Wyniki wyszukiwania - Biblioteka Nauki

1

Differences between properties of male and female motor units in the rat medial gastrocnemius muscle

100%

Celichowski J. , Drzymala H.

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nr 1

EN

Differences between motor units in hindlimb locomotor muscles of male and female Wistar rats were studied. The contractile and action potential properties of various types of motor units as well as proportions of these units in the medial gastrocnemius muscle were analyzed. Experiments were based on functional isolation and electrical stimulation of axons of single motor units. Composition of motor units was different for male and female subjects, with higher number of the fast fatigable and lower number of slow type units in male animals. The contraction and the half-relaxation times were significantly longer in male motor units, what might be due to differences in muscle size. Slower contraction of male motor units likely corresponds to lower firing rates of their motoneurons. On the other hand, no significant differences between sexes were observed with respect to force parameters of motor units (the twitch and the maximum tetanus forces), except the fast resistant units (higher force values in male muscles). The mass of the muscle was approximately 1.5 time bigger in male rats. However, the mean ratio of motor unit tetanus force to the muscle mass was almost twice smaller in this group, what indirectly suggests that muscles of male rats are composed of higher number of motor units. Finally, female muscles appeared to have higher fatigue resistance as the effect of higher proportion of resistant units (slow and fast resistant) and higher values of the fatigue index in respective motor unit types. The motor unit action potentials in female rats had slightly lower amplitudes and shorter time parameters although this difference was significant only for fast resistant units.

2

The effect of vasoconstrictors on oxygen consumption in resting and contracting skeletal muscle of the autologous pump-perfused rat hindlimb

84%

Hoy A. J. , Peoples G. E. , McLennan P. L.

Journal of Physiology and Pharmacology

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2009

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tom 60

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nr 3

155-160

EN

This study used a novel in vivo model to test the hypothesis that nutritive and non-nutritive blood flow distribution can still be observed under conditions of high vascular tone and oxygen delivery at rest and in metabolically active (twitch contracting) skeletal muscle. Experiments were performed in a constant flow autologous pump-perfused hindlimb in anaesthetised male Wistar rats. Agonists were tested at rest with a flow rate of 1ml•min-1, and during hindlimb muscle twitch contractions (sciatic nerve stimulation: 6V, 1Hz, 0.05ms, 3min) at a flow rate of 2ml•min-1. Oxygen consumption was determined from hindlimb venous and arterial blood samples. Resting perfusion pressure at 1ml•min-1 was 92±3 mmHg (N=15) and oxygen consumption was 0.41±0.05 µmol•min-1•g-1. Serotonin increased perfusion pressure and significantly decreased basal hindlimb oxygen consumption at rest. During acute muscle contraction this effect on oxygen consumption was diminished. Noradrenaline significantly increased perfusion pressure but had no significant effect on basal hindlimb oxygen consumption. Vasoconstriction that impacts upon muscle metabolism occurs in vivo, which potentially could be due to selective redistribution of blood flow. However, during muscle contraction local release of vasodilatory regulation can overcome exogenously-induced vasoconstriction. These results support the hypothesis that dual vascular pathways may explain differential vasoconstriction and how it impacts upon muscle metabolism.

3

Morphological specializations of Cheiromeles (naked bulldog bats; Molossidae) and their possible role in quadrupedal locomotion

84%

Schutt,Jr. W. A. , Simmons N. B.

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tom 03

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nr 2

EN

Two molossids, Cheiromeles torquatus and C. parvidens, display a number of morphological characteristics that appear unique among Chiroptera. In this study, adult specimens of both species (fluid-preserved and skeletons) were examined using a dissecting microscope and camera lucida. Several unique morphological features are described in detail for the first time with comments on their possible functions. These include a hallux (digit I) that is positioned at a right angle to digits II-V, a calcar that is bound to m. gastrocnemius, and a modified m. tensor plagiopatagii which appears to function like a drawstring to close a pair of subaxillary 'pouches'. The function of these structures and additional characteristics of the limbs appear related to terrestrial and arboreal locomotion exhibited by these bats.

4

Hindlimb swing, stance and step relationships during unrestrained walking in cats with lateral funicular lesion

84%

Gorska T. , Majczynski H. , Bem T. , Zmyslowski W.

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tom 53

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nr 1

5

Bilateral projection of neurones of the C6 segment to S1 and S2 segments of the spinal cord in the cat

84%

Krutki P.

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1997

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tom 57

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nr 1

6

Effect of hind limb conformation on claw disorders in dairy primiparous cows

67%

Olechnowicz J. , Jaskowski J. , Nowak W.

Bulletin of the Veterinary Institute in Puławy

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2010

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tom 54

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nr 3

EN

The objective of this study was to determine the effect of hind limb conformation on claw disorders and locomotion in primiparous cows. The cows, housed in tie stalls (n=68) and in free stalls (n=74), calved throughout the year 2008. Rear legs set rear view, rear legs set side view, and foot angle scores were given in a scale from 1 to 9. Locomotion scores were defined in a scale from 1 to 5. Cows with healthy hooves had straight rear legs in rear view and lower scores for rear legs side view than cows with hoof disorders in hind limbs.

7

The content of myosin heavy chains in hindlimb muscles of female and male rats

67%

Drzymala-Celichowska H. , Karolczak J. , Redowicz M. J. , Bukowska D.

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2012

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tom 63

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nr 2

8

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

67%

Krutki P. , Grottel K. , Mrowczynski W.

Acta Neurobiologiae Experimentalis

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1999

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tom 59

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nr 4

9

The age dependent effect of partial denervation of rat fast muscles on their activity

67%

Tyc F. , Slawinska U. , Vrbova G.

Acta Neurobiologiae Experimentalis

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1999

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tom 59

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nr 2

10

Hindlimb muscle activity during unrestrained walking in cats with lesions of the lateral funiculi

67%

Zmyslowski W. , Gorska T. , Majczynski H. , Bem T.

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tom 53

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nr 1