• Preventive Nutrition and Food Science
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• v.6 no.1
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• pp.43-50
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• 2001

The effects of cardiac ischemia-reperfusion and $\beta$-adrenergic stimulation on metabolic function and energetics were investigated in Lan gendorff-perfused spontaneously hypertensive rat (SHR) hearts. Sarcoplasmic reticulum {TEX}$Ca^{2+}${/TEX}-dependent ATPase and cardiac lactate dehydrogenase (LDH) are additionally studied. The perfusion medium (1.0 mM {TEX}$Ca^{2+}${/TEX}) contained 5 mM glucose(+5 U/L insulin) and 2 mM pyruvate as substrates. Global ischemia was induced by reducing perfusion pressure of 100 to 40 cm {TEX}$H_{2}${/TEX}O, followed by 20 min reperfusin. Isoproterenol (ISO, 1$\mu$M) was infused for 10 min. Coronary vascular resistance and myocardial oxygen consumption ({TEX}$MVO_{2}${/TEX}) of SHR were increased in parallel with enhanced venous lactate during ischemia and reperfusion compared to those of Sprague Dawley (SD) hearts. Although ischemia-induced increase in venous lactate and combined adenosine plus inosine was abolished, coronary vasodilation produced in SD during reperfusion. In SHR, depressed reactive hyperemia was associated with a fall in cardiac ATP and CrP/Pi ratio and a rise in intracellular lactate/Pyruvate ratio. On the other hand, ISO produced coronary functional hyperemia and an increase in {TEX}$MVO_{2}${/TEX}. However, these responses were less than those in SHR hearts. The ATPase activity of SHR was attenuated in free {TEX}$Ca^{2+}${/TEX} concentrations used under basal condition and with ISO compared to that of SD. Venous lactate output and cardiac LDH activity were augmented in SHR as influenced by ISO. These results demonstrate that coronary reactive and functional hyperemia was dpressed in SHR, which cold be explained by alterations in the cytosolic phosphorylation potential and the cytosolic redox state manipulated by LDH, and by abnormal free calcium handling.

• Biomolecules & Therapeutics
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• v.4 no.1
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• pp.97-102
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• 1996

To investigate whether human $\beta$$_2$-adrenergic receptor devoid of the C-terminal two transmembrane helices retain its ligand binding activity and specificity, 5'780-bp DNA fragment of the receptor gene which encodes amino acid 1-260 of human $\beta$$_2$-adrenergic receptor was subcloned into the bacterial fusion protein expression vector and expressed as a form of glutathione-S-transferase (GST) fusion protein in E. coli DH5$\alpha$. The receptor fusion protein was expressed as a membrane bound form which was verified by SDS-PAGE and Western blot. The fusion protein expressed in this study specifically bound $\beta$-adrenergic receptor ligand [$^3$H] Dihydroalprenolol. In saturation ligand binding assay, the $K_{d}$ value was 7.6 nM which was similar to that of intact $\beta$$_2$-adrenergic receptor in normal animal tissue ( $K_{d}$=1~2 nM) and the $B_{max}$ value was 266 fmol/mg membrane protein. In competition binding assay, the order of binding affinity of various adrenergic receptor agonists to the fusion protein was isoproterenol》epinephrine norepinephrine, which was similar to that of intact receptor in normal animal tissue. These results suggest that N-terminal five transmembrane helices of the $\beta$$_2$-adrenergic receptor be sufficient to determine the ligand binding activity and specificity, irrespective of the presence or absence of the C-terminal two transmembrane helices.s.s.s.

• Korean Journal of Veterinary Research
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• v.14 no.1
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• pp.33-40
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• 1974

