Effects of (?)-Phenylephrine on force of contraction in the presence of cocaine and hydrocortisone in cat papillary muscle

1984 ◽  
Vol 328 (1) ◽  
pp. 90-93 ◽  
Author(s):  
Andreas M�gge ◽  
Charlotte Reupcke ◽  
Wilhelm Schmitz ◽  
Hasso Scholz
Keyword(s):  
Papillary Muscle ◽  
Force Of Contraction ◽  
Cat Papillary Muscle

scholarly journals Length-dependent calcium inotropism in cat papillary muscle.

1977 ◽  
Vol 40 (4) ◽  
pp. 366-371 ◽  
Author(s):  
L L Huntsman ◽  
D K Stewart
Keyword(s):  
Papillary Muscle ◽  
Cat Papillary Muscle

Effects of stretch on mechanical and electrical properties of cardiac muscle

1963 ◽  
Vol 204 (3) ◽  
pp. 433-438 ◽  
Author(s):  
Zia J. Penefsky ◽  
Brian F. Hoffman
Keyword(s):  
Relaxation Time ◽  
Electrical Properties ◽  
Papillary Muscle ◽  
Ground Squirrel ◽  
Action Potentials ◽  
Ventricular Wall ◽  
Contraction Time ◽  
Cat Papillary Muscle ◽  
Mechanical And Electrical Properties ◽  
Transmembrane Action Potentials

A comparative study was made of effects of stretch on cat papillary muscle and auricle strips, hamster ventricular wall, ground squirrel ventricular strip, chicken auricle and ventricle, terrapin auricle and ventricle strips, and carp ventricle. In all species mild stretch increased contractile tension, excessive stretch decreased it, and velocity of conduction was constant with mild stretch but decreased with excessive stretch. In homeotherms under mild stretch, contraction time was unchanged and increased contractile tension was accompanied by increase in velocity of contraction. Under excessive stretch contraction time increased despite decreasing contractile tension. In poikilotherms contraction time and contractile tension were increased by mild stretch. Contraction time decreased with excessive stretch. Stretch increased relaxation time in all species. The evidence suggests that decrease in contractile tension with stretch is related, at least in the initial phases, to a change in excitability and conduction. In all species mild stretch was without effect on transmembrane action potentials, whereas at excessive stretch resting potentials and overshoot declined and rise time of the action potential was greatly increased. At excessive stretch surface-recorded potentials exhibited polyphasic deflections. All observed responses to stretch were reversible. Immediately after stretch the fibers were slightly elongated but developed a higher maximal contractile tension, and contraction time also was slightly increased.

Enhanced contractility during relaxation of cat papillary muscle

1975 ◽  
Vol 228 (6) ◽  
pp. 1708-1716 ◽  
Author(s):  
BG Bass
Keyword(s):  
Papillary Muscle ◽  
Time Course ◽  
Isometric Tension ◽  
Contractile Element ◽  
Cat Papillary Muscle ◽  
Postextrasystolic Potentiation ◽  
Peak Tension ◽  
Time To Peak ◽  
In Series ◽  
Antecedent Control

Contractility during relaxation of isometric tension was studied in isolated, electrically driven cat papillary muscle by interpolation of test extrasystoles, all of whichpartially fused with their antecedent (control) contractions, were separated by computer from the fused contractions and then analyzed. The time course of the restitutionof contractility during relaxation was defined by plotting maximal positive dT/dt andtime-to-peak tension of the computer-separated extrasystole versus delay preceding the extrasystole. The dT/dt and time-to-peak tension, which steadily decline with progressive prematurity between contractions, both increase again during late relaxation, become progressively greater still earlier in relaxation, peak shortly after peak isometric tension, and then again decline. This phase of an apparently enhanced contractilityduring relaxation is depressed in low Ca'++ and is transmitted into the postextrasystolic period (in which it is superimposed on the usual postextrasystolic potentiation). The possible contributions of variations in series-elastic component and contractile-element lengths, actionpotential characteristics, and other factors on contractility during relaxation are discussed. It is suggested that enhanced contractility during relaxation may also be related in part to the decay of the intracellular free Ca'++ transient.

scholarly journals The Mechanochemistry of Cardiac Muscle

1967 ◽  
Vol 50 (4) ◽  
pp. 951-965 ◽  
Author(s):  
Peter E. Pool ◽  
Edmund H. Sonnenblick
Keyword(s):  
Cardiac Muscle ◽  
Adenosine Triphosphate ◽  
Papillary Muscle ◽  
Coupling Efficiency ◽  
Creatine Phosphate ◽  
Energy Utilization ◽  
Contractile Element ◽  
Cat Papillary Muscle ◽  
Net Production ◽  
Mechanochemical Coupling

The utilization of creatine phosphate (CP) and adenosine triphosphate (ATP) was studied in the iodoacetate (IAA) and nitrogen (N2)-treated cat papillary muscle. Under these conditions the net production of ATP does not occur, and the net utilization of ATP is reflected in a fall in CP concentration. The rate of energy utilization of the IAA-N2-treated cat papillary muscle resting without tension was 0.68 µmole CP/g/min. This rate was increased to 1.07 µmole/g/min when muscles were passively stretched with 2 g of tension. In a series of isometrically contracting muscles CP utilization was found to be proportional to the number of activations and the summated contractile element work. These rates of CP utilization were 0.083 µmole/g/activation and 0.0059 µmole/g-cm of work. The calculated mechanochemical coupling efficiency was 33%.

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