability to maintain cardiac output (Q) over a range of work loads, and by the dependence of Q upon the filling pressure of the heart. Similar observations have been reported previously for the in situ perfused heart of the sea raven. Physiological levels of extracellular acidosis (pH 7.6/1% CO2 and pH 7.4/2% CO2) significantly depressed cardiac performance in sea raven and ocean pout hearts in situ. Negative chronotropic and inotropic responses were observed. Adrenaline (AD; 10(-7) M) under control conditions (pH 7.9/0.5% CO2) produced a sustained tachycardia. The tachycardia reduced filling time of the ventricle and stroke volume was compromised because of the constant preload to the heart. Consequently, AD produced only an initial, transient increase in stroke volume and Q. Thereafter, stroke volume was reduced in proportion with the increase in heart rate, and Q remained unchanged. The combined challenge of extracellular acidosis and AD demonstrated interactive effects between AD and acidosis in situ. Q and power output were maintained in both species at both levels of extracellular acidosis during the combined challenge. Thus AD alone can maintain (but not improve upon) basal Q during extracellular acidosis. The effects of extracellular acidosis, circulating catecholamines and venous return pressure to the heart are discussed in relation to the regulation of Q following exhaustive exercise.

1.1. Total cholesterol and high density lipids (HDL) were measured in the blood of Atlantic salmon (Salmo salar), brook trout (Salvelinus fontinalis) and rainbow trout (Salmo gairdneri) from a variety of dietary and environmental regimes.2.2. At spawning the total cholesterol of cage reared S. salar was high compared to sea ranched S. salar.3.3. Starvation of S. salar in freshwater for 6–11 months depressed total blood cholesterol levels, but not to unusually low levels.4.4. A cholesterol supplement of 0.02 g/100 g body weight to a chow diet of 0.38g/100g body weight had no significant effect on the total blood cholesterol level in Salvelinus fontinalis.5.5. The high proportion of HDL in the blood of S. salar is discussed in terms of its possible importance during the atherosclerotic lesion formation that normally accompanies spawning in these salmon.

AbstractDynamic intravascular pressures were measured in the afferent and efferent filament arteries of Ophiodon elongatus using micropipettes. Measurements from anesthetized fish and from isolated, saline‐perfused preparations indicated that the major site of gill resistance was located in the lamellar complex (secondary lamella and associated arterioles). The presence of a postlamellar cholinergic constrictor site was also supported by efferent arterial pressure measurements during acetylcholine administration.

The morphology, morphometric relationships, and vascular geometry were established for ling cod gills using fixed tissue and vascular casts. Calculations using Poiseuillian and sheet flow equations permitted predictions of the resistance and the pressure drop in various vessels of the respiratory network in the gill filament. It was found that the afferent lamellar arteriole was the major vascular resistance. Blood transit times through the gills were also calculated and discussed.