It has been generally understood that the intestinal tracts are under the control of the autonomic nerves; the parasympathetics are excitatory and the sympathetics inhibitory. However, it is recently reported that the actions of these autonomic nerves in the newborn animals are shown to be different from those in the adult animals in some species. In order to elucidate the role of sympathetic innervation to the intestinal tracts, the effects of periarterial nerve stimulation were studied in the periarterial sympathetics-jejunum preparations of the chick and the effects of some autonomic drugs on the isolated muscle strips were also studied. The results obtained were as follows: 1. The periarterial stimulation in the periarterial sympathetics-jejunum preparation elicited the responses of three patterns; 1) contrcation followed by relaxation 2) contraction only 3) relaxation only. The excitatory response was most effective in the stimulus frequencies of 40 cps, whereas the inhibitory response was maximal in the stimulus frequencies of 30 cycle per second. 2. The excitatory response to the periarterial stimulation was not affected by the pretreatment with phenoxybenzamine, dibenamine, propranolol and atropine, whereas the inhibitory response was completely blocked by the pretreatment with phenoxybenzamine and propranolol. 3. In the periarterial syrnpathetics-jejunum preparation treated with reserpine, the periarterial stimulation evoked only contraction, and the contraction was not affected by the pretreatment with phenoxybenzamine, propranolol and atropine. 4. The administration of norepinephrine evoked a relaxation in the isolated jejunum muscle strips and the effect was completely blocked by the pretreatment with phenoxybenzamine. 5. The administration of isoproterenol produced a relaxation in the isolated jejunum muscle strips and the effect was not affected by pretreatment with phenoxybenzamine, whereas the effect was completely blocked by the pretratment with propranolol. 6) The administration of acetylcholine produced a marked contraction in the isolated jejunum muscle strips and the effect was completely abolished by the pretreatment of atropine. These experimental evidences indicate that the inhibitory response to the periarterial stimulation is due to adrenergic fibers and the excitatory response is due to neither adrenergic nor cholinergic component.

• The Korean Journal of Physiology and Pharmacology
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• v.5 no.6
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• pp.487-494
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• 2001

During depolarization, extrusion of $Ca^{2+}$ from sarcoplasmic reticulum through forward-mode $Na^+-Ca^{2+}$ exchange was studied in the rat ventricular myocytes patch-clamped in whole-cell configuration. In order to confine the $Ca^{2+}$ responses in a micro-domain by limiting the $Ca^{2+}$ diffusion time, rat ventricular myocytes were dialyzed with high (14 mM) EGTA. $K^+$ current was suppressed by substituting KCl with 105 mM CsCl and 20 mM TEA in the pipette filling solution and by omitting KCl in the external Tyrode solution. $Cl^-$ current was suppressed by adding 0.1 mM DIDS in the external Tyrode solution. During stimulation roughly mimicking action potential, the initial outward current was converted into inward current, $47{\pm}1%$ of which was suppressed by 0.1 mM $CdCl_2.$ 10 mM caffeine increased the remaining inward current after $CdCl_2$ in a cAMP-dependent manner. This caffeine-induced inward current was blocked by $1\;{\mu}M$ ryanodine, $10\;{\mu}M$ thapsigargin, 5 mM $NiCl_2,$ or by $Na^+\;and\;Ca^{2+}$ omission, but not by $0.1\;{\mu}M$ isoproterenol. The $I{\sim}V$ relationship of the caffeine-induced current elicited inward current from -45 mV to +3 mV with the peak at -25 mV. Taken together, it is concluded that, during activation of the rat ventricular myocyte, forward-mode $Na^+-Ca^{2+}$ exchange extrudes a fraction of $Ca^{2+}$ released from sarcoplasmic reticulum mainly by voltage-sensitive release mechanism in a micro-domain in the t-tubule, which is functionally separable from global $Ca^{2+}{_i}$ by EGTA.

• Archives of Pharmacal Research
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• v.29 no.11
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• pp.977-983
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• 2006

The objective was to devise an animal model of myocardial infarction (MI) against which cardioprotective drugs might be tested. We describe the effects of nimesulide, a COX experience with development and validation of such a model. The rabbit was chosen in preference to rodents because its heart and cardiac circulation more closely resemble those of human. Thus, the cardiovascular system of anaesthetized male rabbits, 1 to 1.5 kg (n=11), was stressed by a single bolus intravenous injection of isoprenaline (ISP), 65 mg/kg. The effects of the injection were followed for sixteen days and were evaluated in four ways: 1) measurements of creatinine kinase isozyme and troponin-I (TPI) in serum 2) Electrocardiographic (ECG) changes (ST elevation and Q wave development) 3) Cardiac histopathology observed in tissue sections of the isolated of the heart. The histopathological analysis showed that rabbit heart on 2nd day after ISP injection showed changes of coagulation necrosis. Day 4 total coagulation with the loss of nuclear and striation associated with heavy interstitial infiltrate of neutrophils was found. Day 8 after infarction showed collagen deposition with capillary channels in between the remaining islands of myocytes in the infarcted area. On the 16th day scarring was complete. Coronary perfusion rates (CPR) and heart rate (HR) of the infarcted and nimesulide (a COX-2 inhibitor) treated rabbits displayed significant improvement (n=11) on each corresponding day after infarction as compared to the infarcted and saline treated rabbits (P<0.05). All four indices revealed similarities with effects commonly associated with MI in humans.

