{"id":59276,"date":"2024-06-25T10:28:46","date_gmt":"2024-06-25T10:28:46","guid":{"rendered":"https:\/\/biomedpharmajournal.org\/?p=59276"},"modified":"2024-07-03T17:50:47","modified_gmt":"2024-07-03T17:50:47","slug":"the-effect-of-ajuga-turkestanica-on-the-rat-aortic-smooth-muscle-ion-channels","status":"publish","type":"post","link":"https:\/\/biomedpharmajournal.org\/staging\/vol17no2\/the-effect-of-ajuga-turkestanica-on-the-rat-aortic-smooth-muscle-ion-channels\/","title":{"rendered":"The Effect of \u00c1juga Turkest\u00e1nica on the Rat Aortic Smooth Muscle Ion Channels"},"content":{"rendered":"\n

Introduction<\/strong><\/p>\n\n\n\n

Control of membrane potential\nand smooth muscle excitability and intracellular ion concentration is a process\ndependent on the activity of ion channels, in which voltage-gated Ca+<\/sup>\n(VGCC) channels, receptor-dependent (TRP) channels, and Ca2+<\/sup>-activated\nK+<\/sup> (BK) channels are the main regulators2<\/sup>.\nThe ability of vascular smooth muscles to contract regulates the work of\narteries. Several ion channels, voltage-gated Ca2+<\/sup> channels, and\nintracellular Ca2+<\/sup> channels regulate smooth muscle (SM) contraction\nby controlling membrane potential3<\/sup>.\nL-type Ca2+<\/sup> channels play an important role in the activity of SMCs.\nThe influx of Ca2+<\/sup> ions and the role of R-type channels are also\nimportant for SM contraction4<\/sup>. It has also\nbeen shown that these ion channels regulate SM excitability5<\/sup>.<\/p>\n\n\n\n

Material and methods<\/strong><\/p>\n\n\n\n

Chemicals<\/strong><\/strong><\/p>\n\n\n\n

 Ajuga turkestanica, a widely utilized medicinal plant\nin Uzbekistan, has been employed in our research experiments. The extract of\nAjuga turkestanica used in these experiments was supplied by “Bioton”\nLTD, located in Tashkent, Uzbekistan. The chemical agents phenylephrine,\nphentolamine, and verapamil were procured from Sigma-Aldrich Chemie, a division\nof Sigma-Aldrich, based in St. Louis, MO, USA.<\/p>\n\n\n\n

Tissue Preparation<\/strong><\/p>\n\n\n\n

Our institution\u2019s animal use committee authorized\nall experimental procedures andpreoperative care guidelines . The\nanimals were kept in standard vivarium conditions (humidity: 55%\u201365%,\ntemperature: 22\u00b0C \u00b1 2\u00b0C) with free access to drinking water and laboratory\nfood. All manipulations with the animals complied with the European Directive\n2010\/63\/EU on protecting animals used for scientific purposes. The protocol was\napproved by the Animal Ethical Committee based on the Institute of Bioorganic\nChemistry, AS RUz (Protocol Number: 133\/1a\/h, dated August 4, 2014). All\nsurgery was performed under sodium pentobarbital anesthesia, and all efforts\nwere made to minimize suffering6<\/sup>. Experiments were carried out on aortic preparations of\nwhite male rats (weight 200-250 g). The experimental animals were euthanized by\ncervical dislocation, and the chest was opened, the aorta was surgically\nisolated, and it was placed in a special organ bath (5 ml) perfused\nKrebs-Henseleit’s physiological solution (mM): NaCl 120,4; \u041a\u0421l 5; NaHCO3<\/sub> 15,5; NaH2<\/sub>PO4<\/sub>\n1,2; \u041cgCl2<\/sub> 1,2; \u0421a\u0421l2<\/sub> 2,5; \u04216<\/sub>\u041d12<\/sub>\u041e6\n<\/sub>11,5, HEPES \u0440\u041d<\/em> 7.4.\nKrebs solutions without Ca2+<\/sup> were also used for some experiments. For this, EGTA (1 mM) was added to the Krebs\nsolution. Physiological solutions were oxygenated with carbogen (95% O2<\/sub>,\n5% CO2<\/sub>) and maintained at +37\u00b0\u0421 using a DAIHAN WATER BATH ultrathermostat. After\nremoving the connective tissue and fat surrounding the aorta, the aorta was\nsegmented into 3-4 mm rings. <\/p>\n\n\n\n

