scholarly journals Changes in the Contractile Activity and Reactivity to 5-HT of Smooth Muscles of Rats Following Total Body Irradiation with Accelerated Electrons

Folia Medica ◽  
2019 ◽  
Vol 61 (3) ◽  
pp. 411-418 ◽  
Author(s):  
Xenodochidis A. Charilaos ◽  
Raina G. Ardasheva ◽  
Veselin G. Popov ◽  
Natalia A. Prissadova ◽  
Valentin I. Turiyski ◽  
...  

Background: Besides its “classical” neurotransmitter function in the central and peripheral nervous systems, serotonin, or 5-hydroxytryptamine (5-HT) is also a local hormone in a number of tissues, including those of the GI tract. Radiation is known to be able to disrupt certain functions of the tract, modulated by 5-HT-signaling pathways, or the serotonin receptors themselves. Aim: The present investigation focused on clarifying the nature and extent of influence of an accelerated electron beam with energy of 9 MeV on the serotonergic mediation of healthy smooth muscle gastric tissue of rats following total body irradiation of the animals. Materials and methods: The study involved a control group and two experimental groups of animals exposed to 1 and 5 Gy, respectively, using Siemens Primus S/N 3561. Circular smooth muscle tissues were isolated from rats 1 hour and 18 hours after they were exposed to 1 and 5 Gy and also 5 days after irradiation from the rats that received a dose of 5 Gy in order to investigate the action of exogenous serotonin at increasing concentrations from 10-8 to 10-4 mol/l. The contractile reactivity of each group SM preparations was registered isometrically. Results: Electron beams with energy of 9 MeV did not damage the contractile apparatus of gastric SM of rats and had a stimulating effect on contractility resulting from rapidly developing processes (1 hour) or later occurring once (5 days). Conclusions: Difference was observed in the importance of the factors of received dose, lapse of time from irradiation to investigation of SM tissues, and exogenous 5-HT concentration for the changes in SM reactivity in serotonin-induced tonic and phasic responses.

2018 ◽  
Vol 315 (4) ◽  
pp. H756-H770 ◽  
Author(s):  
Asmaa M. Almohanna ◽  
Susan Wray

Hypoxic preconditioning, the protective effect of brief, intermittent hypoxic or ischemic episodes on subsequent more severe hypoxic episodes, has been known for 30 yr from studies on cardiac muscle. The concept of hypoxic preconditioning has expanded; excitingly, organs beyond the heart, including the brain, liver, and kidney, also benefit. Preconditioning of vascular and visceral smooth muscles has received less attention despite their obvious importance to health. In addition, there has been no attempt to synthesize the literature in this field. Therefore, in addition to overviewing the current understanding of hypoxic conditioning, in the present review, we consider the role of blood vessels in conditioning and explore evidence for conditioning in other smooth muscles. Where possible, we have distinguished effects on myocytes from other cell types in the visceral organs. We found evidence of a pivotal role for blood vessels in conditioning and for conditioning in other smooth muscle, including the bladder, vascular myocytes, and gastrointestinal tract, and a novel response in the uterus of a hypoxic-induced force increase, which helps maintain contractions during labor. To date, however, there are insufficient data to provide a comprehensive or unifying mechanism for smooth muscles or visceral organs and the effects of conditioning on their function. This also means that no firm conclusions can be drawn as to how differences between smooth muscles in metabolic and contractile activity may contribute to conditioning. Therefore, we have suggested what may be general mechanisms of conditioning occurring in all smooth muscles and tabulated tissue-specific mechanistic findings and suggested ideas for further progress.


2019 ◽  
Vol 13 ◽  
pp. 117906951882191 ◽  
Author(s):  
Rohit Manchanda ◽  
Shailesh Appukuttan ◽  
Mithun Padmakumar

As in other excitable tissues, two classes of electrical signals are of fundamental importance to the functioning of smooth muscles: junction potentials, which arise from neurotransmission and represent the initiation of excitation (or in some instances inhibition) of the tissue, and spikes or action potentials, which represent the accomplishment of excitation and lead on to contractile activity. Unlike the case in skeletal muscle and in neurons, junction potentials and spikes in smooth muscle have been poorly understood in relation to the electrical properties of the tissue and in terms of their spatiotemporal spread within it. This owes principally to the experimental difficulties involved in making precise electrical recordings from smooth muscles and also to two inherent features of this class of muscle, ie, the syncytial organization of its cells and the distributed innervation they receive, which renders their biophysical analysis problematic. In this review, we outline the development of hypotheses and knowledge on junction potentials and spikes in syncytial smooth muscle, showing how our concepts have frequently undergone radical changes and how recent developments hold promise in unraveling some of the many puzzles that remain. We focus especially on computational models and signal analysis approaches. We take as illustrative examples the smooth muscles of two organs with distinct functional characteristics, the vas deferens and urinary bladder, while also touching on features of electrical functioning in the smooth muscles of other organs.


