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R Minelli

Publications and source records attributed to R Minelli.

At least 73 records · Page 4Linked to original sources
PubMed1978

Influence of internal shortening on time course of active state in rat papillary muscle.

In order to investigate internal shortening effects upon time course of active state, a study on rat papillary muscle has been carried out. Internal (or CE) shortening was evaluated according to a mechanical muscle model in which parallel elastic (PE), series elastic (SE), contractile (CE) elements are represented. CE force-velocity-shortening-time relationships have been used to describe time course of muscle active state in isometric, completely isotonic, afterloaded, and stopped isotonic contractions. The results obtained suggest that, regardless of type of contraction utilized, the parameters of muscle active state are strongly influenced by the amount of CE shortening.

Animals↗
PubMed1976

Myocardial contractility in aged rats.

The elastic and mechanical behaviour of isolated papillar muscle was studied in aged and in young rats. The spontaneous fall in tension (stress relaxation phenomenon) and the duration of the active state of the contractile element during the isometric and isotonic contraction were greater in aged than in young rats. The elastic properties of the elements in parallel and in series and the intensity of the active state in the contractile elements, on the contrary, did not exhibit any significant difference between aged and young rats.

Aging↗
PubMed1975

Cardiac muscle models for both isotonic and isometric contractions.

The choice of a suitable muscle model consistent with the mechanical behaviour of Rat papillary muscle at rest or during isotonic or isometric contraction has been considered. Three different preload levels within the ascending limb of the Frank-Starling curve have been used in five papillary muscles. Series elastic (SE) and parallel elastic (PE) length-tension relationships have been evaluated according to five mechanical muscle models using data from systolic and diastolic quick-release manoeuvres. For each preload level and muscle model, the time course of the force-velocity relationship of the contractile element (CE) has been calculated using a PDP 8/L digital computer. Several mechanical and biological characteristics are considered which exclude four of the five selected muscle models. The Maxwell model with a damper seems to be the most suitable mechanical model for Rat papillary muscle. According to the selected muscle model it seems that VCEmax is dependent on muscle length variation; the reliability of this parameter as an index of myocardial contractility is discussed.

Animals↗