Aortic-ring\ncontraction studies<\/strong><\/strong><\/p>\n\n\n\n

Aortic rings were mounted to a Radnoti (Isometric-Transducer, USA) sensor using platinum wire hooks. In this condition, the aortic rings were held for 60 min until equilibration. Each preparation was subjected to an initial tension corresponding to 1 g (10 mN). The contraction force is transmitted from the trancducer to a signal amplifier and recorded on a computer using a Go-link automated digital converter. The obtained results were statistically processed using special software packages “OriginLab OriginPro v.8.5 SR1 (EULA, Northampton, MA 01060\u20134401, USA)”. The isometric contraction force (mN) of the rat aortic blood vessel preparation under in vitro conditions was calculated as a percentage (%) in statistical recalculation7<\/sup>. <\/p>\n\n\n\n\n\n
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Figure 1: General manufacturing view of the apparatus for regulating isometric contraction of a rat aortic vascular muscle preparation [Vandier et al., 2002].<\/strong><\/p>\n

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Results and Discussion<\/strong><\/p>\n\n\n\n

It is known that the contraction of the aortic\npreparation induced by KCl (50 mM) is caused by the activation of\npotential-dependent L-type Ca2+<\/sup>-channels located in smooth muscle\ncells8<\/sup>. In this\ncase, due to the increase in the concentration of K+<\/sup> ions in the\nmembrane, the value of the membrane potential changes and the\npotential-dependent L-type Ca2+<\/sup>-channels are activated9<\/sup>. In the conducted experiments, it was observed that\n\u00c1juga turkest\u00e1nica extract significantly relaxes the contraction of aortic\npreparations pre-contracted with KCl (50 mM). In this case, it was found that\n\u00c1juga turkest\u00e1nica extract attenuated aortic contraction induced by KCl (50 mM)\nby 16.8\u00b13.4% and 75.2\u00b13.1% compared to the control at dose-dependent concentrations\n(5-100 \u03bcg\/ml) (Fig. 2).<\/p>\n\n\n\n\n\n
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Figure 2: (Original Recording) The effect of \u00c1juga turkest\u00e1nica extract on contraction of rat aortic smooth muscle preparations induced with KCl (50mM).<\/strong><\/p>\n

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It can be seen that this\nextract has a significant effect on the activity of potential-dependent Ca2+<\/sup>-channels\ninduced by KCl (50 mM).<\/p>\n\n\n\n

In order to verify this\nprediction, experiments were conducted using calcium-free Krebs solution and\npotential-dependent Ca2+<\/sup>-channel blocker – verapamil. It is known\nthat increasing the concentration of KCl in Krebs solution with Ca2+<\/sup>\ndoes not cause contraction in aortic preparations, but adding Ca2+<\/sup>\nions to Krebs solution (0 \u2013 2.5 mM) under these conditions causes contraction\nin aortic preparations10<\/sup>. In our\nexperiments, it was found that \u00c1juga\nturkest\u00e1nica extract (100 \u03bcg\/ml) in Krebs\nsolution and adding Ca2+<\/sup> ions in the presence of 50 mM KCl\nsignificantly reduced the contraction of aortic preparations compared to the\ncontrol (Figure 3).<\/p>\n\n\n\n\n\n
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Figure 3: Effects of [Ca2+<\/sup>] concentration in the medium on the relaxant activity of \u00c1juga turkest\u00e1nica extract.<\/strong><\/p>\n

