• YAKHAK HOEJI
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• v.32 no.6
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• pp.402-414
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• 1988

In order to clarify the receptor types and mechanisms underlying the positive inotropic effect of dopamine on the mammalian ventricular myocardium, the action potential, its first derivatives and isometric contraction of the rabbit papillary muscle were recorded using a force transducer and glass capillary microelectrodes filled with 3M KCl. The results were as follows; (1) In normal Tyrode solution, the contractile force was increased and duration of action potential was shortened with increments of dopamine concentration ($10^{-6}-10^{-4}M$). (2) The dose-response curve was markedly shifted to the right by pretreatment with reserpine (5mg/kg i.p., 24hrs prior to the experiment). (3) In 19mM $K^+-Tyrode$ solution, the duration of action potential, maximum rate of rise (V_{max}) of action potential and overshoot were significantly increased with increments of dopamine concentration ($10^{-6}-10^{-4}M$). (4) The inotropic effect of dopamine on the rabbit papillary muscle pretreated with reserpine was antagonized by atenolol ($10^{-6}M$), but not by phentolamine ($3{\times}10^{-6}M$). (5) In rabbit papillary muscle partially depolarized by 19mM $K^+-Tyrode$ solution, slow electrical response (calcium mediated action potential) as well as contraction were restored by dopamine ($10^{-4}M$); this restoration was blocked by calcium antagonists ($3{\times}10^{-5}M$ $LaCl_3{\cdot}6H_2O$, $3{\times}10^{-6}M$ diltiazem) or ${\beta}-adrenoceptor$ antagonist ($3{\times}10^{-6}M$ atenolol), but not affected by ${\alpha}-adrenoceptor$ antagonist ($10^{-5}M$ phentolamine, $3{\times}10^{-6}M$ yohimbine) or vascular dopaminergic receptor antagonist ($10^{-5}M$ haloperidol). The above results may be interpreted as that the positive inotropic effect of dopamine through both direct and indirect action are caused by increase in slow inward current ($Ca^{2+}$ influx into themyocardial cell), and the direct action is mainly due to the stimulation of ${\beta}-adrenoceptors$ in the rabbit papillary muscle.

• The Korean Journal of Vision Science
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• v.20 no.4
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• pp.513-521
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• 2018

Purpose : : In this study, we made dopamine-functionalized hydrogels containing a cross-linked hyaluronic acid (HA) network and investigated their antioxidant activities. Methods : In the first step, we made poly hydroxyethyl methacrylate(p(HEMA))-based hydrogels post-modified with an interpenetrating polymer network(IPN) structure composed of HA polymers and a p(HEMA) network. The subsequent functionalization with dopamine via an amide coupling reaction resulted in the antioxidant hydrogels. Their antioxidant activities were evaluated using 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) and 2,2-diphenyl-1-picrylhydrazyl radical scavenging assays. Results : The dopamine-modified hydrogels exhibited significant antioxidant activities, when compared to unmodified control. The presence of the HA-IPN structure improved the surface wettability of the hydrogel while dopamine-conjugated IPN hydrogel did not demonstrate the significant difference compared to hydrogel control. Dopamine-modified hydrogels exhibited high transmittance (>88%). Conclusion : The results demonstrate that the development of antioxidant hydrogels based on dopamine-conjugated HA-IPN structures may help develop ophthalmic and biomedical materials.

• Archives of Pharmacal Research
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• v.20 no.5
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• pp.510-512
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• 1997

The effects of noscapine a phthalide isoquinoline alkaloid, on dopamine biosynthesis and tyrosine hydroxylase (TH) activity in PC12 cells were investigated. Noscapine showed 74.6% inhibition on dopamine content in PC12 cells at a concentration of $20{\mu}M.$ $IC_{50}$ of noscapine was $6.8{\mu}M.$ TH activity was inhibited by the treatment of noscapine in PC12 cells (20.9% inhibition at 20 .mu.M). Therefore, the inhibition of TH activity by noscapine might be involved in at least one component of the reduction of dopamine biosynthesis in PC12 cells.

• BMB Reports
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• v.28 no.4
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• pp.323-330
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• 1995

Recent studies have shown that dopamine applied to cultured swimming motor neurons of Polyorchis penicillatus produces an inhibitory action by opening potassium channels through $D_2$-like receptors. In this study, it was demonstrated that dopamine found in the hydromedusa was not from exogenous sources and the content of dopamine depended on the $Ca^{2+}$ content of the dissecting media. In addition, a combination of thin layer chromatography and high performance liquid chromatography showed the presence of DOPA and DO PAC-like compounds in the jellyfish. The glyoxylic acid method for catecholamines suggested that a population of small cells, neither swimming motor neurons nor B-like neurons, had dopaminergic systems. From all these results, it is suggested here that DA synthesized from DOPA in some cells is released. being dependent on calcium concentrations, into a synaptic cleft and degraded into DOPAC after acting as an inhibitory transmitter to swimming motor neurons.

