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Protein sensibilisation has different effect on the contractile function of «fast» and «slow» skeletal muscles of a mouse in vitro
Teplov Alexander Yurievich, Kazan State Medical University, Associate Professor, Department of Pathology E-mail: Alikteplov@mail.ru Farkhutdinov Albert Mansurovich, Kazan State Medical University, Senior Teacher, Department of Pathology E-mail: Am_farkhutdinov@mail.ru
Protein sensibilisation has different effect on the contractile function of «fast» and «slow» skeletal muscles of a mouse in vitro
Abstract: The work analyzes the impact of allergic transformation of the organism on the contractile function of isolated skeletal muscles (SMs) of the lower leg of a mouse. It is shown that both «fast» (m. EDL) and «slow» (m. soleus) SMs change their contractile properties during protein sensibilisation (PS). The vector of change of strength and pace of contraction both at cholinomimetic carbacholinum (CC) and at KCl in the conditions of PS for muscles with different phenotype is of diverse nature. There is a presupposition that changes of the contractile function of SMs are determined by both changes of choline mediated processes of activation of a membrane of muscle fibers (MFs) and changes in the system of electromechanical connection (EMC).
Keywords: Skeletal muscles, contractile properties, protein sensibilisation.
It is well known that allergic transformation of the organism is accompanied by a change of morphofunctional state of skeletal muscles (SMs) of homoithermic animals [1]. One of the mechanisms ensuring the development of adaptive processes in the tissues and organs during the allergic transformation of the organism is a change of potassium-dependent processes of cell activation [2]. On the other hand, variability of functions of the muscle system is one of the brightest manifestations of these processes. And, if mechanisms, including potassium-mediated ones, of functional variability of smooth muscle organs, primarily airway, during an allergy are studied quite in detail, the questions of flexibility of SMs in the above mentioned conditions remain absolutely unstudied. The relevance of the given problem is determined by undiscovered mechanisms of compensatory changes in the operation of motor muscles during compulsory vaccination of sportspeople before the competition.
The objective of the work is to study mechanisms of impact of protein sensibilisation (PS) on the contractile response of different isolated muscles of the lower leg of a mouse: «fast» (extensor digitorum longus — m. EDL) and «slow» (solei — m. soleus) provoked by humoral agents — cholinomimetic carbacholinum (CC) and potassium chloride (KCl).
Materials and methods: The experiments were performed on mice of both sexes with the mass of the body 17-22 g. The animals were sensibilized twice by ovalbumin (OVA) with the gel of aluminum hydroxide (2 mkg. of dry gel substance + 150 mkg. of OVA in 0,5 ml. of physiological solution) abdominally [3]. The second injection was given in 14 days after the first one. The animals were selected for the experiment at the peak of sensibilisation — on 7-10th day after the second sensibilising injection. Mechanomyographic studies were conducted on the medication of an isolated muscle in the
conditions of isometry, which was achieved by stretching of the medicine of the muscle during 20 minutes with the force of 0,5 g. at the constant perfusion by a Krebs solution. The contraction was registered by the force meter. Agonist ChC was studied in the concentrations from 2 х 10-5 M to 3 х 10-3 M. KCl was studied in the concentrations from 50 to 250 mmol/l. The contractile function was analyzed according to the indicators of contractions of muscles to ChC and KCl. The power (Рос) and velocity (Voc) of muscle contraction to the substances in submaximal and maximal concentrations were estimated.
The contraction of isolated SMs to the increase of concentration of ions К+ is a convenient «test» to study EMC processes [7], and it allows defining the role of choline-mediated processes in the mechanisms of activation of MFs of membrane when comparing with the contractile response to ChC. This role can be determined quantitively as a correlation of maximal power that the muscle can develop at the contraction to ChC to maximal power developed at the contraction
to ChC (PChCmax/PKClmax).
Results. It was shown that ChC in submaximal concentration (7 х 10-4 M) activated the contraction of m. EDL of a non-sensibilized mouse with the power of 76,6 + 6,1 mg. and velocity of 14,3 + 1,6 mg/sec. At PS, the power of contraction of the fast muscle reduced to 61,9 + 12,2 mg. and the velocity almost didn’t change — 13,6 + 4,1 mg/sec.
In the soleus muscle of a non-sensibilized mouse, ChC in submaximal concentration (5 х 10-4 M) activated the contraction of the power of 237,8 + 20,6 mg and velocity of 13,1 + 1,0 mg/sec. PS lead to the increase of power — 353,2 + 23,1 mg. (p < 0,01) and velocity — 16,6 + 1,5 mg/sec of the contraction of the slow muscle.
The power of contractile responses of m. EDL to maximal concentrations ofthe agonist (4 х 10-3 M) and KCl (250 mmol/l)
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Section 4. Medical science
had the following values in the control group: 103,83 + 15,70 mg.
and Ш,69 + 6,73 mg. ^ChCmAdmax — 75,9 %) at PS became 52,13 + 14,66 mg. (p < 0,05) and 142,72 + 23,83 mg.