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Based on the experimental\nresults, the relaxant effect of \u00c1juga turkest\u00e1nica (ajuga)\nextract on aortic contraction induced by KCl is due to the reduction of the\nentry of Ca2+<\/sup> ions through potential-dependent Ca2+<\/sup>\nchannels located in the cell membrane. In our next experiments, in order to\nprove that the relaxant effect of the examined extract depends on L-type Ca2+<\/sup>\nchannels, the interaction with the specific blocker of these channels,\nverapamil, was compared11<\/sup>. For this purpose, the concentration of verapamil 0.1 \u03bcM)\nthat causes a half-maximal contraction of aortic preparations evoked with KCl\n((50 \u03bcM) was used. It was noted\nthat this extract further attenuated aortic contractile activity by 28.1\u00b12.8%\nwhen contraction was evoked in aortic preparations evoked with KCl (50 mM)\nunder these conditions, with an IC50<\/sub> of 41,2 \u03bcg\/ml ajuga extract(EC50<\/sub>)\n(Fig. 4). <\/p>\n\n\n\n\n\n
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Figure 4: Interaction of \u00c1juga turkest\u00e1nica extract and Ca2+-<\/sup>channel
blocker – verapamil (EC50<\/sub>) on contraction of aortic preparations evoked by KCl (50mM) under present conditions.<\/strong><\/p>\n

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Based on the obtained\nexperimental results, the investigated extract has a strong relaxant effect and\nsignificantly reduced the contraction induced by KCl (50 mM). In this case, as\na result of the blocking of potential-dependent L-type Ca2+<\/sup> channels\nlocated in the plasmalemma and the entry of Ca2+<\/sup> ions into them, it\nleads to muscle relaxation. The results of the experiment showed that the\nrelaxant effect of this extract is related to the blocking of L-type Ca2+<\/sup>\nchannels, and these results can be evidenced by the results of the experiment\nconducted with the specific blocker of Ca2+<\/sup> channels, verapamil1<\/sup>2<\/sup>.\n<\/strong><\/p>\n\n\n\n

It is known that in the\ncontractile activity of vascular smooth muscle cells, in addition to\npotential-dependent activated Ca2+<\/sup>L-channels, Ca2+<\/sup>\ntransport systems located in the sarcoplasmic reticulum (SR) are also important1<\/sup>3<\/sup>.\nTherefore, in the next\nexperiments, the effect of ayuga extract on the contraction force induced by the\n\u03b1-adrenoceptor agonist – phenylephrine (1 \u03bcM) under the relaxant effect of the\naortic vascular smooth muscle blocker was studied. It is known that the force\nof contraction caused by phenylephrine (1 \u03bcM) is related to the increase in the\namount of [Ca2+<\/sup>]in at the expense of the Ca2+<\/sup> ions coming\nfrom the SR, and also from the Ca2+<\/sup>-channels controlled by the\nreceptor1<\/sup>4<\/sup>. In experiments with phenylephrine (1\n\u03bcM), it was found that ayuga extract at the maximum concentration (80 \u03bcg\/ml)\nreduced the contraction force induced by phenylephrine (1 \u03bcM) by 66.6\u00b13.3%\ncompared to the control. (Fig. 5).<\/p>\n\n\n\n\n\n
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Figure 5: (Original Recording) The effect of 80 \u03bcg\/ml \u00c1juga turkest\u00e1nica extract on phenylephrine-induced rat aortic contraction.<\/strong><\/p>\n

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Based on the obtained results,\nit can be assumed that the relaxant effect of the studied extract occurs with\nthe blockade of receptor-controlled Ca2+<\/sup>-channels. In order to\nfurther clarify this prediction, the effects of \u03b1-adrenoceptor blocker –\nphentolamine (PE) and flavonoids were compared. <\/p>\n\n\n\n

