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Biomedical subjects

P E Pool

Publications and source records attributed to P E Pool.

At least 55 records · Page 3Linked to original sources
PubMed1967

The mechanochemistry of cardiac muscle. I. The isometric contraction.

The utilization of creatine phosphate (CP) and adenosine triphosphate (ATP) was studied in the iodoacetate (IAA) and nitrogen (N(2))-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-N(2)-treated cat papillary muscle resting without tension was 0.68 micromole CP/g/min. This rate was increased to 1.07 micromole/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 micromole/g/activation and 0.0059 micromole/g-cm of work. The calculated mechanochemical coupling efficiency was 33%.

Adenosine Triphosphate↗
PubMed1967

Influence of the thyroid state on the intrinsic contractile properties and energy stores of the myocardium.

The intrinsic contractile properties of isolated cat papillary muscles and myocardial high energy phosphate stores were examined at three levels of thyroid activity and correlated with hemodynamic measurements in the intact animal. In addition, the relationship of thyroid state to endogenous norepinephrine stores and myocardial responsiveness to certain inotropic interventions were studied. In muscles from hyperthyroid cats, the velocity of shortening and the rate of tension development were markedly augmented, while duration of active state was decreased, compared to euthyroid muscles. These findings occurred in the presence and absence of intact norepinephrine stores and over a wide range of temperature and contraction frequency. The opposite changes occurred in muscles from hypothyroid cats. Isometric tension was slightly higher in muscles from hyperthyroid and lower in muscles from hypothyroid cats. The inotropic response to both norepinephrine and strophanthidin varied inversely with the level of thyroid state and allowed all three groups of muscles to reach a common ceiling of isometric tension regardless of thyroid state. Creatine phosphate and adenosine triphosphate stores were intact at all three levels of thyroid state. Thus, the level of thyroid activity profoundly affects the intrinsic contractile state of cardiac muscle, independent of both norepinephrine stores and alterations in high energy phosphate stores, and, in addition, modifies the responsiveness of cardiac muscle to inotropic agents.

Adenosine Triphosphate↗