• The Korean Journal of Physiology and Pharmacology
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• v.25 no.6
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• pp.533-543
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• 2021

Myocardial fibrosis (MF) is the result of persistent and repeated aggravation of myocardial ischemia and hypoxia, leading to the gradual development of heart failure of chronic ischemic heart disease. Triptolide (TPL) is identified to be involved in the treatment for MF. This study aims to explore the mechanism of TPL in the treatment of MF. The MF rat model was established, subcutaneously injected with isoproterenol and treated by subcutaneous injection of TPL. The cardiac function of each group was evaluated, including LVEF, LVFS, LVES, and LVED. The expressions of ANP, BNP, inflammatory related factors (IL-1β, IL-18, TNF-α, MCP-1, VCAM1), NLRP3 inflammasome factors (NLRP3, ASC) and fibrosis related factors (TGF-β1, COL1, and COL3) in rats were dete cted. H&E staining and Masson staining were used to observe myocardial cell inflammation and fibrosis of rats. Western blot was used to detect the p-P65 and t-P65 levels in nucleoprotein of rat myocardial tissues. LVED and LVES of MF group were significantly upregulated, LVEF and LVFS were significantly downregulated, while TPL treatment reversed these trends; TPL treatment downregulated the tissue injury and improved the pathological damage of MF rats. TPL treatment downregulated the levels of inflammatory factors and fibrosis factors, and inhibited the activation of NLRP3 inflammasome. Activation of NLRP3 inflammasome or NF-κB pathway reversed the effect of TPL on MF. Collectively, TPL inhibited the activation of NLRP3 inflammasome by inhibiting NF-κB pathway, and improved MF in MF rats.

• BMB Reports
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• v.54 no.8
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• pp.419-424
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• 2021

Cold-induced norepinephrine activates β3-adrenergic receptors (β3-AR) to stimulate the kinase cascade and cAMP-response element-binding protein, leading to the induction of thermogenic gene expression including uncoupling protein 1 (Ucp1). Here, we showed that stimulation of the β3-AR by its agonists isoproterenol and CL316,243 in adipocytes increased the expression of Ucp1 and Heme Oxygenase 1 (Hmox1), the principal Nrf2 target gene, suggesting the functional interaction of Nrf2 with β3-AR signaling. The activation of Nrf2 by tert-butylhydroquinone and reactive oxygen species (ROS) production by glucose oxidase induced both Ucp1 and Hmox1 expression. The increased expression of Ucp1 and Hmox1 was significantly reduced in the presence of a Nrf2 chemical inhibitor or in Nrf2-deleted (knockout) adipocytes. Furthermore, Nrf2 directly activated the Ucp1 promoter, and this required DNA regions located at -3.7 and -2.0 kb of the transcription start site. The CL316,243-induced Ucp1 expression in adipocytes and oxygen consumption in obese mice were partly compromised in the absence of Nrf2 expression. These data provide additional insight into the role of Nrf2 in β3-AR-mediated Ucp1 expression and energy expenditure, further highlighting the utility of Nrf2-mediated thermogenic stimulation as a therapeutic approach to diet-induced obesity.

• Journal of Physiology & Pathology in Korean Medicine
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• v.38 no.1
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• pp.10-15
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• 2024

Previous studies have highlighted the pivotal role of the β-adrenergic receptor (β-AR) signaling pathway in stimulating cancer metastasis induced by chronic stress. According to the theory of traditional Korean medicine, chronic stress can induce Qi stagnation. Based on the traditional role of premature citrus unshiu peel in moving Qi, we hypothesized that an ethanol extract of premature citrus unshiu peel (EPCU) can attenuate chronic stress-induced cancer progression. In this study, we investigated the potential role of EPCU on modulating the adrenergic agonists-induced metastatic properties of liver cancer cells. Our findings revealed that adrenergic agonists, including norepinephrine (NE), epinephrine (E), and isoproterenol (ISO), augmented the migratory capacity of Hep3B human hepatocellular carcinoma cells, which was completely abrogated by EPCU treatment in a concentration-dependent manner. Consistently, EPCU inhibited the E-induced invasive property of Hep3B cells in a dose-dependent manner. These results suggest that EPCU efficiently attenuates adrenergic agonists-induced metastatic abilities of liver cancer cells. As a molecular mechanism, EPF suppressed the phosphorylation of major components of β-AR signaling pathway, including Src, signal transducer and activator of transcription 3 (STAT3) and ERK, induced by E treatment. Taken together, our results demonstrate that EPCU impedes the adrenergic agonists-driven metastatic potential of cancer cells by inhibiting β-AR signaling pathway. This study provides basic evidence supporting the probable use of premature citrus unshiu peel to prevent metastasis in liver cancer patients under chronic stress.