From the conducted\nexperiments, it was known that in the absence of phentolamine, 1 \u03bcM\nphenylephrine induced reduction of aortic contraction force at the\nconcentration of \u00c1juga turkest\u00e1nica (80 \u03bcg\/ml) as shown in the above\nexperiments. When the effect of phentolamine (10 \u03bcM) on the contraction induced\nby 1 \u03bcM phenylephrine was studied, it was found to decrease the force of\ncontraction by 81.7\u00b13.1% compared to the control. When the effect of \u00c1juga\nturkest\u00e1nica extract was studied in this condition, the contracture in the\npresence of phentolamine was 37.5\u00b14.2%. (Fig. 6).<\/p>\n\n\n\n\n\n
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Figure 6:The effect of phentolamine (10 \u03bcM) on the relaxant effect of \u00c1juga turkest\u00e1nica extract. Effects of \u00c1juga turkest\u00e1nica extract in the presence of phentolamine (10 mkM).<\/strong><\/p>\n

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From the conducted\nexperiments, it was known that the relaxant activity of \u00c1juga turkest\u00e1nica\nextract is related to the blockade of receptor-controlled Ca2+<\/sup>-channels,\nthe results of the experiments conducted with the blocker of \u03b1-adrenoceptors –\nphentolamine (Phe) can be an example.<\/p>\n\n\n\n

The Study the role of endothelium in the relaxant effect of \u00c1juga turkest\u00e1nica extract<\/strong><\/p>\n\n\n\n

It is known from the literature that the endothelial\nlayer plays an important role in the functional activity of blood vessels, that\nis, in maintaining the tone of the vessels. Endothelial cells are located in\nthe inner layer of the blood vessel wall and synthesize locally acting mediators\nthat control blood flow in organs. One of the important active substances of\nisolated endotheliocytes is nitric oxide (NO), an endothelial vasodilator1<\/sup>5<\/sup>. Endothelial\nfunction and structural pathology play an important role in the clinical\nexamination and pathogenesis of arterial hypertension, atherosclerosis. In many\ncardiovascular diseases, endotheliocytes show their initial damage, which\ncauses a cascade of pathological morpho-functional changes and eventually leads\nto extensive dysfunctions1<\/sup>6<\/sup>. These data\nexplain a wide range of functions of endothelial cells: regulation of vascular\ntone, hemostasis, immune system, migration of blood cells along the vascular\nwall, synthesis of inflammatory factors and their inhibitors, and carry out\nbarrier functions1<\/sup>7<\/sup>. Today,\nendothelial dysfunction (ED) is a disturbance in the balance between mediators\nthat ensure the correct direction of all endothelium-related processes. Changes\nin the structure and development of blood vessels associated with vascular\ndiseases, disorders of the ability of blood vessels to respond to external\ninfluences, and disorders in the production of endothelial vasoactive factors\nare observed at the same time1<\/sup>8<\/sup>. The presence of many factors affecting NO metabolism causes endothelial\ndysfunction. Such modifiable risk factors for ED as predictors of\ncardiovascular disease include: hypokinesia, smoking, high salt intake,\npoisonings from various causes, estrogen deficiency, disturbances in\ncarbohydrate, lipid, protein metabolism, infection, etc1<\/sup>9<\/sup>. <\/p>\n\n\n\n

L-arginine amino acid is a substrate for the synthesis of NO in endotheliocytes under the action of NO synthase (eNOS). NO is synthesized as a result of activation of eNOS by calcium-calmodulin and oxidation of L-arginine in a small amount (picomole)20<\/sup>.  Normally, eNOS is bound to caveolin and is associated with caveolae. In this case, the activity of eNOS decreases dramatically. Receptor-dependent stimuli (acetylcholine, bradykinin, serotonin, thrombin, ADF, glutamate, substance R) separate eNOS from the caveolin-eNOS complex and release it from the plasma membrane. As a result of inhibition of excess of one of the main blockers of eNOS activation by forming a heterocomplex with caveolin-1, stimulation of NO formation occurs when statins are used in very low concentrations (0,1 mmol). This is one of the mechanisms of the pleiotropic effects of statins, which serve as a basis for correcting ED21<\/sup>. <\/p>\n\n\n\n

