The present study examines the efficacy of the exercise electrocardiogram using the isotonic bicycle ergometer and isometric handgrip in predicting the extent of coronary obstructive disease, coronary collaterals, and abnormalities of left ventricular contraction (asynergy) in 65 patients. Of 32 patients with a normal isotonic exercise electrocardiogram, 25 had a normal coronary arteriogram (78...

To investigate the possible role of an alteration in excitation-contraction coupling in cardiac hypertrophy, we compared simultaneously recorded action potentials along with isometric or isotonic contractions of normal and hypertrophied papillary muscles. Hypertrophy was produced by renal hypertension in rats. Hypertrophied papillary muscles were taken from rats that had been hypertensive for 1...

Force and length steps, applied to a muscle fiber in the isometric state, are believed to synchronize attached cross-bridges. This alleged synchronization facilitates the interpretation of the experiments. A rapid force step elicits an elastic response of the attached cross-bridges, followed by an isotonic phase. The decay of this second isotonic phase is of the first order. This excludes that ...

Strength is a fundamental quality necessary in achieving optimal physical function and is defined as the ability to produce more force.(Siff M; Stone MH et al., 1993). Thus the display of strength has characteristics which include a magnitude, rate and direction. The force production can be measured by isotonic, isometric or isokinetic methods. The isotonic techniques require lifting a particul...

PARMLEY, WILLIAM W., AND LEONARD CHUCK. Length-dependent changes in myocardial contractile state. Am. J. Physiol. 224(5) : 11951199. 1973.-The present study describes an alteration of myocardial contractile state which is intimately associated with changes in muscle length. Seventy-one right ventricular cat papillary muscles were studied isometrically or isotonically in vitro. When muscle lengt...

In the labouring uterus, millions of myocytes forming the complex geometrical structure of myometrium contract in synchrony to increase intrauterine pressure, dilate the cervix and eventually expel the foetus through the birth canal. The mechanisms underlying the precise coordination of contractions in human myometrium are not completely understood. In the present study, we have characterized t...

Threads of contractile proteins were formed via extrusion and their isometric tensions and isotonic contraction velocities were measured. We obtained reproducible data by using a new and sensitive tensiometer. The force-velocity curves of actomyosin threads were similar to those of muscle, with isometric tensions of the order of 10g/cm2 and maximum contraction velocites of the order of 10(-2) l...

Isometric, afterloaded and isotonic contractions of cat right ventricular papillary muscle were studied in vitro at 30°C or 37°C. The length to which muscle contracted under a given total load varied directly with initial muscle length. The discrepancies between contracted muscle lengths depended upon load and the inotropic state of the muscle. In control contractions at 12/min, the maximum dis...

This article provides models and code for numerically simulating muscle-fluid-structure interactions (FSIs). This work was presented as part of the symposium on Leading Students and Faculty to Quantitative Biology through Active Learning at the society-wide meeting of the Society for Integrative and Comparative Biology in 2015. Muscle mechanics and simple mathematical models to describe the for...

Extract prepared from aerial part of Pycnocycla spinosa is a relaxant of rat ileum contractions. The objective of this research was to study the spasmolytic activity of P. spinosa root extract for comparison with the aerial part extract. Hydroalcoholic extracts were prepared by percolation method. A portion of rat ileum was removed and suspended under 1 g tension in Tyrode's solution at 37 °C a...