• The Korean Journal of Pharmacology
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• v.21 no.2
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• pp.79-89
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• 1985

Mechanism of calcium transport inhibition of cardiac sarcoplasmic reticulum (SR) by oxygen free radicals was examined. Effects of oxygen free radicals generated by xanthine/xanthine oxidase (X/XO) system on isolated porcine ventricle SR were studied with respect to its calcium binding, lipid peroxidation, SH-group content and alteration of membrane protein components. The results are as follows. 1) Calcium binding of isolated SR was markedly inhibited by X/XO. 2) During the incubation of sarcoplasmic reticulum with xanthine/xanthine oxidase, there were marked inclose in lipid peroxidation and reduction of SH-group content. 3) An antioxidant, p-phenylenediamine effectively prevented the lipid peroxidation but partially prevented the calcium binding inhibition of X/XO treated SR. 4) The reduction of SH-group content of SR treated with X/XO was partially prevented by p-phenylendiamine. 5) When modifying SH-group of SR by treatment with DTNB, the inhibition of calcium binding activity was partially prevented. 6) On gel-permeation chromatography of X/XO-treated sarcoplasmic reticulum, there was an increase of small molecular weight products, probably protein degradation products. 7) Semicarbazide, which prevents the cross-linking reaction of protein components, did not affect the calcium binding inhibition of X/XO-treated SR. From these results, it is suggested that the inhibition of calcium binding of SR by oxygen free radicals results from the consequence of multiple changes of SR components, which are lipid peroxidation, SH-group oxidation and degradation of protein components.

• Journal of Chest Surgery
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• v.19 no.2
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• pp.197-208
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• 1986

Propranolol is one of clinically useful antiarrhythmic agents and electrophysiologically classified as group II. And the negative inotropic effect which is not related to adrenolytic effect has been demonstrated with high concentration of propranolol. On the other hand, it has been well known that the calcium plays a central role in excitation-contraction coupling process of myocardium and also in electrophysiological changes of cell membrane. Author studies the effect of propranolol on calcium uptake and release in sarcoplasmic reticulum and mitochondria prepared from porcine myocardium to investigate the mechanism of action of propranolol on myocardium. The results are summarized as follow: 1] The maximum Ca++-uptake of sarcoplasmic reticulum is inhibited by propranolol in a dose dependent manner. 2] The release of calcium from sarcoplasmic reticulum is not affected by propranolol but with higher than 1x10-3 M of propranolol, rate of calcium release from sarcoplasmic reticulum is decreased. 3] Propranolol inhibits the maximum uptake and uptake rate of calcium in mitochondria non-competitively. [Ki = 6.21 x 10-4 M] 4] The rate of Na+ induced calcium release from mitochondrion shows a function of [Na+]2 and is inhibited by propranolol with the concentration significantly lower than that affect the calcium uptake in sarcoplasmic reticulum and in mitochondria [Ki = 2.91 x 10-5 M]. These results suggest that propranolol affects the intracellular calcium homeostasis which may considered to be one of the mechanism of action of propranolol on myocardium.

• The Korean Journal of Zoology
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• v.19 no.4
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• pp.161-170
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• 1976

Since caffeine inhibits the active uptake of Ca by the sarcoplasmic reticulum, the action of caffeine on the fragmented sarcoplasmic reticulum of rabbit skeletal muscle was studied. Caffeine seemed not to bind tightly to the sarcoplasmic reticulum. The determination of sulfhydryl content of the fragmented sarcoplasmic reticulum, however, suggested that caffeine in some unknown manner influences the protein moiety and thereby increases the sulfhydryl content. The inhibition of Ca uptake by caffeine therefore might be considered as due to the result of this change in protein sulfhydryl content.

• The Korean Journal of Physiology
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• v.20 no.2
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• pp.157-164
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• 1986

Since it has been reported that vanadate inhibits $Ca^{++}-ATPase$ activity without affecting $Ca^{++}$ uptake, this study was undertaken to investigate the effects of vanadate on $Ca^{++}-ATPase$ activity and $Ca^{++}$ uptake in the sarcoplasmic reticulum of rat skeletal muscle. The following results were obtained. 1) $Ca^{++}$ activated ATPase activity of the intact sarcoplasmic reticulum was significantly inhibited when vanadate was added to the incubation medium at concentration greater than $10^{-6}\;M$. However $Mg^{++}$-ATPase activity of the intact SR was not affected by vanadate at concentrations ranging from $10^{-7}\;to\;10^{-4}\;M.$ Similarly, $Ca^{++}-ATPase$ activity in sonicated sarcoplasmic reticulum was significantly reduced by vanadate at a concentration $10^{-7}$ M or higher. 2) The uptake of $Ca^{++}$ by isolated sarcoplasmic reticulum was also inhibited by vanadate under the conditions where the turnover rate of $Ca^{++}-ATPase$ was made to increase. These results suggest that the inhibition of $Ca^{++}$ uptake by vanadate may be correlated with that of $Ca^{++}-ATPase$ if experimental conditions are properly set.