In the development of atherosclerosis and endothelial dysfunction, oxidative stress (OS), in particular, oxygen free radicals, are the main factors in the process of decomposition of local NO, one of the most effective vasodilators. A decrease in the duration of direct action of nitric oxide at the site of formation leads to the development of ED22<\/sup>. Since NO and oxygen radicals chemically neutralize each other, an increase in local oxygen concentration leads to a decrease in biologically active NO23<\/sup>. NO plays a key role here. It is synthesized by NO synthase in endothelial cells of blood vessels. Thus, the activation of the enzyme guanylate cyclase (GTs) through the activity of NO-synthase (eNOS), which is located in the endothelial layer of smooth muscle cells, increases the concentration of cyclic guanylate monophosphate [cGMP], and the activation of protein kinase G (PKG) causes relaxation through the phosphorylation of myosin light chain24<\/sup>. Endothelial cells play an important role in controlling Ca2+<\/sup> homeostasis and the contractile activity of SMCs, and they also modulate the functional state of SMCs and maintain vascular tone by producing a number of vasoactive factors25<\/sup>. The main role is played by nitric oxide (NO), which is synthesized by NO synthase (NOS) in endothelial cells and is the main mediator in vascular smooth muscle relaxation. Diffusion of NO in SMCs activates the NO\/cGC\/cGMP\/PKG signaling pathway, causing a decrease in [Ca2+<\/sup>]i in SMCs and their relaxation, along with activation of IP3R and Ca2+<\/sup>-ATP cells in SR26<\/sup>. Therefore, in order to investigate the involvement of the endothelium in providing the relaxant effect of \u00c1juga turkest\u00e1nica extract, experiments were performed on aorta preparations with the endothelial layer removed. <\/p>\n\n\n\n

In the experiments, a standard method was used to investigate the\npossibility of modulation of the functional activity of the vascular\nendothelial layer under the relaxant effect of the extracts. Aortic smooth\nmuscle preparations were elicited contractions using 1 \u03bcM Phe under conditions\nin which the endothelial layer was removed and the endothelial layer was\npresent. An evoked contraction\namplitude of 10 mN in the aortic preparation under Phe is the standard\ncondition for the experiment. The absence of the endothelial layer of the\naortic preparation is checked using 1 \u03bcM acetylcholine. It was noted that the\namplitude of contraction of the rat aorta vascular preparation in isometric\nconditions caused by the \u03b11-adrenoceptor agonist – 1 \u03bcM phenylephrine was\nreduced by 57.8\u00b14.3% under the influence of 1 \u03bcM acetylcholine. It was found\nthat 1 \u03bcM of acetylcholine has almost no effect on the force of contraction\ninduced by 1 \u03bcM of phenylephrine in the aorta preparation, where the\nendothelial layer was mechanically removed using a cotton swab. <\/p>\n\n\n\n

In the experiments, it was determined that the rat aorta blood vessel\npreparation under the conditions of isometric contraction, under the relaxant\neffect of the extract, changes to the extent that the vascular endothelial\nlayer is removed. It was found that different concentrations (\u03bcg\/ml) of ajuga\nextract reduced the relaxant effect by 57.9\u00b12.8%, respectively, compared to the\ncontrol. It was found that the endothelial layer was reduced by 23.9\u00b13%\ncompared to the existing conditions (Fig. 7).<\/p>\n\n\n\n\n\n
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Figure 7: Relaxant effect of \u00c1juga turkest\u00e1nica extract on the contraction induced by Phe 1 \u03bcM in the presence (+) and denuded (\u2013) of the rat aortic blood vessel endothelial layer.<\/strong><\/p>\n

