The effects of changing loading conditions and inotropic state on maximum isotonic lengthening rate (+dL/dt, muscle lengths/sec) were examined in isolated rat myocardium. Physiologically sequenced contractions were studied in 18 left ventricular papillary muscle preparations (stimulation rate, 12/min). To study the effects of changing loading conditions, only one loading variable (preload, tota...

The potential role of active state maintenance as a determinant of myocardial oxygen consumption (MVO2) has not been defined. Right ventricular papillary muscles from 15 cats were studied in a polarographic myograph at 23 degrees C in a Krebs-Ringer solution containing 7.5 mM Ca2+ and 10 mM caffeine. MVO2 was determined for isometric tetani at Lmax of 1-5 seconds' duration. Increases in tetanus...

We compared two sets of loading conditions for their effect on the mechanical performance of isolated rat trabecular muscle: (1) loading which approximated that of the intact ventricle; (2) nonphysiological afterloaded isotonic contractions. Improved performance, manifested by increased shortening and rate of shortening at constant load, was seen when lengthening occurred at light loads, as in ...

OBJECTIVE To demonstrate the muscle strength characteristics of shoulder internal and external rotators and the effects of isokinetic exercise on muscle activity in patients with adhesive capsulitis. DESIGN Cohort study with control subjects. PARTICIPANTS Eight patients with adhesive capsulitis and 8 controls. METHODS Maximal isometric and isokinetic strength tests of shoulder internal an...

This study addresses a long-standing controversy on the effects of the degree of activation on cross-bridge kinetics in vivo, by utilizing isolated intact and skinned fiber preparations. Steady force levels ranging from 0.1 to 0.76 P0 were achieved at 0 degrees C with temperature-step stimulation of intact fibers by varying the amount of caffeine in the bathing medium. The speed of unloaded sho...

This model was developed for the study of excitationcontraction coupling for single cardiac cell. The basic assumptions are following: depolarization of cellular sarkolemma (membrane) rises inward calcium current Is , which rises the level of sarcoplasmatic calcium but also induces release of calcium from cisternal sarcoplasmic reticulum. These two basic sources increase the level of sarcoplasm...

AIMS There are many biological investigations for determining an effective cure for the dysfunction of gastrointestinal tracts, using herbal medicine. It has been reported that Carum Copticum is a bactericidal agent and possesses anticholinergic, antihistaminic and b-adrenergic stimulatory effects in some tissues. However, these effects of Carum Copticum on mechanical activities of isolated int...

OBJECTIVE Many biological studies have been done to determine the activity of medicinal plants on gastrointestinal function. Since acetylcholine is the major transmitter involved in the gastrointestinal motility and there are some evidences regarding the cholinergic modulatory effect of hops extract, in the present study spasmolytic and antispasmodic action of hops (Humulus lupulus) on acetylch...

Introduction: Thymol has negative ionotropic effect on heart and has direct effect on calcium release from sarcoplasmic reticulum. Some of the herbal plants just like carum copticum consist of thymol. The postganglionic neurons of the gastrointestinal parasympathetic system are located mainly in the myenteric and submucosal plexuses. Stimulation of these parasympathetic nerves causes general in...