This review examines selected areas of cardiovascular physiology where there have been impressive gains knowledge and indicates fertile for future research. Because arterial blood is usually fully saturated with oxygen, increasing cardiac output the only means transferring substantially more oxygen to tissues. Consequently, any behavioural or environmental change that alters uptake typically involves a in output, which fishes can amount threefold change. During exercise, not all necessarily...

Elevated summer river temperatures are associated with high in-river mortality in adult sockeye salmon (Oncorhynchus nerka) during their once-in-a-lifetime spawning migration up the Fraser River (British Columbia, Canada). However, mechanisms underlying decrease whole-animal performance and cardiorespiratory collapse above optimal for aerobic scope (T opt) remain elusive aquatic ectotherms. This is part because all relevant variables have rarely been measured directly simultaneously exercise...

Rainbow trout, Oncorhynchus mykiss, were exercise trained for 28–52 days. Trained fish 13% larger and swam 12% faster in an aerobic swimming test. Training induced cardiac growth that was isometric with body growth, since ventricle mass relative to constant. The proportions of compact spongy myocardia the also unchanged by training. had significantly higher levels citrate synthase, β-hydroxyacyl CoA dehydrogenase, hexokinase both myocardium. Ligation a 0.5- 1.0-cm section coronary artery...

Relative ventricular mass, percent compact myocardium, total protein, DNA content, and myocyte size were determined for rainbow trout, Salmo gairdneri, ranging in from 10 to 2000 g. Ventricular content increased linearly with body size. The protein ratio was reduced slightly over a 100-fold range of Myocyte heart However, the estimated 1.7-fold increase volume 10-fold weight incompatible corresponding protein. Since it is suggested that long-term cardiac growth trout involves both...

ABSTRACT A perfused rainbow trout heart was developed which generated its own intrinsic rate and a physiological power output. This preparation wàs used to examine the mechanical properties of heart, dose-response effects catecholamines extracellular calcium on these properties, during exposure acidotic conditions. The relatively pressure-insensitive range ventral aortic pressures. Preload exerted an important control over cardiac output through Starling response. Heart independent both...

The HemoCue haemoglobin analyser consistently overestimated concentration ([Hb]) in the blood of all fish species (sockeye salmon Oncorhynchus nerka , Chinook tshawytscha Pacific bluefin tuna Thunnus orientalis and chub mackerel Scomber japonicus ) by 22–50% (9·9–36·0 g l −1 over a [Hb] range 20–160 . systematic nature overestimation, however, allowed formulation an accurate calibration equation that can be used to correct values measured field studies.

Temperature tolerance and heart rates were compared among nine sockeye salmon (Oncorhynchus nerka (Walbaum in Artedi, 1792)) populations, whose eggs incubated at 10, 14, 16 °C before rearing all hatchlings a common temperature. Critical thermal maximum (CTmax) significantly differed populations temperature treatments. Populations with shorter migration distance lower spawning tended to have higher CTmax 90 days posthatch. However, the relationship was reversed when fish of similar size...

Force–frequency relationships and the dependence upon extracellular calcium as a source of activator were investigated using atrial strips from skipjack tuna (Katsuwonus pelamis). At 25 °C, active force generation increased over stimulation range 0.2–1.6 Hz declined at higher frequencies. Ryanodine, blocker release sarcoplasmic reticulum, decreased by ~30% but did not alter shape force–frequency curve. Uniform contractions maintained up to rates 3.0 following ryanodine application, compared...

A preparation was developed to perfuse the coronary circulation in working hearts from rainbow trout (Salmo gairdneri Richardson). The used examine pressure-flow relationships for as heart generated physiological and subphysiological work loads. Coronary vascular resistance increased exponentially flow rate decreased. also influenced by cardiac metabolism acclimation temperature. When increased, extravascular compression resistance. Direct vasoconstriction of vessels, produced injections...

We used an isometric muscle preparation to test the hypothesis that yellowfin tuna Thunnus albacares utilize intracellular Ca2+ storage sites of sarcoplasmic reticulum (SR) during routine contractions. Ryanodine (a blocker SR release) reduced force contraction by approximately 50 % and rates relaxation 60 in atrium. High levels adrenaline were unable ameliorate effects ryanodine. conclude is active contributing development at physiological frequencies. Further, we suggest that, using...