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As can be seen from the results of the experiment, significant changes\nwere observed when the effect of the examined extract on the aorta preparations\nwith the endothelial layer removed was examined. Based on the obtained results,\nit is possible to estimate the activity of the examined substances on the\nendothelium. In order to further clarify this assumption, experiments were\nconducted in the presence of eNOS blocker-L-NAME (100 \u03bcM). In experiments, in\naortic preparations incubated with L-NAME, it was observed that the relaxant\neffect of \u00c1juga turkest\u00e1nica extract was\nsignificantly attenuated. In the presence of 100 \u03bcM L-NAME, \u00c1juga turkest\u00e1nica extract was\nfound to reduce the contraction force of Phe-induced aortic preparations by\n50.9\u00b12.8%. It was found that the endothelial layer was reduced by 30.9\u00b13%\ncompared to the existing conditions (Fig. 8). <\/p>\n\n\n\n\n\n
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Figure 8: Relaxant effect of \u00c1juga turkest\u00e1nica extract, eNOS blocker \u2013 L\u2013NAME 100 \u03bcM on contraction of rat aortic blood vessel preparation under incubation conditions.<\/strong><\/p>\n

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The results of the series of experiments show that the studied extracts\nhave a strong relaxant effect, which is based on endothelium-dependent\nprocesses. The relaxation effect of the extract is attenuated in the presence\nof endothelium removed and L-NAME, indicating the importance of the role of NO\nsynthase. By activating the NO synthase and cGC\/cGMP\/PKG signaling pathway,\nthey help to reduce the influx of Ca2+<\/sup> ions through the Ca2+<\/sup>L\nand Ca2+<\/sup>R channels in the plasmalemma, and also prevent their\nrelease from the SR, which leads to a decrease in [Ca2+<\/sup>]I in the SMC\nand causes a smooth muscle relaxation. During the next experiments, the effect\nof \u00c1juga turkest\u00e1nica extract on\nthe release of Ca2+<\/sup> ions from SR through IP3<\/sub>R was\ninvestigated. In these experiments, the contraction force induced by\nphenylephrine (1 \u03bcM) in the absence of Ca2+<\/sup> ions in the incubation\nmedium determines the process of Ca2+<\/sup> ion release from SR through IP3<\/sub>R2<\/sup>7<\/sup>. In our\nstudies, the force of contraction caused by phenylephrine (1 \u03bcM) was found to\nbe 69\u00b13.1% compared to the normal Krebs solution, and this contraction was\ntaken as 100%. When we studied the effect of the concentration of \u00c1juga turkest\u00e1nica extract (80\u03bcg\/ml)\nunder these conditions, it was found that it reduced the contraction force by\n40.5\u00b12.8% compared to the control (Figure 9). <\/p>\n\n\n\n\n\n
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Figure 9: Relaxant effect of \u00c1juga turkest\u00e1nica extract on phenylephrine-induced rat aortic contraction in Ca2+<\/sup>-free Krebs solution.<\/strong><\/p>\n

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From the obtained results, it was found that \u00c1juga turkest\u00e1nica extract\nsignificantly reduces the contraction force induced by phenylephrine (1 \u03bcM) in\nthe absence of Ca2+<\/sup> ions. It can be seen that this substance may be\ncaused by its effect on the level of [Ca2+<\/sup>]i, as it inhibits the\nrelease of Ca2+<\/sup> ions from the SR. The obtained results suggest that\nthe relaxant effect of this extract on the contractile activity of the aortic\nblood vessel in Krebs solution without Ca2+<\/sup> ions is mainly related\nto the blockade of Ca2+<\/sup> ions release process from SR through IP3<\/sub>R.\nIn order to confirm this assumption, experiments were carried out using\ncaffeine. According to the literature, under the influence of caffeine, the\nrelease of Ca2+<\/sup> ions from the SR to the cytosol occurs due to the\nactivity of the ryanodine receptor (RyR) located in the SR in smooth muscle\ncells13<\/sup>. In this case, the force of contraction caused by caffeine\nplays an important role as an indicator of the amount of Ca2+<\/sup> ions\nin SR. In the conducted experiments, it was determined that caffeine (10 mM) in\nthe medium of normal Krebs solution containing Ca2+<\/sup> (2.5 mM) causes\na reduction of 62.5\u00b12.2% compared to the effect of phenylephrine (1 \u03bcM). Under\nthese conditions, \u00c1juga\nturkest\u00e1nica extract was found to reduce the contraction force\ninduced by caffeine by 34.5\u00b12.8% compared to the control. (Figure 10). <\/p>\n\n\n\n\n\n
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Figure 10: Relaxant effect of \u00c1juga turkest\u00e1nica extract on caffeine-induced rat aortic contraction in normal Krebs solution.<\/strong><\/p>\n

