Respiratory and cardiac function during exercise in squid

1990 ◽  
Vol 68 (4) ◽  
pp. 792-798 ◽  
Author(s):  
Robert E. Shadwick ◽  
Ronald K. O'Dor ◽  
John M. Gosline
Keyword(s):  
Heart Rate ◽  
Stroke Volume ◽  
Swimming Speed ◽  
Oxygen Demand ◽  
Ventilation Rate ◽  
Critical Swimming Speed ◽  
Mechanical Coupling ◽  
Loligo Opalescens ◽  
Systemic Heart ◽  
Ventilatory Volume

We investigated the cardiorespiratory performance of the squid Loligo opalescens at rest and during jet locomotion while tethered in an aquarium or while swimming in a Brett respirometer at speeds ranging from 0.05 to 0.6 m∙s−1. Simultaneous records of systemic heart rate and ventilatory frequency at each swimming speed were used with data for oxygen consumption to calculate the cardiac output and stroke volume. For a squid of mean weight 0.03 kg and length 0.18 m the resting heart rate averaged 60/min, the ventilatory rate was 26/min, and the calculated stroke volume was 0.05 mL (0.9 mL∙g heart−1) at 12 °C. During exercise the increased oxygen demand was accommodated by increases in both heart rate and stroke volume of almost 100% at the critical swimming speed of about 0.34 m∙s−1. Concomitant increases in the ventilation rate (350%) and ventilatory volume (500%) due to the requirements of jet locomotion were much greater than needed to deliver oxygen to the gills. At rest the oxygen extraction from the respiratory stream was 11%, and this declined to 5% at the critical swimming speed. The possibility that mechanical coupling of the circulatory and respiratory pumps may occur during jet swimming is examined.

Haemolymph flow distribution, cardiac performance and ventilation during moderate walking activity in Cancer magister (Dana) (Decapoda, Crustacea)

1996 ◽  
Vol 199 (3) ◽  
pp. 627-633 ◽  
Author(s):  
B Wachter ◽  
B Mcmahon
Keyword(s):  
Heart Rate ◽  
Cardiac Output ◽  
Stroke Volume ◽  
Relative Proportion ◽  
Flow Distribution ◽  
Ventilation Rate ◽  
Arterial System ◽  
Cancer Magister ◽  
Walking Activity ◽  
Flow Through

Adult male Cancer magister (Dana) were equipped with pulsed-Doppler flowmeters and pressure transducers for simultaneous measurement of heart and ventilation frequencies, haemolymph flow through each of the major arterial systems and cardiac output and for calculation of stroke volume. Each variable was measured at rest and during two consecutive periods of moderate treadmill walking activity and recovery. During activity, haemolymph flow through the sternal and anterolateral arteries increased, while flow through the hepatic arterial system decreased. This resulted in a redistribution of haemolymph flow in which a proportion of cardiac output was shifted from the anterior, posterior and hepatic arterial systems to the sternal arterial system. The relative proportion of the cardiac output flowing through the anterolateral artery remained constant. This indicated that oxygen supply was shifted away from the digestive system to the muscles of the walking legs and the respiratory system. Cardiac output, heart rate and stroke volume all increased in response to activity. The increase in cardiac output is the result of a large increase in stroke volume and a small increase in heart rate. A doubling of ventilation rate also occurred during activity. Both the circulatory and ventilatory systems were restored to pre-activity values by 60 min of recovery.

Control of the systemic heart and the portal heart of Myxine glutinosa

1996 ◽  
Vol 199 (6) ◽  
pp. 1429-1434 ◽  
Author(s):  
M Johnsson ◽  
M Axelsson
Keyword(s):  
Heart Rate ◽  
Stroke Volume ◽  
Myxine Glutinosa ◽  
Beta Adrenoceptor ◽  
Output Pressure ◽  
In Situ Perfusion ◽  
Adrenoceptor Antagonist ◽  
Heart Preparation ◽  
Spontaneous Contractions ◽  
Systemic Heart

The effects of preload and afterload on the performance of the systemic heart of the hagfish Myxine glutinosa were investigated before and during sotalol treatment using an in situ perfusion technique. Elevation of input pressure (preload) increased flow by means of increased stroke volume and heart rate in accordance with Starling's law of the heart, while increased output pressure (afterload) decreased flow mainly because of decreased stroke volume. Treatment with the beta-adrenoceptor antagonist sotalol did not change the quality of the responses to increased preload or afterload, although power output decreased by 40 % and flow rate was reduced by 35 % mainly due to a decrease in heart rate. Isolated preparations of the systemic heart and the portal heart provided information on the chronotropic effects of different agonists and antagonists. Both the systemic heart and the portal heart were insensitive to adrenergic and cholinergic agonists, adrenocorticotropic hormone and the cholinoceptor antagonist atropine. Sotalol treatment lowered the rate of spontaneous contractions by 30 % in the systemic heart preparation and by 21 % in the portal heart preparation. This study has given further evidence for the existence of a tonic beta-adrenoceptor stimulation of the hagfish systemic heart and portal heart, and demonstrated the importance of that stimulation in maintaining systemic heart performance.