• The Korean Journal of Pharmacology
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• v.22 no.1 s.38
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• pp.24-33
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• 1986

To ascertain the existence of various adrenoceptors involved in active transport of sodium in the frog skin and to delineate their physiological roles, the influence of various adrenergic agonists and antagonists on the potential difference (PD), short-circuit current (SCC) and total skin conductance (TSC) of the isolated frog skin of Rana nigromaculata were investigated. PD and SCC were determined with Ussing's technique. Drugs were administered to the serosal side of the skin. Experimental results were summarized as follows: 1. The responses to norepinephrine (NE, $6{\times}10^{-8}-6{\times}10^{-5})M$), phenylephrine (PE, $5{\times}10^{-6}-5{\times}10^{-4}M$) and epinephrine (Epi, $5.5{\times}10^{-7}-5.5{\times}10^{-5}M$) were characterized by marked elevation of PD & SCC in dose-related fashion, but the maximal effect attained by Epi was less than those of NE and PE. 2. These increments of PD & SCC were significantly inhibited by prazosin $(2{\times}10^{-6}M)$, a speciflc ${\alpha}_1$-adrenoceptor blocker. The stimulatory effect on PD & SCC were completely abolished by phenoxybenzamine (PBZ, $3.3{\times}10^{-5}M$), an irreversible ${\alpha}$-adrenoceptor blocking agent. Furthermore, with a larger doses of Epi produced marked decline of PD & SCC after the PBZ pretreatment. 3. Isoproterenol (ISP), a ${\beta}$-adrenoceptor agonist, in concentrations ranging from $5{\times}10^{-7}$ to $5{\times}10^{-6}M$ produced dose-related decrease in PD & SCC, which could be abolished by pretreatment with propranolol $(4{\times}10^{-6}M)$, a specific ${\beta}$-adrenoceptor blocker. It was further noted that the effects of Epi on PD & SCC were markedly potentiated by Propranolol pretreatment. 4. Clonidine as well as guanabenz produced increases in PD & SCC and these effects were inhibited more specifically by prazosin pretreatment than by yohimbine. These results indicated that there exist in the frog skin two distinctive types of adrenoceptors, ${\alpha}$ and ${\beta}$, which roughly corresponds to those in mammals, and that the ${\alpha}$ type of adrenoceptors mediate the stimulation of PD & SCC, whereas ${\beta}$-adrenoceptors mediate the inhibition. However, based on evidence at hand, no conclusion could be drawn on the subtype of ${\alpha}$-adrenoceptors which is involved in the stimulation of sodium transport in the frog skin.

• The Korean Journal of Pharmacology
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• v.14 no.1_2
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• pp.33-40
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• 1978

1) The authors studied the effect of increasing age on the contraction and relaxation mechanism in the ureteral smooth muscle of the guinea pig. 2) Two to three week old, three month old, and two to three year old guinea pig ureters were used and the consistent amplitude of contratile responses were induced by using train stimulation. 3) After mounting the specimens in Tyrode's solution containing 2.6mM $Ca^{++}$, the ureter was stimulated, of which amplitude was initial contraction and next continuously superfused with $Ca^{++}$-free Tyrod's solution. When the contractile response stopped by electrical field stimulation, the muscle specimens was superfused with Tyrode's solution 0.25mM $Ca^{++}$ for 15min and stimulated with the same parameters. Thereafter, the contraction of $Ca^{++}$ in the solution was increased step by step up to 2.7mM. 4) The ureters of 2-3 week old guinea pigs needed less $Ca^{++}$ for the recovery of contractile response than those of three month and two to three year old did. In 2.7mM $Ca^{++}$, the ureters of 2-3 week and 3 month old guinea pigs recovered the contractile response of over 90% but those of 2-3 year old recovered the contractility of 77.2%. 5) Isoproterenol inhibited in dose dependent manner from $10^{-7}$ to $10^{-5}\;M$ ureteral contractility of both 2-3 week and 2-3 year old guinea pigs. The inhibition of the old ureter by isoproterenol was significantly less (P<0.025) than that of the younger ureter. However theophylline showed the strong inhibition independent of the function of age. 6) Dibutyryl cyclic AMP showed dose-dependent inhibition of the contraction of ureters of 2-3 week old guinea pigs but there was shown no inhibition in the old ureters. Further, the content of endogenous cyclic AMP in the two week old ureter was higher by 73% than that of 17 month old ureter. Cyclic GMP contents was not much different between two groups. 7) The ureteral smooth muscle of the younger guinea pig had more efficiency than that of the older animals in the mobilization and storage of calcium which concerned itself in the contraction and relaxation mechanism.