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1

Cervical projections of neurones located in the second sacral segment of cats spinal cord

100%
Mrowczynski W.
Acta Neurobiologiae Experimentalis
|
1995
|
tom 55
|
nr 5
2

Lamina IV-VI neurones of the second sacral segment projecting to the sixth cervical segment of the cat's spinal cord

100%
Mrowczynski W.
Acta Neurobiologiae Experimentalis
|
1997
|
tom 57
|
nr 3
3

Projection of neurones located in sacral spinal cord segments to the cerebellum and the inferior olive in the cat

63%
Mrowczynski W., Krutki P.
Acta Neurobiologiae Experimentalis
|
2001
|
tom 61
|
nr 3
4

Physiological adaptations of motor units to endurance and strength training

63%
Mrowczynski W., Lochynski D.
Trends in Sport Sciences
|
2014
|
tom 21
|
nr 3
The motor units consisting of motoneuron and muscle fibers, is the smallest functional unit of the neuromuscular system, which has ability to adopt plastically to acting stimuli. The increase of the physical activity, evoked by various type of trainings is one of the most important factors which induces morphological, biochemical and physiological changes in motor units. Endurance and strength training are two forms of physical activity leading to differential modifications in physiological features of motor units. Endurance training improves ability of muscle to sustain contractile activity for a long time, while strength training improves muscle strength and power. This manuscript summarizes the knowledge on the essential physiological adaptations in the both components of motor units – motoneuron and muscle fibers to endurance and strength training. The main aim of this paper is to enhance understanding on the strategy by which the neuromuscular system optimizes its activity in order to improve capabilities of the skeletal muscles to both forms of physiological activity.
5

Electrophysiological investigation of spino-olivary projections originating from sacral segments of the cat spinal cord

63%
Mrowczynski W., Krutki P.
Acta Neurobiologiae Experimentalis
|
2001
|
tom 61
|
nr 4
6

Afferent input from distal forelimb nerves to branching spinoreticular-spinocerebellar neurones in the cat

63%
Krutki P., Mrowczynski W.
Acta Neurobiologiae Experimentalis
|
2002
|
tom 62
|
nr 4
7

Effects of progressive weight lifting training on motor unit contractile properties

51%
Lochynski D., Kaczmarek D., Mrowczynski W., Celichowski J.
Acta Neurobiologiae Experimentalis
|
2013
|
tom 73
|
nr Suppl.1
Strength training increases muscle strength and contractile speed. The purpose of the study was to examine basic motor unit (MU) contractile properties of medial gastrocnemius muscle after 5 week progressive strength training in adult rats. Three and half mo rats were randomly assigned to the two groups: untrained control and progressive weight lifting (PWL). Conditioned by food reward PWL rats performed “squat-rise to toes-squat” type exercises 5 days/week in the custom made apparatus, which intensity grew from 70 up to 85% of one-repetition maximum during applied training period. MUs were functionally isolated by ventral root filament splitting, and classified according to the fatigue index and “sag” property into slow (S), fast resistant to fatigue (FR) and fast fatigable (FF). For analysis, the peak force of the maximum tetanic contraction and the peak force and the contraction and relaxation times of the twitch were studied. The peak tetanus force increased in S and FR MUs. The twitch contraction time was shortened and the twitch-to-tetanus force ratio decreased in FF and FR MUs. These initial data indicate that a short-term PWL increases force of S and FR MUs and speed of contraction of fast MUs within fast-twitch skeletal muscle.
8

Double stimulation modulates afterhyperpolarization phase following action potentials evoked in rat motoneurones

51%
Mrowczynski W., Krutki P., Celichowski J.
Acta Neurobiologiae Experimentalis
|
2007
|
tom 67
|
nr 4
The influence of a pair of stimuli running in time sequence between 5–10 ms (a doublet) on the basic parameters of antidromic action potentials was studied in rat motoneurones. Electrophysiological experiments were based on stimulation of axons in the sciatic nerve and intracellular recording of antidromic action potentials from individual motoneurones located in L4–L5 segments of the spinal cord. The following parameters were analyzed after application of a single stimulus and a doublet: amplitude and duration of the antidromic spike, amplitude, total duration, time to minimum, half-decay time of the afterhyperpolarization (AHP). It was demonstrated that application of a pair of stimuli resulted in: (1) a prolongation of action potentials, (2) a prolongation of the total duration and half-decay time of the AHP, (3) a decline of the time to minimum of the AHP, (4) an increase of the AHP amplitude of the spike evoked by the second stimulus. Significant differences in AHP parameters were found either in fast or slow motoneurones. We suppose that doublet-evoked changes in the AHP amplitude and duration are linked to intrinsic properties of individual motoneurones and may lead to the prolongation of the time interval to subsequent motoneuronal discharges during voluntary activity.
9

