scholarly journals The Rate of Oxygen Uptake of Quiescent Cardiac Muscle

1960 ◽  
Vol 44 (2) ◽  
pp. 235-249 ◽  
Author(s):  
Paul F. Cranefield ◽  
Kalman Greenspan
Keyword(s):  
Oxygen Uptake ◽  
Cardiac Muscle ◽  
Papillary Muscle ◽  
Oxygen Electrode ◽  
Papillary Muscles ◽  
Cent Oxygen ◽  
Wet Weight ◽  
Cat Heart

The rate of oxygen uptake of quiescent papillary muscle of the cat heart has been determined in a flow respirometer with the use of the oxygen electrode. The apparent rate of oxygen uptake as a function of the diameter of the muscle was also determined. It was found that papillary muscles from cat hearts use oxygen at a rate of 2.84 (microliters/mg. wet weight)/hour at a temperature of 35°C. Such muscles can be adequately supplied by diffusion when their surface is uniformly exposed to an atmosphere containing 95 per cent oxygen only if their diameter is 0.64 mm. or less. Papillary muscles from kitten hearts use oxygen at a rate of 4.05 (microliters/mg. wet weight)/hour at a temperature of 35°C. Such muscles can be adequately supplied by diffusion when their surface is uniformly exposed to an atmosphere containing 95 per cent oxygen only if their diameter is 0.53 mm. or less. If the muscles are small enough to be adequately supplied with oxygen by diffusion, the rate of oxygen uptake does not increase when the muscle is stretched.

Effect of hypoxia on mechanical properties of hyperthyroid cat papillary muscle

1979 ◽  
Vol 237 (3) ◽  
pp. H293-H298
Author(s):  
I. Palacios ◽  
K. Sagar ◽  
W. J. Powell
Keyword(s):  
Mechanical Properties ◽  
Right Ventricular ◽  
Cardiac Muscle ◽  
Papillary Muscle ◽  
Similar Degree ◽  
Hypoxic Stress ◽  
Papillary Muscles ◽  
Tension Development ◽  
Cat Papillary Muscle ◽  
Myocardial Relaxation

It has been previously established that hyperthyroid myocardium exhibits increased performance under well-oxygenated conditions. To date, it is not known whether hyperthyroid cardiac muscle can maintain this increased performance during hypoxia. The responses of isolated right ventricular papillary muscles from hyperthyroid and euthyroid kittens to hypoxia were compared under isometric conditions at 31 degrees C. Under well-oxygenated conditions, the hyperthyroid cardiac muscle exhibited both an increased contractility and an accelerated rate of relaxation. A similar degree of acute hypoxic stress for 15 min resulted in a greater decrease in contractility in the hyperthyroid compared with the euthyroid papillary muscle as indicated by a greater fall in both peak tension development (2.2 +/- 0.25 from 4.2 +/- 0.2 vs. 0.9 +/- 0.15 from 3.2 +/- 0.4 g/mm2, P less than 0.01) and +dT/dt (12.9 +/- 2.3 from 25 +/- 3 vs. 4.0 +/- 0.6 from 14 +/- 1 g-s-1-mm-2, P less than 0.01). In addition, compared with the euthyroid data, hypoxia resulted in impaired myocardial relaxation in the hyperthyroid cardiac muscle. Thus, the hyperthyroid compared with the euthyroid papillary muscle exhibits both a greater decrease in contractility and an impairment of myocardial relaxation during hypoxia, indicating a greater susceptibility to a given hypoxic stress.

scholarly journals Cat Heart Muscle in Vitro

1960 ◽  
Vol 44 (2) ◽  
pp. 327-344 ◽  
Author(s):  
Ernest Page ◽  
A. K. Solomon
Keyword(s):  
Papillary Muscles ◽  
Total Water ◽  
Inulin Space ◽  
Wet Weight ◽  
K Concentration ◽  
Cell Volumes ◽  
Cat Heart ◽  
External K

Methods have been developed for the simultaneous determination of total water, inulin space, and K and Na content in muscles of 0.5 to 10 mg. wet weight. These methods have been used to define steady state conditions with respect to intracellular K concentration in papillary muscles from cat hearts perfused and contracting isometrically at 27–28°C. and at 37–38°C. Cell volumes and intracellular ionic concentrations have been followed as a function of the external K concentration and compared with values predicted on the basis of electroneutrality and osmotic equilibrium.

