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At least 217 records · Page 12Linked to original sources
PubMed1986

Real-time acquisition and data analysis of skeletal muscle contraction in a multi-user environment.

A data acquisition system is described which acquires data from contracting skeletal muscle. The system is designed to run in a multi-user environment while acquiring contractile data in real-time. Time dedicated solely to laboratory experiments is thus eliminated. A menu-driver is included to allow users to enter experimental commands with or without command arguments. Error monitoring functions prevent operator errors from causing data loss. Data storage in both ASCII and binary formats maximizes file flexibility, readability and accessibility. Finally, an on-line tutorial and help facility is provided for user training. The system developed is applicable to any experimental environment involving data acquisition, storage and analysis.

Animals↗
PubMed1987

Use of muscle contraction formalism for kinesin in fast axonal transport.

The general procedure is discussed for calculating the velocity of a vesicle along a microtubule. The formalism used previously for isotonic contraction in muscle (with multiple actin sites for a given cross-bridge) can be employed. However, some modifications must be made: (i) the kinetic diagram must include a state in which kinesin is absent from a vesicle binding site, (ii) an average must be taken over the locations of the vesicle binding sites relative to microtubule sites, and (iii) a self-consistency condition must be imposed that equates the mean force exerted by kinesin molecules on the vesicle with the frictional resisting force of the medium.

Animals↗
PubMed1993

On the regeneration of the actin-myosin power stroke in contracting muscle.

The transient behavior of muscle in double-or multiple-step length perturbations [Lombardi, V., Piazzesi, G. & Linari, M. (1992) Nature (London) 355, 638-641] is simulated with a "conventional" cross-bridge model, which has been reported [Eisenberg, E., Hill, T. L. & Chen, Y. (1980) Biophys. J. 29, 195-227] to account for many mechanical, as well as biochemical, muscle data. The quick recovery of tension after double- or multiple-length perturbations was calculated for the model without any readjustment of its original parameters. The regeneration rate of the quick tension recovery of the model is fast and comparable to that measured experimentally by Lombardi et al. For multiple-step "stair-case"-type length releases, the tension response reaches a steady-state shape after three or four steps, and the average ATP turnover is much slower than the regeneration of the quick tension recovery. Our simulation shows that the experimental findings of Lombardi et al. can easily be reproduced by this simple conventional cross-bridge model, in which the completion of one work-producing power stroke is coupled to the hydrolysis of one ATP molecule. Thus, to account for the data of Lombardi et al., there is no need to assume that cross-bridges can execute multiple power strokes per ATPase cycle, although cross-bridges may well be able to do so. The mechanism that underlies the fast regeneration of the quick tension recovery in the conventional model used here is discussed.

Actins↗
PubMed1990

Local oxygen supply and blood flow regulation in contracting muscle in dogs and rabbits.

1. Multiwire surface electrodes were used to measure local hydrogen clearance curves and tissues PO2 in the sartorius muscle in dogs under resting conditions and during stimulation of the muscle at 1, 2, 4, 8 and 20 Hz via the femoral nerve. Tissue oxygen supply was assessed by means of PO2 histograms; evaluation of the initial slopes of the hydrogen clearance curves enabled the measurement of capillary blood flow. 2. In a further model, the analysis of hydrogen clearance curves measured in the femoral vein using intravascular needle electrodes in rabbits enabled the distribution of blood flow to be evaluated both under resting conditions and during direct 2 Hz stimulation of the vastus medialis muscle. 3. Increased oxygen consumption, induced by stimulation, caused increases in capillary flow which were not necessarily accompanied by augmentation of femoral artery flow. 4. PO2 histograms provided no evidence of cellular anoxia even at the maximum level of oxygen consumption. 5. A two-compartment distribution of flow was measured under resting conditions, whereas only one compartment could be resolved during 2 Hz stimulation of the vastus medialis muscle in the rabbit experiments. A clear redistribution of flow was observed in the absence of any increase in total flow. 6. A model for oxygen-dependent regulation of capillary blood flow involving high-flow and normal-flow compartments is proposed.

Anesthesia, Intravenous↗