...A. Kurt Gamperl; Alexander L. Thomas; Douglas A. Syme ABSTRACT Fish increase heart rate ( f H ), not stroke volume ( V S ), when acutely warmed as a way to increase cardiac output ( Q ). To assess whether aspects of myocardial function may have some basis in determining temperature-dependent...

... nitroprusside SV stressed blood volume USV unstressed blood volume VR venous return V S stroke volume Q̇ sys is the product of f H and systemic stroke volume ( V S ), and may, therefore, change as one or both of these variables changes (i.e. frequency- or volume...

... flow magnetic resonance imaging (MRI) – to validate stroke volume measurements and end diastolic ventricular blood volume. This produced an estimate of ejection fraction in our study species, the red footed tortoise Chelonoidis carbonarius ( n =5), under isoflurane anaesthesia of 88±11%. After...

...-eared slider turtle ( Trachemys scripta elegans ), we demonstrated that activation of smooth muscle contraction with histamine (100 nmol kg −1 bolus injected into perfusate) reduced cardiac output by decreasing stroke volume (>50% decrease in both parameters). Conversely, inhibition of smooth muscle...

... to the internal organs, and the stroke volume and cardiac output during the surface state. We then simulated breath-holding conditions and perfusion of the internal organs under the diving-induced bradycardia and reduction of stroke volume and cardiac output, using 10 beats min −1 as the limit for the heart rate...

... breakpoint temperature as the red-blooded Antarctic fish Notothenia coriiceps . Cardiac output Heart rate Stroke volume ECG Warming Sympathovagal balance The notothenioid suborder of fishes that are dominant in the frigid Southern Ocean include the remarkable haemoglobinless (Hb...

... and the extinct pterodactyls. Given that powered flight represents a demanding aerobic activity, an efficient cardiovascular system is essential for the continuous delivery of oxygen to the pectoral muscles during flight. It is well known that the limiting step in the circulation is stroke volume (the volume...

...William Joyce; Michael Axelsson; Tobias Wang ABSTRACT Most vertebrates increase cardiac output during activity by elevating heart rate with relatively stable stroke volume. However, several studies have demonstrated ‘intrinsic autoregulation’ of cardiac output where artificially increased heart...

..., the blood-oxygen carrying capacity was higher than that of barnacle geese. Resting cardiac output also did not differ between groups and increased at least twofold during progressive hypoxia, initially as a result of increases in stroke volume. However, cardiac output increased at a higher F i O 2 threshold...

... pressures to calculate left ventricular wall stress. Cardiac output was also determined by inert gas rebreathing to provide an additional and independent estimate of stroke volume. Echocardiography and inert gas-rebreathing yielded similar cardiac outputs of 16.1±2.5 and 16.4±1.4 l min −1 , respectively...

... and adjacent vessels were measured by magnetic resonance imaging. In synthetic seawater at 23°C (immersed condition), the end-diastolic volume (EDV), end-systolic volume (ESV) and stroke volume (SV) were 50%, 21% and 29% of the heart volume, respectively, and the auricle volume ( V A ) was maximized at end...

... differences in basic lymph heart functions. The end diastolic volumes of posterior lymph hearts averaged 10.8 μl kg –1 in R. marina and 7.9–10.8 μl kg –1 in L. catesbeianus by conductance manometry, and 9–32 μl kg –1 in R. marina by ultasound techniques, which correlated with body mass. Stroke volumes were...

... (CgA 344-364 ) on the eel heart, as well as the eventual species-specific mechanisms of its myocardial action. Experiments were carried out on fresh-water eels ( Anguilla anguilla L.) using an electrically paced isolated working heart preparation. Stroke volume and stroke work were used as measures...

... cardiovascular barnacle goose rate of oxygen consumption stroke volume 2009 25 6 2009 * Author for correspondence( [email protected] ) For each sampling period in the captive barnacle geese, with both whole-animal and mass-specific values of V̇ O 2 , there was a significant...

... pressure of oxygen in venous blood, P v O 2 ) and,secondarily, because the fish heart has an unusual ability to produce large increases in cardiac stroke volume ( V SH ) that allow cardiac output to be maintained during hypoxic bradycardia. Among the putative benefits of hypoxic bradycardia is an increase...

... to air-breathe. An elevation of heart rate decreases cardiac filling time and therefore may cause a decline in stroke volume ( V S ), but this can be compensated for by an increase in venous tone to maintain stroke volume. Thus, the study on S. marmoratus was undertaken to investigate how stroke volume...

..., Canada (e-mail: [email protected] ) 9 5 2006 © The Company of Biologists Limited 2006 2006 Gadus morhua temperature cardiac output heart rate stroke volume metabolic rate haemoglobin blood oxygen concentration Temperature is an important environmental factor...

... Imaging and phase contrast flow analysis to obtain accurate flow measurements from the base of the aorta. Heart rate ( f h )and cardiac output ( Q̇ ) were measured before, during and after dives in four restrained juvenile northern elephant seals, Mirounga angustirostris , and stroke volume( V s...

... of similarities and important differences. Although the avian allometric equations from this earlier study accurately predicted the flight Q̇ of our pigeons, this was primarily due to due to compensating discrepancies in their heart rate and stroke volume predictions. Additionally, the measured heart mass( M H...

..., respectively), but not P da . In spite of an increased preload, the increase in Q̇ was exclusively mediated by an increased heart rate ( f h , from 80±4 beats min -1 to 88±4 and 103±3 beats min -1 ,respectively), and stroke volume ( V s ) remained unchanged. Prazosin treatment (1 mg kg -1 M b ) abolished...