HEART COMPLICATIONS IN HYPERTHYROIDISM

2011 ◽  
pp. 7-17
Author(s):  
Hai Thuy Nguyen ◽  
Anh Vu Nguyen
Keyword(s):  
Atrial Fibrillation ◽  
Blood Pressure ◽  
Heart Rate ◽  
Heart Diseases ◽  
Systolic Dysfunction ◽  
Oxygen Demand ◽  
Left Ventricular ◽  
Cardiac Contraction ◽  
Cardiac Complications ◽  
Cardiac Symptoms

Thyroid hormone increases the force of the contraction and the amount of the heart muscle oxygen demand. It also increases the heart rate. Due to these reasons, the work of the heart is greatly increased in hyperthyroidism. Hyperthyroidism increases the amount of nitric oxide in the intima, lead them to be dilated and become less stiff. Cardiac symptoms can be seen in anybody with hyperthyroidism, but can be particularly dangerous in whom have underlying heart diseases. Common symptoms include: tachycardia and palpitations. Occult hyperthyroidism is a common cause of an increased heart rate at rest and with mild exertion. Hyperthyroidism can also produce a host of other arrhythmias such as PVCs, ventricular tachycardia and especially atrial fibrillation. Left ventricular diastolic dysfunction and systolic dysfunction, Mitral regurgitation and mitral valve prolapsed are heart complications of hyperthyroism could be detected by echocardiography. The forceful cardiac contraction increases the systolic blood pressure despite the increased relaxation in the blood vessels reduces the diastolic blood pressure. Atrial fibrillation, atrial enlargement and congestive heart failure are important cardiac complications of hyperthyroidism. An increased risks of stroke is common in patients with atrial fibrillation. Graves disease is linked to autoimmune complications, such as cardiac valve involvement, pulmonary arterial hypertension and specific cardiomyopathy. Worsening angina: Patients with coronary artery disease often experience a marked worsening in symptoms with hyperthyroidism. These can include an increase in chest pain (angina) or even a heart attack.

scholarly journals Evaluation of Stroke Volume Variation Obtained by the FloTrac™/Vigileo™ System to Guide Preoperative Fluid Therapy in Patients Undergoing Brain Surgery

2012 ◽  
Vol 40 (3) ◽  
pp. 1175-1181 ◽  
Author(s):  
J Li ◽  
Fh Ji ◽  
Jp Yang
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Stroke Volume ◽  
Stroke Volume Variation ◽  
Brain Surgery ◽  
Fluid Loading ◽  
Volume Loading ◽  
Fluid Infusion ◽  
Volume Variation ◽  
Ringer’S Lactate

OBJECTIVE: The accuracy of stroke volume variation (SVV) obtained by the FloTrac™/Vigileo™ system in otherwise healthy patients undergoing brain surgery was assessed. METHODS: Anaesthesia was induced in 48 patients with minimal fluid infusion. Before surgery, fluid volume loading was performed by infusion with Ringer's lactate solution in 200 ml steps over 3 min, repeated successively if the patient responded with an increase in stroke volume of ≥ 10%, until the increase was < 10% (nonresponsive). RESULTS: A total of 157 volume loading steps were performed in the 48 patients. Responsive and nonresponsive steps differed significantly in baseline values of blood pressure, heart rate and SVV. Significant correlations were found between the change in stroke volume after fluid loading and values of blood pressure, heart rate and SVV before fluid loading, with SVV the most sensitive variable. CONCLUSION: Stroke volume variation obtained using the FloTrac™/Vigileo™ system is a sensitive predictor of fluid responsiveness in healthy patients before brain surgery.

Respiratory development in Arctic char Salvelinus alpinus under conditions of normoxia and chronic hypoxia

1977 ◽  
Vol 55 (9) ◽  
pp. 1461-1467 ◽  
Author(s):  
D. G. McDonald ◽  
B. R. McMahon
Keyword(s):  
Heart Rate ◽  
Surface Morphology ◽  
Chronic Hypoxia ◽  
Prolonged Exposure ◽  
Salvelinus Alpinus ◽  
Ventilation Rate ◽  
Arctic Char ◽  
Adult Fish ◽  
Weighted Averages ◽  
Secondary Lamellae

Changes in surface morphology of the gills, ventilation rate, and heart rate were examined in Arctic char larvae exposed to normoxia (pO2 = 121 ± 6 (SE) mmHg) or chronic hypoxia (pO2 = 33 ± 3.5 mmHg) for 47 days after hatching. A modified weighted-averages technique was developed to measure aspects of gill morphology.Early development of the gills was characterized by rapid increases in filament size and number, and the emergence and proliferation of secondary lamellae. Variations in the dimensions of the gills, as noted in adult fish, were particularly evident in the larval fish.Hypoxia caused increases in both ventilation rate and heart rate. Prolonged exposure led to a retardation of gill growth, particularly the proliferation of secondary lamellae. However, growth of individual lamellae was stimulated between 38 and 47 days.

