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.

scholarly journals ACTIVE STATE OF MUSCLE IN IODOACETATE RIGOR

1959 ◽  
Vol 42 (5) ◽  
pp. 865-881 ◽  
Author(s):  
George E. Mauriello ◽  
Alexander Sandow
Keyword(s):  
Bearing Capacity ◽  
Iodoacetic Acid ◽  
Active State ◽  
Apparent Absence ◽  
Load Bearing Capacity ◽  
Mechanical Responses ◽  
Ringer’S Solution ◽  
Velocity Relation ◽  
Force Velocity ◽  
Frog Sartorius

Frog sartorius muscles, equilibrated to 2 x 10-4 M iodoacetic acid-Ringer's solution and activated by a series of twitches or a long tetanus, perform a rigor response consisting in general of a contractile change which plateaus and is then automatically reversed. Isotonic rigor shortening obeys a force-velocity relation which, with certain differences in value of the constants, accords with Hill's equation for this relation. Changes in rigidity during either isotonic or isometric rigor response show that the capacity of the rigor muscle to bear a load increases more abruptly than the corresponding onset of the ordinarily recorded response, briefly plateaus, and then decays. A quick release of about 1 mm. applied at any instant of isometric rigor output causes the tension to drop instantaneously to zero and then redevelop, the rate of redevelopment varying as does the intensity of the load-bearing capacity. These results demonstrate that rigor mechanical responses result from interaction of a passive, undamped series elastic component, and a contractile component with active state properties like those of normal contraction. Adenosinetriphosphate is known to break down in association with development of the rigor active state. This is discussed in relation to the apparent absence of ATP splitting in normal activation of the contractile component.

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.

scholarly journals The force-velocity relation and stepwise shortening in cardiac muscle.

1982 ◽  
Vol 51 (1) ◽  
pp. 37-42 ◽  
Author(s):  
D V Vassallo ◽  
G H Pollack
Keyword(s):  
Cardiac Muscle ◽  
Velocity Relation ◽  
Force Velocity

Effects of Acidosis on Maximum Shortening Velocity and Force-Velocity Relation of Skinned Rat Cardiac Muscle

1994 ◽  
Vol 26 (5) ◽  
pp. 601-607 ◽  
Author(s):  
Lucio Ricciardi ◽  
Roberto Bottinelli ◽  
Monica Canepari ◽  
Carlo Reggiani
Keyword(s):  
Cardiac Muscle ◽  
Shortening Velocity ◽  
Velocity Relation ◽  
Force Velocity
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