1986 ◽  
Vol 251 (4) ◽  
pp. G538-G545 ◽  
Author(s):  
J. D. Cohen ◽  
H. W. Kao ◽  
S. T. Tan ◽  
J. Lechago ◽  
W. J. Snape

The membrane potential and contractile activity of colonic circular smooth muscle from New Zealand White rabbits were studied after the production of acute experimental colitis. Colitis was induced in the distal colon by rectal infusion of formaldehyde solution, followed by an intravenous bolus of soluble immune complexes. Despite active mucosal inflammation, there are only occasional inflammatory cells in the muscularis. Electrophysiological studies on tissue from control rabbits and rabbits with colitis were performed using double sucrose gap and intracellular microelectrode techniques. The resting membrane potential was lower (-44 +/- 3 mV) in muscle from rabbits with colitis compared with control animals (-54 +/- 2 mV) (P less than 0.02). Amplitude of the electrotonic potential after a hyperpolarizing current pulse was decreased (P less than 0.05) and the time constant was shortened (P less than 0.01) in muscle from animals with colitis compared with normal animals. Amplitude (13.1 +/- 2.3 mV) and maximum rate of rise (0.24 +/- 0.06 V/s) of the spike potential, initiated by a depolarizing current pulse, were decreased in muscle from animals with colitis compared with muscle from healthy animals (P less than 0.001). Isometric tension generation after electrical and chemical depolarization of the membrane or bethanechol administration was decreased (P less than 0.001) in muscle from colitic animals. These studies suggest 1) membrane resistance and membrane potential are decreased in muscle strips from animals with colitis; and 2) there is a disturbance in the electrical and mechanical response of these tissues after stimulation.


1999 ◽  
Vol 277 (1) ◽  
pp. G127-G136 ◽  
Author(s):  
Anne Epperson ◽  
Helena P. Bonner ◽  
Sean M. Ward ◽  
William J. Hatton ◽  
Karri K. Bradley ◽  
...  

Voltage-activated K+(KV) channels play an important role in regulating the membrane potential in excitable cells. In gastrointestinal (GI) smooth muscles, these channels are particularly important in modulating spontaneous electrical activities. The purpose of this study was to identify the molecular components that may be responsible for the KV currents found in the canine GI tract. In this report, we have examined the qualitative expression of eighteen different KV channel genes in canine GI smooth muscle cells at the transcriptional level using RT-PCR analysis. Our results demonstrate the expression of KV1.4, KV1.5, KV1.6, KV2.2, and KV4.3 transcripts in all regions of the GI tract examined. Transcripts encoding KV1.2, KVβ1.1, and KVβ1.2 subunits were differentially expressed. KV1.1, KV1.3, KV2.1, KV3.1, KV3.2, KV3.4, KV4.1, KV4.2, and KVβ2.1 transcripts were not detected in any GI smooth muscle cells. We have also determined the protein expression for a subset of these KV channel subunits using specific antibodies by immunoblotting and immunohistochemistry. Immunoblotting and immunohistochemistry demonstrated that KV1.2, KV1.4, KV1.5, and KV2.2 are expressed at the protein level in GI tissues and smooth muscle cells. KV2.1 was not detected in any regions of the GI tract examined. These results suggest that the wide array of electrical activity found in different regions of the canine GI tract may be due in part to the differential expression of KV channel subunits.