Haemodynamic Effects of Different Beta Blockers in Angina Pectoris

1977 ◽  
Vol 22 (1) ◽  
pp. 64-68 ◽  
Author(s):  
H. Åström ◽  
B. Jonsson
Keyword(s):  
Heart Rate ◽  
Angina Pectoris ◽  
Stroke Volume ◽  
Partial Agonist ◽  
Beta Blockers ◽  
Haemodynamic Effects ◽  
Agonist Activity ◽  
Peripheral Vascular ◽  
Reduce Heart Rate ◽  
Beta Blocking

Beta-blocking agents with partial agonist activity seem to reduce heart rate at rest slightly less than those without this property. Cardio-selective drugs have no effect on stroke volume at rest contrary to the non-selective ones which will reduce it somewhat. This difference is abolished during exercise. The only difference seen during work between different beta-blockers is the effect on the peripheral vascular resistance. The selective drugs lower the arterial pressure with unchanged resistance.

The effect of diabetes on heart rate and other determinants of myocardial oxygen demand in acute coronary syndromes

2004 ◽  
Vol 21 (9) ◽  
pp. 1025-1031 ◽  
Author(s):  
K. Foo ◽  
N. Sekhri ◽  
C. Knight ◽  
A. Deaner ◽  
J. Cooper ◽  
...  
Keyword(s):  
Heart Rate ◽  
Acute Coronary Syndromes ◽  
Oxygen Demand ◽  
Myocardial Oxygen Demand ◽  
Coronary Syndromes

Matching the Heart to Heat-Induced Circulatory Load: Heat-Acclimatory Responses

Physiology ◽  
2003 ◽  
Vol 18 (6) ◽  
pp. 215-221 ◽  
Author(s):  
Michal Horowitz
Keyword(s):  
Heart Rate ◽  
Oxygen Demand ◽  
Heat Acclimation ◽  
Regulatory Proteins ◽  
Contractile Apparatus ◽  
Cardiac Efficiency ◽  
Cross Tolerance ◽  
Altered Expression ◽  
Expression Of Genes ◽  
Cardiac Adaptation

Heat acclimation enhances cardiac efficiency by increasing stroke volume and decreasing heart rate. These adaptations involve biochemical changes in the contractile apparatus, switched on by altered expression of genes coding contractile and calcium-regulatory proteins and partially mediated by persistent low thyroxine. Heat acclimation also produces cross-tolerance to oxygen deprivation, thus reinforcing cardiac adaptation to oxygen demand/supply mismatching via energy-sparing pathways.

First clinical trial with etomoxir in patients with chronic congestive heart failure

2000 ◽  
Vol 99 (1) ◽  
pp. 27-35 ◽  
Author(s):  
Stephan SCHMIDT-SCHWEDA ◽  
Christian HOLUBARSCH
Keyword(s):  
Heart Failure ◽  
Heart Rate ◽  
Sarcoplasmic Reticulum ◽  
Left Ventricular Ejection Fraction ◽  
Ejection Fraction ◽  
Stroke Volume ◽  
Left Ventricular ◽  
Ventricular Ejection ◽  
Left Ventricular Ejection ◽  
Ventricular Ejection Fraction

In the failing human myocardium, both impaired calcium homoeostasis and alterations in the levels of contractile proteins have been observed, which may be responsible for reduced contractility as well as diastolic dysfunction. In addition, levels of a key protein in calcium cycling, i.e. the sarcoplasmic reticulum Ca2+-ATPase, and of the α-myosin heavy chain have been shown to be enhanced by treatment with etomoxir, a carnitine palmitoyltransferase inhibitor, in normal and pressure-overloaded rat myocardium. We therefore studied, for the first time, the influence of long-term oral application of etomoxir on cardiac function in patients with chronic heart failure. A dose of 80 mg of etomoxir was given once daily to 10 patients suffering from heart failure (NYHA functional class II–III; mean age 55±4 years; one patient with ischaemic heart disease and nine patients with dilated idiopathic cardiomyopathy; all male), in addition to standard therapy. The left ventricular ejection fraction was measured echocardiographically before and after a 3-month period of treatment. Central haemodynamics at rest and exercise (supine position bicycle) were defined by means of a pulmonary artery catheter and thermodilution. All 10 patients improved clinically; no patient had to stop taking the study medication because of side effects; and no patient died during the 3-month period. Maximum cardiac output during exercise increased from 9.72±1.25 l/min before to 13.44±1.50 l/min after treatment (P < 0.01); this increase was mainly due to an increased stroke volume [84±7 ml before and 109±9 ml after treatment (P < 0.01)]. Resting heart rate was slightly reduced (not statistically significant). During exercise, for any given heart rate, stroke volume was significantly enhanced (P < 0.05). The left ventricular ejection fraction increased significantly from 21.5±2.6% to 27.0±2.3% (P < 0.01). In acute studies, etomoxir showed neither a positive inotropic effect nor vasodilatory properties. Thus, although the results of this small pilot study are not placebo-controlled, all patients seem to have benefitted from etomoxir treatment. Etomoxir, which has no acute inotropic or vasodilatory properties and is thought to increase gene expression of the sarcoplasmic reticulum Ca2+-ATPase and the α-myosin heavy chain, improved clinical status, central haemodynamics at rest and during exercise, and left ventricular ejection fraction.

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