scholarly journals A STUDY OF INOTROPIC MECHANISMS IN THE PAPILLARY MUSCLE PREPARATION

1959 ◽  
Vol 42 (3) ◽  
pp. 533-561 ◽  
Author(s):  
B. C. Abbott ◽  
W. F. H. M. Mommaerts
Keyword(s):  
Cardiac Muscle ◽  
Papillary Muscle ◽  
Active State ◽  
Muscle Preparation ◽  
Series Elasticity ◽  
Velocity Relation ◽  
Force Velocity ◽  
Cat Heart

The length-tension diagram, the force-velocity relation, the characteristics of the series elasticity, and the duration of the active state have been studied on the papillary muscle preparation of the cat heart, and on other examples of cardiac muscle. Positive inotropic changes such as the staircase phenomenon and post-extrasystolic potentiation occur without lengthening, but frequently with shortening, of the duration of the active state. They are accompanied by an increased velocity of contraction, and may be caused either by an intensification of the active state or by an alteration of the force-velocity characteristics of the contractile component. The changes in the force-velocity relation point to an adaptation of the velocity-efficiency relation in dependence on the frequency of contraction.

Inter-Basal and Septal Connections of Papillary Muscles - An Anatomical Rationale for Rhythmic Opening of AV Valves - A Multicentric Medical College Based Cross Sectional Study

2021 ◽  
Vol 8 (31) ◽  
pp. 2865-2869
Author(s):  
Praveen Mulki Shenoy ◽  
Amith Ramos ◽  
Narasimha Pai ◽  
Bharath Shetty ◽  
Aravind Pallipady Rao
Keyword(s):  
Left Ventricle ◽  
Papillary Muscle ◽  
Interventricular Septum ◽  
Cross Sectional Study ◽  
Papillary Muscles ◽  
Cross Sectional ◽  
Medical College ◽  
Moderator Band ◽  
Almost All ◽  
And Function

BACKGROUND The papillary muscle basal connections have significant clinical implications. Variety of studies done on its morphology and function by various specialists in different departments. A close look on these revealed the interconnections of papillary muscles to one another and to the interventricular septum of both ventricles is related to uncoordinated contractions of papillary muscles, leading to hyper or hypokinesia or prolapse or even its rupture. METHODS Our study done in 25 formalin soaked hearts revealed after the deep and meticulous dissection, reflecting the walls of ventricles laterally the numerous interconnections of papillary muscles at its bases and IVS. Ventricles are opened by inverted ‘L’ shaped incision and its reflected more laterally till all the papillary muscles is visible in one frame after incising the moderator band. The connections were noted, measured, photographed, tabulated, compared with similar studies and analysed with experts with respective fields. RESULTS Almost all the specimens did have the interconnections. Further the post mortem findings of the cardiac related deaths with involvement of papillary muscles suggest damage to such ‘bridges’. The moderator band extensions to the base of right APM, and its extension to the posterior groups is noted in all the specimens. The bridge from the IVS to bases of both the groups of papillary muscles is noted in left ventricle. In90% of specimens the one PPM is found to be loosely connected, more so in left ventricle. CONCLUSIONS We are of a conclusion that such basal interconnections and to the interventricular septum are responsible for rhythmic contractions of papillary muscles of both ventricles. Since the AV valves have to open simultaneously, interconnections becomes mandatory as the impulse has to reach it before it reaches the trabeculae carniae. One of the Posterior papillary muscles is loosely connected to other papillary muscles, may be the reason for its rupture, more so in left ventricle. KEYWORDS Papillary Muscle, Interbasal Connection, Moderator Band, Valvular Prolapse, AV Valves

THE EFFECT OF ACETYLCHOLINE ON ADRENALINE-INDUCED SUBATRIAL RHYTHMS IN THE SENSITIZED CAT HEART

1964 ◽  
Vol 42 (4) ◽  
pp. 431-445 ◽  
Author(s):  
Don P. MacLeod ◽  
A. K. Reynolds
Keyword(s):  
Petroleum Ether ◽  
Papillary Muscle ◽  
Antiarrhythmic Agent ◽  
Ventricular Automaticity ◽  
Cat Heart

Acetylcholine has been shown to be an effective antiarrhythmic agent against arrhythmias induced by adrenaline in combination with the myocardial sensitizers petroleum ether, halothane, and harman methosulphate. It has also been shown that acetylcholine will reduce or prevent the increase in ventricular automaticity produced by adrenaline in the intact cat and in the isolated papillary muscle of the cat. All of these actions of acetylcholine can be blocked by atropine. Evidence from experiments in which petroleum ether inhalation was begun after an arrhythmia had been induced by adrenaline indicated that petroleum ether was causing an increase in ventricular automaticity. The results appear to support the idea that petroleum ether and possibly other sensitizers interfere with the stabilizing action of endogenous acetylcholine on the ventricle and allow the stimulating action of adrenaline to produce severe prefibrillatory rhythms by an increase in ventricular automaticity.