1996 ◽  
Vol 74 (2) ◽  
pp. 187-196 ◽  
Author(s):  
Jian-Ping Jin ◽  
Michael P. Walsh ◽  
Mary E. Resek ◽  
Gail A. McMartin

Calponin is a thin filament associated protein found in smooth muscle as a potential modulator of contraction. Five mouse monoclonal antibodies (mAbs CP1, CP3, CP4, CP7, and CP8) were prepared against chicken gizzard α-calponin. The CP1 epitopic structure is conserved in smooth muscles across vertebrate phyla and is highly sensitive to CNBr cleavage in contrast with the chicken-specific CP4 and the avian–mammalian-specific CP8 epitopes that are resistant to CNBr fragmentation. Using this panel of mAbs against multiple epitopes, only α-calponin was detected in adult chicken smooth muscles and throughout development of the gizzard. Western blotting showed that the calponin content varied among different smooth muscle tissues and correlated with that of h-caldesmon. In contrast with the constitutive expression of calponin in phasic smooth muscle of the digestive tract, very low levels of calponin were detected in adult avian tracheas and no calponin expression was detected in embryonic and young chick tracheas. These results provide information on the structural conservation of calponins and suggest a relationship between calponin expression and smooth muscle functional states.Key words: smooth muscle calponin, caldesmon, expression, development, chicken trachea.


2018 ◽  
Vol 46 (1) ◽  
pp. 7
Author(s):  
Semih Altan ◽  
Kaan Dönmez ◽  
Feray Altan ◽  
Fahrettin Alkan

Background: Recently, the role of inflammation triggered by handling of the intestine various gastrointestinal (GI) surgeries is generally accepted as the key event in postoperative ileus (POI). Because, prokinetics have been increased the smooth muscle contractions and may act by attenuating the inflammatory process in the GI tract, they have been used the treatment of POI in human and animals. There are many in vivo analysis techniques of GI motility. However, there have not yet been studied associated with the evaluation of the inflammatory response. Therefore, it was aimed to evaluate the efficiencies of 3 different prokinetics from inflammatory response during experimentally-induced POI.Materials, Methods & Results: Twenty healthy lambs (30-45 days old) were randomly assigned to four groups. In all groups, enterotomy was performed on the ileum. Erythromycin and metoclopramide were administered to the ERT and MET groups before the surgery, respectively, while lidocaine was administered to the LID group as bolus before and continuous rate infusion during the surgery. Physiological saline was administered to the lambs in control group as placebo before the surgery. Blood samples were collected before surgery (~30-45 min), at the end of surgery (0 h), and at the postoperative 1, 3, 5, 10, 48, 72 and 96 h. The concentrations of serum amyloid A (SAA), haptoglobin (HPT), fibrinogen (FIB) as acute phase proteins (APPs), thiobarbituric acide reactant substrate (TBARs), myeloperoxidase (MPO) as reactive oxygen species, and transforming growth factor-beta (TGF- β) as a cytokine were measured with ELISA reader. In terms of time points, it was found that FIB was statistically higher in ERT group at the 1st h, in MET and LID groups at the 10th h, and in LID group at the 48th and in MET group at the 72 h (P < 0.05). It was found that SAA was higher in MET group at the 1st, 3rd, 5th, 10th, 24th, 48th and 72nd h. HPT was higher in CNTR group until 72th h and MET group at 48th, 72nd and 96th h. TBARs concentrations were statistically higher in MET and LID groups at 0 hour, in ERT and MET groups at the 1st h, in MET group at the 3rd h, in MET and LID groups at the 5th and 10th h, in MET group at the 48th, 72nd and 96th h (P < 0.05). MPO concentrations was higher in LID group at the 3rd, 5th, 10th and 96th h, and in ERT group at the 72nd h (P < 0.05). TGF-β concentrations were particularly high in MET group at the 3rd, 5th, 48th and 72nd h, and in LID group at the 10th, 24th, and 96th h (P < 0.05).Discussion: APPs (HPT, SAA, FIB), which are important regulators of inflammation in cows and sheep, were higher generally in MET and LID groups and inflammation persists in these two groups and, therefore, metoclopramide and lidocaine are less effective in early postoperative POI treatment. Because, significant increase in serum TBARs and MPO concentrations was considered as an important indicator of oxidative stress and inflammatory response MPO concentrations was particularly high until 10th h in LID group, and TBARs concentrations was high both MET and LID groups throughout the study, this was correlated with higher neutrophil infiltration in the postoperative early period than the other groups. It is known that TGF-β, an inflammatory cytokine, is correlated with various smooth muscle disorders in humans. In this study, TGF-β concentration were higher in the MET and LID groups. High concentration of this cytokine might have led to decrease contractions in smooth muscles, thereby slowing down the intestinal transition. In conclusion, based on the presence of pro-inflammatory markers in this study, erythromycin seems to be the most suitable prokinetic drug in lambs. Moreover, lidocaine and metoclopramide are not as successful in small ruminants as reported in other species.