• BMB Reports
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• v.46 no.11
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• pp.519-526
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• 2013

Dopamine (DA) regulates emotional and motivational behavior through the mesolimbic dopaminergic pathway. Changes in DA signaling in mesolimbic neurotransmission are widely believed to modify reward-related behaviors and are therefore closely associated with drug addiction. Recent evidence now suggests that as with drug addiction, obesity with compulsive eating behaviors involves reward circuitry of the brain, particularly the circuitry involving dopaminergic neural substrates. Increasing amounts of data from human imaging studies, together with genetic analysis, have demonstrated that obese people and drug addicts tend to show altered expression of DA D2 receptors in specific brain areas, and that similar brain areas are activated by food-related and drug-related cues. This review focuses on the functions of the DA system, with specific focus on the physiological interpretation and the role of DA D2 receptor signaling in food addiction.

• Korean Journal of Pharmacognosy
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• v.25 no.2
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• pp.194-197
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• 1994

MeOH extracts of sixteen herbal drugs were tested for the effects on bovine adrenal tyrosine hydroxylase and dopamine ${\beta}-hydroxylase$. The MeOH extracts of Paeoniae Radix and Pinelliae Tuber showed 65% inhibition on the tyrosine hydroxylase activity at the concentration of 100 $\mu$g in the enzyme reaction mixture. Those of Paeoniae Radix, Pinelliae Tuber and Evodiae Fructus showed 87, 84 and 62%, respectively, on the dopamine ${\beta}-hydroxylase$ activity.

• Bulletin of the Korean Chemical Society
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• v.35 no.1
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• pp.25-29
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• 2014

This research was aimed to fabricate an optical fiber-based SERS substrate which can detect dopamine neurotransmitters. Chitosan nanoparticles (NPs) were firstly anchored on the surface of optical fiber, and then gold layer was subsequently deposited on the anchored chitosan NPs via electroless plating method. Finally, chitosan-gold nanocomposites combined with optical fiber reacted with dopamine molecules of 100-1500 mg/day which is a standard daily dose for Parkinson's disease patients. The amplified Raman signal at $1348cm^{-1}$ obtained from optical fiber-based SERS substrate was plotted versus dopamine concentrations (1-10 mM), demonstrating an approximate linearity of Y = 303.03X + 2385.8 ($R^2$ = 0.97) with narrow margin errors. The optical fiber-based Raman system can be potentially applicable to in-vitro (or in-vivo) detection of probe molecules.

• Archives of Pharmacal Research
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• v.17 no.6
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• pp.398-404
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• 1994

The behavioral response, depamine metabolism, and characteristics of dopamine subtypes after developing the hyperlycemia were studied in the striata of rats. In animals developed hyperglycemia, the on-set duration of cataleptic behavior responded to SCH 23390 injection was delayed abd shortened, respectively. However, the cataleptic response to spiperone occurred significantly earlier in on-set and prolonged in duration. Dopamine metabolites, dihydroxyphenylacetic acid (DDPAC) and homovanillic acid (HVA), were significantly reduced in teh striata of hyeprglycemic rats. However, level of DA was significantly increased. It is noted that the ratios of DOPAC and HVA to DA were decreased, suggesting decreased tumover of DA. The affinity of striatal D-1 receptors was significantly increased without changes in the number of binding sites, while the maximum binding number of D-2 recptors was significantly increased without affecting its affinity in the diabetic rats. These results indicate that the dopaminergic activity in striatia was altered in hyperglycemic rats. Furthermore, it suggests that the upregulation of dopamine receptors might be due to the decreased dopamine matabolism.

• YAKHAK HOEJI
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• v.37 no.6
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• pp.561-570
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• 1993

Renal action of domperidone known as dopamine receptor blocker and effect of domperidone on renal function of dopamine were investigated in dog. Domperidone, when administered into vein, produced diuretic action by the improvement of renal hemodynamic state, when given into a renal artery, elicited diuretic action accompanied with natriuresis in only experimental kidney, whereas domperidone given into carotid artery exhibited antidiuretic action by the decrease of Na$^{+}$ excretion in urine. Diuretic action of dopamine was not influenced by domperidone given into vein or into a renal artery, was blocked by domperidone given into carotid artery. Above results suggest that domperidone produced both peripheral diuretic and central antidiuretic action, and domperidone do not block diuretic action by renal hemodynamic improvement of dopamine in kidney.

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.270.1-270.1
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• 2002

The signaling pathway of D2 dopamine receptor was studied using yeaslt two-hybrid system.. The 3rd cytoplasmic loop of rat D2 dopamine receptor was used to screen the cDNA library of mouse brain. and ALY was found to interact with it. The interaction in the yeast was observed only with the 3rd cytoplasmic loop of D2 dopamine receptor but not with that of D3 or D4 dopamine receptor. The interaction between two proteins was also confirmed by GST pull-down assay. (omitted)