• Korean Journal of Pharmacognosy
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• v.15 no.1
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• pp.24-29
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• 1984

It was previously reported from our laboratory that the rate of deterioration of contractile force was slower in the heart of the ginseng extract treated rats. It was also found that ginseng may have an ability to sustain the normal function of the heart by sustaining Ca accumulation by sarcoplasmic reticulum. $Ca^{++}-dependent$ ATPase plays the central role in movement of $Ca^{++}$ ion from sarcoplasm into sarcoplasmic reticulum. In this investigation, the fragment of sarcoplasmic reticulum was prepared from rat heart treated with ginseng water extract orally 100mg/kg/day for 7 to 10 days and from normal rat heart. $Ca^{++}-dependent$ APTase activity was estimated by a modified method of Fiske and Subbarow's procedure. Experimental groups were divided into 6 groups, depending on the preincubation time, 5, 30 and 60min. at ${25}^{\circ}C$ and ${37}^{\circ}C$ respectively. In both of the groups of ${25}^{\circ}C$ and ${37}^{\circ}C$, $Ca^{++}-dependent$ ATPase activities of the ginseng treated rat hearts were higher than that of normal hearts. Therefore, it can be concluded that $Ca^{++}-dependent$ ATPase activities in sarcoplasmic reticulum of rat hearts were increased by the treatment with ginseng extract.

• The Korean Journal of Zoology
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• v.33 no.2
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• pp.191-199
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• 1990

Sarcoplasmic reticulum subfractions were isolated from rabbit sarcoplasmic reticulum vesicles using ultracentrifugation in a continuous sucrose gradient (12.5% 50%) after French pressure treatment. And proteins in sarcoplasmic reticulum were detected by SDS-polyacrylamide gel electrophoresis and glycoproteins were identified through the reaction with 1251-concanavalin A.The electrophoresis showed that sarcoplasmic reticulum contained predominantly $Ca^2$+-AThase and calsequestrin along with high affinity calcium binding protein, intrinsic glycoprotein 160 Kd, 94 Kd, 80 Kd, 38 Kd, 34 Kd and 24 Kd proteins. Among these, the protein of about 80 Kd which has been known as one of heat shock proteins was especially enriched in the terminal cistemae of sarcoplasmic reticulum. Meanwhile, autoradiogram of 125 I-concanavalin A bound to the stained gels showed the distribution of glycoproteins which included 160 Kd glycoprotein, 94 Kd glycoprotein, calsequestrin and intrinsic glycoprotein Among these, the protein of about 160 Kd was especially enriched in longitudial sarcoplasmic reticulum and T-tubule, and the protein of about 94 Kd which has been known as one of glucose-regulated proteins was also enriched in T-tubule and sharply reduced in terminal cistemae.

• Korean Journal of Food Science and Technology
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• v.21 no.2
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• pp.173-179
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• 1989

The influence of the storage temperature and time after slaughter on the thermal denaturation of PSE porcine muscle protein was studied by differential scanning calorimetry and by measuring the solubility of the sarcoplasmic proteins. In the DSC therodiagram a decrease of the endotherm enthalpy of the myosin plus sarcoplasmic proteins in PSE muscle could be observed with an increase in the storage temperature and time of post mortem. Storage temperature at $20^{\circ}C$ during the first four hours of post mortem resulted in relatively slight denaturation of myosin plus sarcoplasmic proteins in PSE muscle. Storage temperature above $25^{\circ}C$ caused to increase the denaturation of muscle proteins. The minimal drip loss in PSE muscle could be observed, when the muscle was cooled to $2^{\circ}C$ as quickly as possible post mortem. However, when stored for several hours of post morte at a temperature between $32^{\circ}C-38^{\circ}C$, the drip loss reached the level established for PSE muscle. The paleness of PSE muscle could be prevented to some extent by rapid chill to $20^{\circ}C$ post mortem. The more the muscle proteins in the PSE muscle become denatured during the early storage period of post mortem, the more the drip loss increases. With the increase in the denaturation of myosin plus sarcoplasmic proteins in PSE muscle with regard to temperature of post mortem, there was a corresponding decrease in the solubility of the sarcoplasmic proteins in PSE muscle.