Long-lasting effects of trans-spinal direct current stimulation on motoneuron firing properties in rats

51%
Krutki P., Drzymala-Celichowska H., Mrowczynski W., Baczyk M.
Acta Neurobiologiae Experimentalis
|
2019
|
tom 79
|
nr Suppl.1
INTRODUCTION: Trans-spinal direct current stimulation (tsDCS) is a neuromodulative technique used to improve motor functions in neurological disorders and to facilitate sport performance. However, despite the broad application of spinal cord polarization, the physiological mechanisms behind the observed effects remain unclear. We have recently demonstrated that anodal or cathodal tsDCS can alter motoneuron membrane properties and firing characteristics during its application and beyond. AIM(S): The aim of this study was to determine whether these alterations persist over a longer period of time. METHOD(S): The study was performed on adult male Wistar rats under general anesthesia. Anodal or cathodal tsDCS (0.1 mA, 15 min) was applied through an electrode located on the lumbar vertebra above the recording site. The intracellular recordings from L4‑L5 spinal motoneurons were performed at various periods after the offset of polarization (up to 3 hours). The animals not subjected to tsDCS formed the control group. RESULTS: Anodal tsDCS evoked a significant decrease in the voltage threshold, the rheobase, the threshold for rhythmic steady-state firing, as well as, an increase in the steady‑state firing frequencies and the slope of the frequency‑current relationship. Some of these modulatory effects were observed up to 60 minutes after the offset of polarization. Cathodal tsDCS induced only modest changes in motoneuron threshold properties, which could be observed no longer than 30 minutes after the end of polarization. CONCLUSIONS: This study for the first time provides the direct evidence that tsDCS evokes long-term alterations in the threshold and rhythmic firing properties of spinal motoneurons. Modulatory effects of anodal polarization are stronger and last longer than those of cathodal tsDCS. We suppose that both autonomous cell mechanisms and synaptic effects contribute to the occurrence and long-term persistence of the indicated changes in motoneuron properties. FINANCIAL SUPPORT: Supported by the National Science Center grant No 2017/25/B/NZ7/00373.
10

Changes in afterhyperpolarization after double stimuli in rat motoneurones

51%
Mrowczynski W., Krutki P., Celichowski J.
Acta Neurobiologiae Experimentalis
|
2007
|
tom 67
|
nr 3
11

The spinoreticular neurones in the second sacral segment of the cat's spinal cord

51%
Huber J., Grottel K., Krutki P., Mrowczynski W.
Acta Neurobiologiae Experimentalis
|
1995
|
tom 55
|
nr 5
12

Neurones in the cervical enlargement of the cat spinal cord with collaterals ascending to the inferior cerebellar peduncule and descending to sacral segments

51%
Mrowczynski W., Grottel K., Krutki P.
Acta Neurobiologiae Experimentalis
|
1999
|
tom 59
|
nr 3
13

Force-frequency relationship of rat and cat motor units in the medial gastrocnemius muscle

51%
Mrowczynski W., Celichowski J., Krutki P.
Acta Neurobiologiae Experimentalis
|
2005
|
tom 65
|
nr 3
14

Doublet of action potentials evoked by intracellular injection of current into rat motoneurones

51%
Mrowczynski W., Krutki P., Celichowski J.
Acta Neurobiologiae Experimentalis
|
2009
|
tom 69
|
nr 3
Experiments were based on electrophysiological method of direct stimulation and recording from motoneurones located in L4–L5 segments of the rats spinal cord. Records from spontaneously fi ring motoneurones were collected after intracellular application of a current of gradually increasing intensity. Current threshold for generation of the fi rst action potential was determined. Additionally, intervals between six fi rst potentials were analyzed. It was demonstrated that the gradually increasing current intensity caused the generation of doublets in 68% of motoneurones studied. Doublets appeared when stimulating current increased to 120–500% of the threshold value. Moreover, the appearance of the doublet resulted in a signifi cant prolongation of time interval to the subsequent, third action potential. These results suggest that doublets in motoneuronal fi ring appear as a result of their strong synaptic excitation. The prolonged interpulse interval after the doublet fi ring can be due to an increase of duration and amplitude of afterhyperpolarization (AHP), previously observed in antidromic doublet stimulation.
15
Content available remote

Interspecies differences in the force-frequency relationship of the medial gastrocnemius motor units