(PChCmax/PKClmax — 36,5 /) reSPeCtiVelY, i. e. *e value of
PrY /P„„ — reduced to 48 / of the control at PS.
For the soleus muscle, the power of contractile responses to the agonist in maximal concentration (2 х 10-3 M) and KCl (150 mmol/l) that had the following values in the control group:
322,32 + 30,18 mg. and 643,23 + 69,59 mg. (PChCmax/PKClmx — 50,1 /) changed respectively to 475,14 + 52,66 mg. (p < 0,05)
and 1470,49 + 186,05 mg (p<0,01) (PchCmax/PKClmax — 32,3 /)
at PS, i. e. the value of P„ „ /PY„ reduced to 64,5 / from the control at PS.
Discussion. The analysis of the results shows the difference in the contractile function of «fast» and «slow» muscles of the lower leg of a mouse manifested in the differences of characteristics of their contractions to the agonist and KCl. Discovered functional variability has a morphological basis, which is confirmed by literature data. The difference in the power of contractions to ChC is directly connected to the composition of fibers, in our opinion. The soleus-like muscle contains 50-60 / of «slow» fibers, and m. EDL is 97-100 / made of «fast» ones [5]. Consequently, a big contraction power of the soleus muscle to ChC is the result of its bigger responsivity to cholinomimetic and is determined by a big number of choline-receptors (ChR) in the area of synapse. The sizes of the end plate in MFs of «slow» muscle is 3 times longer than in MFs of «fast» one (m. EDL) [4].
The functional differences of the studied SMs are confirmed by their contractions to KCl, which complies with the data of Dulhunty A. F. [8] and Lorcovich H. [9]. Working on lower leg’s muscles, these authors confirmed the presupposition stated by Zhukov E. K. [10] and Nasledov G. A. [11] claiming that the potassium contracture has its own peculiarities for every kind of MFs when characterizing the EMC system.
PS changes the functional properties of SMs of a mouse. Herewith, for «fast» and «slow» muscles, they differ in their orientation and quantitively. Considering the possible mechanisms of PS effect on functional and contractile properties of SMs, one should pay attention to the following aspects. According to literature sources, changes arising in MFs in the course of PS can affect the surface membrane [6], EMC mechanisms or the system of contractile proteins [1]. Differences in the mechanisms of a change of functional properties of «fast» and «slow» muscles at PS are confirmed by
the vector of power and velocity dynamics of the contractions to ChC in maximal concentration. The power and velocity of the «fast» muscle reduces. As for the «slow» muscle, its velocity also reduces but its power increases. Such dynamics certifies about changes of choline-mediated processes of activation of MFs membrane, but not EMC system ensuring Са 2+ dependent mechanisms of SMs contraction. Our experiments show that choline-mediated mechanisms of SMs activation are primarily subject to changes.
The use of the correlation of maximal power of carbo-choline and potassium contractions in the analysis proves the ability of PS to differently change contractile properties of muscles with different phenotype. In both cases the values of PChCmax/PKClmax reduced; however, it was more expressed for the «fast» muscle (reduction to 48,1 /) than for the «slow» one (reduction to 64,5 /). It is obvious that both noted facts: discovered effect of PS on the power of ChC-activated contraction in «soft» muscle unlike the «fast» one, and the ability to change the power of potassium contracture, have a common nature in their basis and determine the mechanisms of SMs flexibility. Apparently, discovered changes of contractile properties of SMs at PS primarily affect choline-mediated processes of MFs activation and are of a divergent character for «fast» and «slow» muscles.
The work presented a complex evaluation of a contractile function to a range of initiators of contraction in different concentrations that allows conducting an objective analysis of the condition of a contractile apparatus of an isolated mouse. Particularly, registration of a contraction to submaximal concentration of ChC showed quantitative differences in the mechanisms of effect of sensibilisation to choline-mediated processes of activation of «fast» and «slow» muscles. Including of the potassium contracture in the analysis enabled to presuppose the participation of other stages of SMs contraction in the mechanisms of their adaptation during an allergic transformation of the organism. Qualitative evaluation of these characteristics allowed establishing differences in the reaction of «fast» and «slow» muscles of a mouse in PS conditions. Determination of the level of participation of different stages of muscle contraction in the mechanisms of discovered changes requires further research.
Conclusion: Allergic transformation changes functional properties of SMs of a mouse affecting choline-mediated processes of activation of muscle fibers membrane and EMC mechanisms, which leads to significant differences in changes of «fast» and «slow» muscles.
References:
1. Guschin I. S. Anaphylaxis of smooth and cardiac muscles. - M.: Meditsina, - 1973, - 175 p.
2. Yuan P., Leonetti M. D., Hsiung Y., MacKinnon R. Open Structure of the Ca2+ Gating Ring in the High-Conductance Ca2+ - Activated K+ Channel. Nature, - 2011, - 481 (7379): 94-97.