2021 ◽  
Vol 12 ◽  
Author(s):  
Susan Wray ◽  
Clodagh Prendergast ◽  
Sarah Arrowsmith

In smooth muscle tissues, calcium-activated chloride channels (CaCC) provide the major anionic channel. Opening of these channels leads to chloride efflux and depolarization of the myocyte membrane. In this way, activation of the channels by a rise of intracellular [Ca2+], from a variety of sources, produces increased excitability and can initiate action potentials and contraction or increased tone. We now have a good mechanistic understanding of how the channels are activated and regulated, due to identification of TMEM16A (ANO1) as the molecular entity of the channel, but key questions remain. In reviewing these channels and comparing two distinct smooth muscles, myometrial and vascular, we expose the differences that occur in their activation mechanisms, properties, and control. We find that the myometrium only expresses “classical,” Ca2+-activated, and voltage sensitive channels, whereas both tonic and phasic blood vessels express classical, and non-classical, cGMP-regulated CaCC, which are voltage insensitive. This translates to more complex activation and regulation in vascular smooth muscles, irrespective of whether they are tonic or phasic. We therefore tentatively conclude that although these channels are expressed and functionally important in all smooth muscles, they are probably not part of the mechanisms governing phasic activity. Recent knockdown studies have produced unexpected functional results, e.g. no effects on labour and delivery, and tone increasing in some but decreasing in other vascular beds, strongly suggesting that there is still much to be explored concerning CaCC in smooth muscle.


Author(s):  
A. M. Puzikov

Introduction: Serotonin (5-hydroxytryptamine, 5-HT) is a regulatory neurotransmitter and a hormone in the CNS and hole organs, the esophagus including. It is known that serotonin, activating its own receptors, stimulates contractile activity of the esophageal muscles. However, role of different type receptors in the 5-HT induced contractile activity of the esophagus is insufficiently known.The aim: — to determine which type of 5-HT receptors mediate serotonin dependent contractile activity of the esophagus.Material and methods: This is a electromyography study of rat esophagus contractile activity under serotonin stimulation of 5-HT3,4 and 5-HT2,1 receptors separately modulated. The role of different serotonin receptors in the 5-HT induced contractile activity of the esophagus was evaluated by measuring the amplitude and frequency of the slow wave electromyogram (EMG) by the noninvasive microelectrodes imposed on the adventitial layer of the esophagus.Results: Administration of the 5-HT3,4 receptors inhibitors excluded caused by serotonin the increment of EMG activity of the contractile activity of the esophagus. Administration of the 5-HT1,2 receptors inhibitors blocked the serotonin enhanced EMG activity of the esophagus.Conclusion: Our results indicate that serotonin is the important player in the regulation of the rat's esophagus contractility; 5-HT enhancing effect on contraction of the esophageal smooth muscles is mediated through the activation of 5-HT1,2 receptors expressed on the smooth muscle cells, and by activation of 5-HT3,4 receptors expressed on the ganglion neurons.


Author(s):  
P. Virych ◽  
O. Shelyuk ◽  
V. Martynyuk ◽  
V. Pavlovsky

The effect of compounds based on 3-substituted-1,4-benzodiazepine-2-ones on contractile activity of smooth muscles of the rat's stomach was analyzed. Action substances MX-1626, MX-1775 for the smooth muscle contraction of like competitive inhibitor of bradykinin – des-Arg9- [Leu8]-Bradykinin acetate, which is observed as increase normalized rate of contraction with increasing of bradykinin concentration and characterized by a slowdown in the first phase of contraction. The most effective 3-subtituted 1,4-benzodiazepin-2-ones was at low concentrations of bradykinin, increasing it concentration their effect is reduced.


2009 ◽  
Vol 8 (4) ◽  
pp. 41-46
Author(s):  
I. V. Kovalyev ◽  
S. V. Gusakova ◽  
O. S. Melnik ◽  
M. B. Baskakov ◽  
L. V. Kapilevich ◽  
...  

The influence of of hydrogen peroxide on the contractile reactions of smooth muscle cells caused by hyperpotassium solution end phenylephrine in modulation a potassium conductance the membrane and the state of cytoskeleton elements has been investigated by the mechanographical method. It has multidirectional influence of hydrogen peroxide in the reduction of smooth muscles of rat aorta with the membrane depolarization hyperpotassium solution and action phenylephrine: phenylephrine decline in value and increase strength hyperpotassium contractures. We show that the cytoskeleton components involved in the mechanisms of action of hydrogen peroxide in the contractile reactions of smooth muscles of rat aorta caused by phenylephrine.


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