Biomedical subjects

J Celichowski

Publications and source records attributed to J Celichowski.

40 records · Page 3Linked to original sources

PubMed1990

Division of motor units in medial gastrocnemius muscle of the rat in the light of variability of their principal properties.

Ninety-seven motor units of medial gastrocnemius muscle of the rat were examined. Among the examined motor units, fast (F) and slow (S) units were distinguished on the base of the presence or absence of sag reflex in unfused tetanus, induced by stimulation at 40 Hz. The fatigue test, in turn, permitted to distinguish fast fatigable (FF) and fast resistant (FR) units. Fatigue index was calculated using two techniques, the results of which differed significantly from each other. The following basic features of motor units were examined: contraction time, half-relaxation time and twitch force. A more detailed analysis of all characteristics of the units disclosed that their classification into fast and slow units on the base of the sag test alone was unjustified. A more appropriate classification resulted when multiple properties of the units were considered. The distinguished types of the units differed significantly from each other in the examined properties. On the other hand, a significant individual variability in the properties was also shown to exist within each type of the units. Various characteristics of the motor units showed correlation with each other in the whole population of motor units and/or their individual types.

Animals↗

PubMed1990

The course of motor unit twitch in dependence on muscle stretching force. Studies on medial gastrocnemius muscle of the rat.

Studies were performed on 46 units of medial gastrocnemius muscles in 23 rats. In the examined population, three types of motor units were distinguished: fast fatigable (FF), fast resistant (FR) and slow (S) units. The studied muscle was stretched with force gradually increasing from 0.5 to 10 g. Most of FF units and some of FR units reached the highest twitch force when the muscle was stretched with 4 to 7.5 g. The remaining fast units and almost all slow units reached the highest twitch force at 10 g stretching of the muscle. In some fast units, twitch force even decreased slightly at stretching of the muscle with 10 g force. On the other hand, contraction time and half-relaxation time were getting prolonged in the whole process of stretching the muscle. Most pronounced changes in contraction time and half-relaxation time took place in S type units while the least pronounced ones - in FF type units. The prolongation of half-relaxation times in motor units of all three types was more pronounced than the prolongation of contraction times.

Animals↗

PubMed1988

Twitch force and action potentials of single motor units in medial gastrocnemius muscle of the rat.

On the basis of a sag test in unfused tetanus we classified fast and slow motor units (MUs) in medial gastrocnemius muscle of the rat. The following parameters of motor units were investigated: single twitch force, duration of the action potentials, maximum-minimum amplitude time (M-MAT), action potentials amplitude and their latencies after stimulus (to the onset of potentials) and the diameter of MU territory in muscle medio-lateral direction. Differences were found between fast and slow MUs in all of the properties. A correlation was found between MU twitch forces and the diameters of territories and amplitudes of action potentials in the whole investigated MU population, as well as between the duration and the M-MAT of the action potentials.

Action Potentials↗

PubMedDate not supplied

Spatial analysis of motor unit potentials of the rat medial gastrocnemius.

The spatial analysis of the potentials of single motor units of the rat medial gastrocnemius muscle evoked by stimulation of the fibres of split ventral roots was carried out with a bipolar electrode moving in the direction perpendicular to the longitudinal axis of the muscle fibres. During this movement of the electrode a variability was observed in the time of the biphasic potential from its maximum to minimum, and in the peak-to-peak amplitude of these potentials. The potentials recorded outside the territory of the motor unit had a lower amplitude in relation to the potentials from the territory of the unit. This made localization of the motor unit on the cross-section of the muscle possible. Differences in the duration of the potential from maximal to minimal amplitude (maximum-minimum amplitude time--M-MAT) of each investigated motor unit from successive recording sites reflected the number of fibres contributing to the action potential and the distance of the recording surface of the electrode from the zone of the motor end-plates of this motor unit. The greatest diameter of the territory of the observed motor units reached 2.5 mm.

Action Potentials↗