3. Guschin I. S., Zebreva A. I., Bogush N. L. and others. Experimental model for the development and evaluation of ways to control immediate allergy. Pathological, physiological and experimental therapy. - 1986, - 4: 18-23.
4. Fahim M. A., Holley J. A., Robbins N. Topographic comparison of neuromuscular junctions in mouse slow and fast twitch muscles. Neuroscience - 1984, Sep; - 13 (1): 227-35.
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Disadaptation infants at high risk — the result of the negative impact of complicated pregnancy and childbirth
5. Florendo J. A., Reger J. F., Law P. K. Electrophysiologic differences between mouse extensor digitorum longus and soleus. Exp Neurol. - 1983, Nov; - 82 (2): 404-12.
6. Ado A. D., Stomakhina N. V., Tuluevskaya L. M., Fedoseeva V. N. Protein spectra and phospholipidic composition of membranes rich in choline-receptors from skeletal muscles of rats in the conditions of sensibilisation. Bul. experim. biol. medicine - 1984, - V. 99; - 7: 84-86.
7. Lawler J. M., Hu Z., Barnes W. S. Effect of reactive oxygen species on K+ - contractures in the rat diaphragm. J. Appl. Physiol. - 1998, - V. 84; - 3: 948-953.
8. Dulhunty A. F. Slow potassium contractures in mouse limb muscles. J. Physiol. - 1981, - 314: 91-105.
9. Lorcovich H. Potassium contractures in mouse limb muscles. J. Physiol. - 1983, - 343: 569-576.
10. Zhukov E. K. Essays on nervomascular physiology. - L: Nauka, - 1969, - 288 p.
11. Nasledov G. A. Tonetic muscular system of the vertebrata. - L: Nauka, - 1981, - 187 p.
Tumaeva Tatiana Stanislavovna, Mordovian Republican Clinical Perinatal Center, Head of the department of functional diagnostics E-mail: tstumaeva@mail.ru Naumenko Elena Ivanovna, Mordovia State University, Chair of Pediatrics, Assistant professor E-mail: ei-naumenko@yandex.ru
Disadaptation infants at high risk — the result of the negative impact of complicated pregnancy and childbirth
Abstract: The purpose of the study- the influence of adverse maternal factors violation postnatal adaptation of newborns at high risk. The study included 747 newborns (270 preterm), of which 440 children born by caesarean section. In the formation of neonatal disadaptation factors had the greatest significance burdened obstetric and gynecological history mothers (abortion, inflammatory diseases of female genitalia, nulliparous age older than 30 years in conjunction with various somatic and obstetric pathology), complicated pregnancy (growth retardation, threatened abortion, hemodynamic instability in the mother-placenta-fetus), intrapartum period (deterioration women extragenital pathology, preeclampsia, severe, chronic hypoxia and/or acute asphyxia, which started bleeding).
Keywords: risk factors for antenatal and intrapartum periods, caesarean section, premature, cerebral hypoxia-ischemia, neonatal disadaptation.
Relevance. Problems of women’s health in various stages of gestation, and the status of the developing fetus and newborn occupy one of the leading places in the modern health care. The most common cause of disability of the child population is diverse defeat the perinatal period [1; 2; 3]. In case of violation functioning of the various systems of the parent body, responsible for the development of adaptive changes during pregnancy, numerous physiological adaptive processes are imperfect [4; 5]. This promotes the formation of obstetric pathology (noncarrying, preeclampsia, anemia, etc.), exacerbation of chronic and/or manifestation of latent diseases. The risk of perinatal pathology increases the formation of pregnancy and childbirth complications leading to operative delivery [6; 7]. Modern techniques used in obstetrics and neonatology can not completely neutralize the effects of pathological factors on children from high-risk groups (preterm, born surgically, children who have suffered hypoxia-ischemia, etc.) [8; 9; 10]. In this regard, a detailed examination of pregnant women and the identification of risk factors are essential for the prevention
of complications of pregnancy, labor and perinatal pathology. Aim of this study was to evaluate the significance of risk factors for antenatal and intrapartum periods in the development of early adaptation disorders in infants at high risk for the development of perinatal pathology.
Patients and methods. A comprehensive clinical and instrumental study of health 690 newborns at risk in the early period of adaptation. The main group (I) of 290 children born by cesarean section and post-hypoxia-ischemia (120 full-term, 170 preterm). Comparison group-1 (II): 150 full-term infants after caesarean section with no signs of cerebral ischemia during the early adaptation. Comparison group-2 (III): 250 newborns from natural birth with the transfer of hypoxic-ischemic (150 full-term, 100 preterm). Exclusion criteria: children with congenital abnormalities, infectious processes, syndromic disorders. Control group (IV)-57 full-term newborns of physiological pregnancy and birth with Apgar score 8/8 points. To study the dependence disorders early neonatal adaptation processes at increased risk from exposure to pathological factors
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