• BMB Reports
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• v.43 no.3
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• pp.151-157
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• 2010

$Ca^{2+}$ is a universal signalling molecule that affects a variety of cellular processes including cardiac development. The majority of intracellular $Ca^{2+}$ is stored in the endoplasmic and sarcoplasmic reticulum of muscle and non-muscle cells. Calreticulin is a well studied $Ca^{2+}$-buffering protein in the endoplasmic reticulum, and calreticulin deficiency is embryonic lethal due to impaired cardiac development. Despite calsequestrin being the most abundant $Ca^{2+}$-buffering protein in the sarcoplasmic reticulum, viability is maintained in embryos without calsequestrin and normal $Ca^{2+}$ release and contractile function is observed. The $Ca^{2+}$ homeostasis regulated by the endoplasmic and sarcoplasmic reticulum is critical for the development and proper function of the heart.

• Animal Bioscience
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• v.35 no.1
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• pp.96-104
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• 2022

Objective: Sarcoplasmic proteins include proteins that play critical roles in biological processes of living organisms. How seasons influence biological processes and meat quality of postmortem muscles through the regulation of protein phosphorylation remain to be investigated. In this study, the phosphorylation of sarcoplasmic proteins in pork longissimus muscle was investigated in four seasons. Methods: Sarcoplasmic proteins were extracted from 40 pork carcasses (10 for each season) and analyzed through ProQ Diamond staining for phosphorylation labeling and Sypro Ruby staining for total protein labeling. The pH of muscle, contents of glycogen and ATP were measured at 45 min, 3 h, and 9 h postmortem and the water (P_2b, P₂₁, and P₂₂) was measured at 3 h and 9 h. Results: A total of 21 bands were detected. Band 8 (heat shock cognate 71 kDa protein; heat shock 70 kDa protein 1B) had higher phosphorylation level in summer than that in other seasons at 45 min postmortem. The phosphorylation levels of 3 Bands were significantly different between fast and normal pH decline groups (p<0.05). The phosphorylation levels of 4 bands showed negative associations with immobilized water (P₂₁) and positive association with free water (P₂₂). Conclusion: The phosphorylation levels of sarcoplasmic proteins involved in energy metabolism and heat stress response at early postmortem time differed depending on the seasons. These proteins include heat shock protein 70, pyruvate kinase, phosphoglucomutase-1, glucose-6-phosphate isomerase, and carbonic anhydrase 3. High temperatures in summer might result in the phosphorylation of those proteins, leading to pH decline and low water holding capacity.

• The Korean Journal of Pharmacology
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• v.18 no.2
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• pp.79-87
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• 1982

Higenamine(dl-demethylcoclaurine, dl-1-(4-hydroxybenzyl)-6,7-dihydroxy-1,2,3,4-tetrah-ydroisoquinoline hydrochloride), which has recently been isolated from Aconite root by Drs. Kosuge and Yokota, has known to be the main cardiotonic component of the Aconite root. The present study was undertaken to investigate the effects of Higenamine on the calcium binding and release and ATPase activity of fragmented cardiac sarcoplasmic reticulum under in vitro condition. The calcium binding and release of sarcoplasmic reticulum were measured by using the double-beam spectrophotometer and the calcium sensitive dye, murexide. In the presence of $10^{-4}{\sim}5{\times}10^{-3}M$ of Higenamine, the maximal calcium binding and the initial binding rate of porcine cardiac sarcoplasmic reticulum were inhibited dose dependently by up to 43%. However, the calcium release from cardiac sarcoplasmic reticulum, which was loaded with $Ca^{++}(50{\mu}M)$, was stimulated in dose dependent manner. When incubated in the medium of 20 mM Tris-maleate(pH 7.0), 100 mM KCl, 10 mM $MgCl_2,\;0.05mM\;CaCl_2\;and\;0.014{\sim}1\;mM\;Tris-ATP\;at\;30^{\circ}C$ in the presence of Higenamine $(10^{-4}{\sim}5{\times}10^{-3}M)$, both $Ca^{++}-and\;Mg^{++}-ATPase$ of sarcoplasmic reticulum were inhibited non-competitively by Higenamine and values of $K_i$ were 4.896 mM and 6.875 mM respectively. It is suggested from the above findings that the cardiotonic effects of Higenamine might be partially explained by the inhibition of calcium binding and the stimulation of calcium release from the sarcoplasimic reticulum which may increase the free intracellular calcium that is available in the contraction of the cardiac muscle fiber.