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The obtained results show that the relaxant effect of this extract on\nthe contraction force induced by caffeine is related to the decrease in the\namount of Ca2+<\/sup> released from the SR. However, the contraction of the\nsmooth muscle cell may be accompanied by Ca2+<\/sup> ions coming from the\nexternal environment through the plasmalemma together with Ca2+<\/sup> ions\ncoming out of the SR under the influence of caffeine2<\/sup>8<\/sup>. Therefore,\nin order to fully clarify the mechanism of action of the extracts on the\ncontraction caused by caffeine, experiments were performed in the absence of Ca2+<\/sup>\nions in the incubation medium. In this condition, it was noted that the\ncontraction force under the influence of caffeine is 35\u00b12.4% compared to the\ncondition in the presence of Ca2+<\/sup> ions. In these conditions,\nexperiments were carried out at concentrations of \u00c1juga turkest\u00e1nica extract (80\n\u03bcg\/ml). As for the contraction force induced by caffeine, when the extract was\nstudied, it was found that the contraction force decreased by 17.9\u00b12.2%\ncompared to the control (Figure 11). <\/p>\n\n\n\n\n\n
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Figure 11: Relaxant effect of \u00c1juga turkest\u00e1nica extract on caffeine-induced rat aortic contraction in Ca2+<\/sup>-free Krebs solution.<\/strong><\/p>\n

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Conclusion<\/strong><\/p>\n\n\n\n

These obtained results show that the studied extracts effectively reduce\npotential dependant Ca2+ <\/sup>L type channels and Phe-induced contraction\nof aortic preparations in Krebs solutions without Ca2+<\/sup> ions, which\nis mainly supported by Ca2+<\/sup> ions released from SR via IP3R. These\ndata suggest that their effect on the release of Ca2+<\/sup> ions from the\nSR via IP3R may play an important role in the relaxant effects of \u00c1juga turkest\u00e1nica extract. In\naddition, when the endothelial layer of the aortic blood vessel was removed,\nthe range of effect was not high, which indicates that the role of the\nendothelium is very important in the regulation of ion channels, so we can\nassume that \u00c1juga turkest\u00e1nica has an effect on smooth muscle ion channels.\nFrom the above, we can conclude that \u00c1juga turkest\u00e1nica has a significant\neffect on potential dependent, receptor dependent, sarcoplasmic reticulum Ca+2<\/sup>\nion channels.<\/p>\n\n\n\n

Acknowledgement<\/strong><\/p>\n\n\n\n

The\nwork was supported by the Applied Research Program of the Ministry of Higher\nEducation, Science and Innovation Republic of Uzbekistan (project A-FA-2021-372\n“Creation of medicine with effective control of the cardiovascular system\nbased on Herba leonuri, Gnaphalii uliginosi herba, Chamomillae recutie\nflores, Crataegi flores<\/em> medicinal plants”)<\/p>\n\n\n\n

Conflict of Interest<\/strong> <\/p>\n\n\n\n

The authors declare that they\nhave no conflict of interest regarding the publication of this article.<\/p>\n\n\n\n

Funding Source<\/strong><\/p>\n\n\n\n

Innovative Development Agency\nunder the Ministry of Higher Education, Science and Innovation, grant number is\nA-FA-2021-372.<\/strong><\/p>\n\n\n\n

References<\/strong><\/p>\n\n\n\n

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