Calcium is released from the junctional sarcoplasmic reticulum during cardiac muscle contraction

1991 ◽  
Vol 260 (3) ◽  
pp. H989-H997 ◽  
Author(s):  
C. S. Moravec ◽  
M. Bond
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Muscle Contraction ◽  
Cardiac Muscle ◽  
Electron Probe Microanalysis ◽  
Electron Probe ◽  
Storage Site ◽  
Papillary Muscles ◽  
Cardiac Muscle Contraction ◽  
Intracellular Storage ◽  
Junctional Sarcoplasmic Reticulum

We have used electron-probe microanalysis (EPMA) to address the question of Ca2+ release by junctional sarcoplasmic reticulum (JSR) as well as Ca2+ regulation by mitochondria (MT) during cardiac muscle contraction. Hamster papillary muscles were rapidly frozen during relaxation or at the peak rate of tension rise (+dT/dt). Total Ca2+ content was measured by EPMA in the JSR, within a MT, over the A band, and in the whole cell, in nine cells per animal (five animals per group). JSR Ca2+ content was found to be significantly lower in muscles frozen at the peak of contraction [7.3 +/- 1.3 (mean +/- SE) mmol Ca2+/kg dry wt] than in those frozen during relaxation (12.5 +/- 1.9 mmol Ca2+/kg dry wt; P less than 0.01), suggesting that Ca2+ is released from this storage site during cardiac muscle contraction. In contrast, MT Ca2+ content did not change significantly during contraction (0.4 +/- 0.1 mmol/kg dry wt) compared with relaxation (0.1 +/- 0.2 mmol/kg dry wt). A third group of muscles was frozen during relaxation after pretreatment with 10(-7) M ryanodine. Ca2+ content of the JSR was significantly decreased (P less than 0.01) in this group of muscles, (6.4 +/- 1.8 mmol/kg dry wt) compared with those frozen during relaxation in the absence of the drug. This suggests that the intracellular storage site with a decreased Ca2+ content in muscles frozen at the peak of contraction is the ryanodine-releasable store. These results provide the first direct measurement of the Ca2+ content of both JSR and MT during a normal cardiac muscle contraction and demonstrate that Ca2+ is released from the JSR during muscle contraction.

Influence of Glucose on Contractile Activity of Papillary Muscle During and After Anoxia

1956 ◽  
Vol 187 (1) ◽  
pp. 135-138 ◽  
Author(s):  
Martin M. Winbury
Keyword(s):  
Right Ventricle ◽  
Papillary Muscle ◽  
Contractile Activity ◽  
Oxygen Deficiency ◽  
Full Recovery ◽  
Papillary Muscles ◽  
Anaerobic Conditions ◽  
Aerobic Conditions ◽  
Deficient Medium ◽  
The Right

Papillary muscles from the right ventricle of the cat were subjected to periods of anoxia ranging from 15–60 minutes with and without glucose in the Krebs-Henseleit (bicarbonate) solution. Under aerobic conditions glucose was not required in the medium for the maintenance of contraction strength. Under anaerobic conditions the contraction strength decreased rapidly and after 30 minutes of oxygen deficiency contractile activity ceased. Reintroduction of oxygen after 15 minutes of anoxia resulted in full recovery of contraction strength for both control and glucose deficient muscles. After longer periods of anoxia, aerobic recovery was greater for muscles with glucose present during the anaerobic period. Little aerobic recovery was noted for muscles in glucose deficient medium during the 60 minutes of anoxia.

scholarly journals A comparative study of the morphology of mammalian true chordae tendineae of the atrioventricular valves

