Contractility and Conformation

Contractility and Conformation

Contractility in fibers can arise from changes of macromolecular conformation caused by changes in some thermodynamic variable such as temperature, pH, or solvent composition. Illustrations are given of contractile processes in fibers and of changes in macromolecular conformation in dilute solution. These may involve order-disorder transitions, e.g. of the type exhibited by the helix-coil trans...

[Contractility].

Cardiac work and contractility.

It has been customary to regard the heart as a pump maintaining the flow of blood, and to assess the work done by the heart from the pressure and volume of blood leaving the ventricles. While correct in physical terms, measurement of external cardiac work in this way is a poor index of the myocardial oxygen consumption which is related to the work done by the ventricular muscle. Systolic pressu...

Lymphatic Contractility

The most peripheral lymphatic vessels of rats, mice, and guinea pigs were found to possess a spontaneous intermittent contractility. (a) The rate of contraction was shown to be directly proportional to the rate of formation of lymph and contractions were apparently initiated by an increase in intraluminal pressure. (b) Epinephrine and pituitrin caused an increased contractile rate, or lymphatic...

Electrolytes and Arterial Muscle Contractility

THAT changes in ionic gradients affect contractility and excitability has been shown in skeletal muscle,' cardiac muscle' ° and nerve." The reduction of external sodium causes reduction and eventual loss of excitability in nerve and skeletal muscle, supposedly because depolarization is due to the entry of sodium into the cell. The precise effect of alterations in external sodium on contractilit...