51%
Mrowczynski W., Celichowski J., Krutki P.
Journal of Physiology and Pharmacology
|
2006
|
tom 57
|
nr 3
Single, functionally isolated motor units were studied in the medial gastrocnemius (MG) muscle of cats and rats. Axons of their motoneurons were stimulated with trains of pulses at frequencies increasing from 1 to 150 Hz and forces developed by muscle fibers were measured and force-frequency curves were compared between species. The following observations were made: (1) the most steep parts of curves (related to unfused tetani of motor units) begun at lower frequencies of stimulations in all types of feline motor units, (2) for fast motor units, the same relative values of force of unfused tetani were achieved at significantly lower frequencies of stimulations in the cat than in the rat. Twitch time parameters of both species influenced the course of force-frequency curves. It was showed that the contraction times of feline units varied in the wide range (21-81 ms), and these units reached 60% of the maximum force at stimulation frequencies between 10 and 38 Hz. On the other hand, contraction times of rat units ranged from 10 to 34 ms, whereas stimulation frequencies necessary to reach 60% of the maximum force varied considerably, from 12 to 65 Hz. The correlations between the above parameters were found for motor units of each species. However, the regression lines drown for the collected population of cat and rat units did not form linear continuity. Thus it seems that interspecies differences in the twitch contraction times do not fully explain different force-frequency relationships in mammalian skeletal muscles.
16

Divergence of lamina VII and VIII neurones of S1 and S2 segments of the cat's spinal cord to the cerebellum and the reticular formation

51%
Krutki P., Grottel K., Mrowczynski W.
Acta Neurobiologiae Experimentalis
|
1999
|
tom 59
|
nr 2
17

Projections of laminae IV-VI neurones located in the S2 segment of the spinal cord to the C6 segment and the cerebellum in the cat

51%
Mrowczynski W., Grottel K., Krutki P.
Acta Neurobiologiae Experimentalis
|
1998
|
tom 58
|
nr 2
18

Branching neurones in the cervical spinal cord with axons that reach sacral segments and the lateral reticular nucleus. An electrophysiological study in the cat

51%
Krutki P., Grottel K., Mrowczynski W.
Acta Neurobiologiae Experimentalis
|
1999
|
tom 59
|
nr 4
19

Properties of rhythmic firing of motoneurons are altered in response to weight-lifting training in rats

45%
Krutki P., Mrowczynski W., Baczyk M., Lochynski D., Celichowski J.
Acta Neurobiologiae Experimentalis
|
2017
|
tom 77
|
nr Suppl.1
INTRODUCTION: Repeated short-term and high--intensity exercises with a progressive external load are defined as strength or resistance training, which is responsible for an increase in muscle mass and force. AIM(S): The aim of this study was to determine whether strength training induces adaptive changes in firing properties of motoneurons (MNs) innervating the trained muscles. METHOD(S): The study was performed on adult male Wistar rats. Animals from the training group were subjected to a five‑week voluntary progressive weight‑lifting program, while control rats were restricted to standard cage activity. Intracellular recordings from lumbar spinal MNs innervating gastrocnemius and soleus muscles were made under pentobarbital anesthesia. RESULTS: The strength training evoked adaptive changes in both slow and fast-type MNs, indicating their increased excitability: a higher input resistance, a lower rheobase, a decrease in the minimum currents required to evoke rhythmic firing. The maximum frequencies of the early‑state firing (ESF) and of the steady‑state firing (SSF) were increased. Moreover, higher ESF and SSF slopes of the frequency-current relationship were observed in MNs of the trained group. Higher maximum firing rates of MNs as well as higher discharge frequencies evoked at the same level of intracellular depolarization current imply higher levels of tetanic forces developed by motor units over the operating range of force production after the strength training. CONCLUSIONS: This study provides evidence that the changes in spinal excitability following strength training observed in humans may be due to changes in the intrinsic properties of the MNs. The findings largely explain why some adaptations in the twitch and tetanus force development of motor units could be observed in response to the dynamic resistance training without qualitative changes in the muscle myosin heavy-chain expression. FINANCIAL SUPPORT: The study was supported by the National Science Center grant 2013/11/B/NZ7/01518.
20

Changes in electrophysiological properties of rat hindlimb spinal motoneurons evoked by the whole body vibration

45%
Mrowczynski W., Baczyk M., Haluszka A., Celichowski J., Krutki P.
Acta Neurobiologiae Experimentalis
|
2013
|
tom 73
|
nr Suppl.1
The whole body vibration training was performed on adult male Wistar rats. The experimental group subjected to a whole body vibration consisted of seven rats, while the control group of nine rats. The training program included 5 weeks and was applied by 5 days a week. Each daily session consisted of four 30-s runs of vibration at 50 Hz. Intracellular properties of motoneurones were investigated during experiments on deeply anesthetized animals. It was demonstrated that a whole body vibration evoked adaptations in excitability and firing properties of fast-type motoneurons, exclusively. A significant decrease in rheobase current and a decrease in the minimum and the maximum currents required to evoke steady-state firing in motoneurons were revealed. These changes resulted in a leftward shift of the frequency-current relationship, combined with an increase in slope of this curve. These results showed that fast motoneurons of rats after vibration have the ability to produce series of action potentials at higher frequencies in a response to the same intensity of activation. Obtained data provided direct evidence on motoneuronal plasticity following a whole body vibration.
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