2015 ◽  
Vol 32 (02) ◽  
pp. 071-077 ◽  
Author(s):  
J. Hutchison ◽  
P. Rea
Keyword(s):  
Tricuspid Valve ◽  
Papillary Muscle ◽  
Papillary Muscles ◽  
Atrioventricular Valve ◽  
Chordae Tendineae ◽  
Atrioventricular Valves ◽  
Abrupt Transition ◽  
Significant Difference ◽  
Cardiac Valve Replacement ◽  
Transition Areas

Abstract Introduction: There is little literature on the subvalvular apparatus of the atrioventricular valves' of the heart. This investigation aimed to compare mammalian atrioventricular valve subvalvular apparatus; in particular the number and characteristics of true chordae tendineae (TChT) and their tissue transition areas - proximally with the valve leaflets, and distally with the papillary muscles. Materials and Methods: Sheep, pig and bovine fresh hearts were dissected (n = 9). The subvalvular apparatus of the mitral and tricuspid valves were visualised. Each TChT origin was grouped and counted according to papillary muscle and valve, and compared within and across the species. Appropriate statistical analyses were then applied to identify any correlations. Histological examination of the transition areas was also performed. Results: The tricuspid valve had significantly more TChT than the mitral (p = 0.04). On comparison of the TChT counts in both valves across the species, there were no signiicant differences. An unexpected inding was the abrupt transition from chordae collagen to papillary muscle. Conclusion: The tricuspid valve is under less pressure than the mitral but is connected to significantly more TChT. We have shown no significant difference between the numbers of TChT for each papillary muscle in either mitral or tricupsid valves across the species. Veterinary teaching emphasises that there is no clinically signiicant difference at a gross morphology level between these species. This is the irst study to report that there is also no signiicant difference at the subvalvular level, and this has direct translational relevance for bioprosthetic cardiac valve replacement.

Effect of epinephrine on stress relaxation and distensibility of the isolated cat heart

1965 ◽  
Vol 209 (5) ◽  
pp. 935-940 ◽  
Author(s):  
John K. Leach ◽  
Robert S. Alexander
Keyword(s):  
Stress Relaxation ◽  
Direct Effect ◽  
Papillary Muscles ◽  
Contraction Process ◽  
Diastolic Relaxation ◽  
Cat Heart

To investigate the cause of the rapid relaxation observed in the epinephrine-stimulated heart, stress relaxation and distensibility have been measured in the isolated perfused cat heart and in isolated papillary muscles. During epinephrine stimulation, distensibility was slightly increased but there was no change in the rate of stress relaxation. This would suggest that the action of epinephrine is confined to the contractile elements without any direct effect on the viscoelastic elements responsible for stress relaxation. The rapid diastolic relaxation observed in these hearts therefore relates to the dynamics of the contraction process rather than to lowered myocardial viscosity.

Isotonic relaxation in cardiac muscle

1975 ◽  
Vol 229 (3) ◽  
pp. 646-651 ◽  
Author(s):  
JE Strobeck ◽  
AS Bahler ◽  
EH Sonnenblick
Keyword(s):  
Cardiac Muscle ◽  
Isometric Force ◽  
Muscle Length ◽  
Constant Load ◽  
Papillary Muscles ◽  
Initial Length ◽  
Total Load ◽  
Relaxation Velocity ◽  
Force Velocity ◽  
Maximum Isometric Force

The force-velocity-length determinants of isotonic relaxation were studied in 12 cat papillary muscles. Isotonic relaxation velocity (VL) was found to be a function of total load (preload + afterload), with peak VL increasing to a maximum at loads approximately .3 to .4 Po(L') (Po(L') defined as maximum isometric force developed during a twitch at the experimental length) and falling with increasing loads. Initial muscle length (ML) had no effect on the peak VL with constant load. Increasing the initial length at which isotonic relaxation occurred (LL) decreased peak VL but did not alter the unique length-velocity trajectory at constant load. This unique length-velocity trajectory occurred, despite a wide variation in time during the contraction when peak VL was measured. Increasing Ca++ from 2.5 to 7.5 mM increased peak VL (1.73 +/- .16 to 2.32 +/- .20 ML/s) and shifted the entire length-velocity trajectory toward higher velocities of lengthening. The addition of 10 mM caffeine increased peak VL also (1.67 +/- .18 to 2.54 +/- .20 ML/s) and had a similar effect on the length-velocity trajectory during lengthening as Ca++. Both increased Ca++ and caffeine (10 mM) augmented the maximum VL measured on addition of load.

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