Oxygen consumption and maximum pumping performance were measured in situ perfused trout (Salmo gairdneri) hearts at acclimation temperatures of 5° 15° C. Myocardial oxygen increased linearly as a function myocardial power output both temperatures. The slope the regression equation was significantly lower C compared with that This difference attributed to related changes mechanical efficiency (but not C) mass-specfic for maximal larger heart cold-acclimated fish.

The cardiovascular effects of endothelin-1 (ET-1) in trout were examined unanesthetized fish, perfused tissues, and isolated vascular rings. In vivo, a bolus 500 ng/kg body wt ET-1 transiently lowered arterial (postgill) blood pressure (BP) by nearly 30%; 1,500 produced triphasic, pressor-depressor-pressor, response. Continuous infusion 0.1, 1, 10, 30 ng.kg-1.min-1 progressively BP but did not affect heart rate (HR), urine flow, or electrolyte excretion. the situ (10(-11) to 10(-8) M) had no...

The live release of wild adult Pacific salmon (Oncorhynchus spp.) following capture is a management tactic often used in commercial, aboriginal, and recreational fisheries. Fisheries handling can be both exhausting stressful to fish, which limit their ability swim survive after release. As result, researchers have assessed methods intended improve post-release survival by assisting the flow water over gills fish prior Such approaches use recovery bags or boxes that direct restrained fish....

The main finding of this study was that measuring maximum heart rate during incremental warming an effective tool to estimate upper thermal limits in three small cyprinid Danio species, which differed significantly. Arrhenius breakpoint temperature for rate, purportedly index optimum temperature, 21·2 ± 0·4, 20·1 0·4 and 18·9 0·8° C (mean s.e .) zebrafish rerio , pearl danio albolineatus glowlight choprae respectively. where cardiac arrhythmias were first induced ( T arr ) 36·6 0·7, 36·9 0·8...

ABSTRACT Haematological variables were measured during aerobic swimming (45–55% of Ucrit) and at critical velocity (Ucrit) in acutely splenectomized sham-operated rainbow trout. There was no correlation between haematocrit (Hct) Ucrit either group fish. The control values for the haematological did not differ significantly two groups Some changed Ucrit, but there significant differences any variables. Arterial blood oxygen tension reduced Ucrit. content maintained fish because Hct increased...

We present the first data on differences in routine and active metabolic rates for sexually maturing migratory adult sockeye salmon (Oncorhynchus nerka) that were intercepted ocean then held either seawater or freshwater. Routine oxygen uptake (MO2) significantly higher (27%-72%) than freshwater at all swimming speeds except those approaching critical speed. During a 45-min recovery period, declining postexercise remained 58%-73% When fish performed second swim test, again 28%-81% Despite...

ABSTRACT This study is the first to examine contractility of teleost ventricular muscle in an oscillating preparation. The experiments were designed test relative importance Ca2+ released from sarcoplasmic reticulum (SR) and influx across sarcolemma (SL) cardiac performance rainbow trout Oncorhynchus mykiss. Adrenaline ryanodine used modulate flux through SL SR, respectively. Experiments conducted at two temperatures (12 °C 22 °C) (1) investigate effect acute temperature change (from 12 on...

A method for quickly assessing the relative proportion of compact myocardium in ventricle teleosts is introduced and used juvenile Pacific tarpon Megalops cyprinoides , a member only air‐breathing elopomorph teleost genus. The increased with body mass, reaching up to 60% ventricular mass. finding was surprising discovery since recent literature has suggested that air breathing evolved primarily as means supplying oxygen fish heart during activity. present data, which represent first...

Relatively little is known about the physiological response and mortality consequences of return anadromous fish to freshwater (FW). We explored FW by collecting maturing sockeye salmon from marine waters off mouth Fraser River holding ∼50 in each five treatments: saltwater (SW; salinity = 28 ppt), iso‐osmotic water (ISO; 13 (0 SW + gonadotropin‐releasing hormone (SW GnRH), GnRH. Exogenous GnRH treatments were intended accelerate maturation. Results demonstrate that gill Na+,K+ ATPase...

Tunas are capable of exceptionally high maximum metabolic rates; such capability requires rapid delivery oxygen and substrate to the tissues. This requirement is met, in part, by cardiac outputs, opening possibility that myocardial Ca(2+) enhanced myocytes from tuna compared with those other fish. In this study, we investigated electrophysiological properties L-type channel current (I(Ca)) test hypothesis influx would be large have faster kinetics cardiomyocytes Pacific bluefin (Thunnus...