• The Korean Journal of Physiology and Pharmacology
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• 제2권6호
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• pp.733-742
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• 1998

Background: We have previously reported that not only cGMP but also 8-Br-cGMP or 8-pCPT-cGMP, specific and potent stimulators of cGMP-dependent protein kinase (cGMP-PK), increased basal L-type calcium current $(I_{Ca})$ in rabbit ventricular myocytes. Our findings in rabbit ventricular myocytes were entirely different from the earlier findings in different species, suggesting that the activation of cGMP-PK is involved in the facilitation of $I_{Ca}}$ by cGMP. However, there is no direct evidence that cGMP-PK can stimulate $I_{Ca}}$ in rabbit ventricular myocytes. In this report, we focused on the direct effect of cGMP-PK on $I_{Ca}}$ in rabbit ventricular myocytes. Methods and Results: We isolated single ventricular myocytes of rabbit hearts by using enzymatic dissociation. Regulation of $I_{Ca}}$ by cGMP-PK was investigated in rabbit ventricular myocytes using whole-cell voltage clamp method. $I_{Ca}}$ was elicited by a depolarizing pulse to +10 mV from a holding potential of -40 mV. Extracellular 8-(4-Chlorophenylthio)-guanosine-3',5'-cyclic monophosphate (8-pCPT-cGMP), potent stimulator of cGMP-dependent protein kinase (cGMP-PK), increased basal $I_{Ca}}$. cGMP-PK also increased basal $I_{Ca}}$. The stimulation of basal $I_{Ca}}$ by cGMP-PK required both 8-Br-cGMP in low concentration and intracellular ATP to be present. The stimulation of basal $I_{Ca}}$ by cGMP-PK was blocked by heat inactivation of the cGMP-PK and by bath application of 8-(4-chlorophenylthio)-guanosine-3',5'-cyclic monophosphate, Rp-isomer (Rp-pCPT-cGMP), a phosphodiesterase-resistant cGMP-PK inhibitor. When $I_{Ca}}$ was increased by internal application of cGMP-PK, IBMX resulted in an additional stimulation of $I_{Ca}}$. In the presence of cGMP-PK, already increased $I_{Ca}}$ was potentiated by bath application of isoprenaline or forskolin or intracellular application of cAMP. Conclusions: We present evidence that cGMP-PK stimulated basal $I_{Ca}}$ by a direct phosphorylation of L-type calcium channel or associated regulatory protein in rabbit ventricular myocytes.

• Biomolecules & Therapeutics
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• 제14권2호
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• pp.119-124
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• 2006

This study was performed to investigate the influence of the spinal adenosine $A_1$ receptors on the central regulation of blood pressure (BP) and heart rate (HR), and to define whether its mechanism is mediated by cyclic AMP (cAMP), cyclic GMP (cGMP) or potassium channel. Intrathecal (i.t.) administration of drugs at the thoracic level were performed in anesthetized, artificially ventilated male Sprague-Dawley rats. I.t. injection of adenosine $A_1$ receptor agonist, $N^6$-cyclohexyladenosine (CHA; 1, 5 and 10 nmol) produced dose dependent decrease of BP and HR and it was attenuated by pretreatment of 50 nmol of 8-cyclopentyl-1,3-dimethylxanthine, a specific adenosine $A_1$ receptor antagonist. Pretreatment with a cAMP analogue, 8-bromo-cAMP, also attenuated the depressor and bradycardiac effects of CHA (10 nmol), but not with cGMP analogue, 8-bromo-cGMP. Pretreatment with a ATP-sensitive potassium channel blocker, glipizide (20 nmol) also attenuated the depressor and bradycardiac effects of CHA (10 nmol). These results suggest that adenosine $A_1$ receptor in the spinal cord plays an inhibitory role in the central cardiovascular regulation and that this depressor and bradycardiac actions are mediated by cAMP and potassium channel.

• Archives of Pharmacal Research
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• 제18권6호
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• pp.434-439
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• 1995

In pancreatic cells, NO formation is associated with increased levels of cGMP and endocrine/exocrine secretion. In the present study, the role of NO in the regulation of exocrine secretion was investigated in rat pancreatic tissues. Treatment of rat pancreatic tissue with sholecystokinin-pancreozymin (CCK-PZ) resulted in an significant increase in arginine conversion to citruline, the amount of nitrite/nitrate, the release of amylase, and the level of cGMP. Furthermore, CCK-PZ stimulated increase of amylase release and conversion of arginine to citrulline transformation were counteracted by the inhibitor of NO synthase, $N^G-nitro-L-arginine$ methyl ester. The results on the time course of CCK-PZ-induced citrulline formation within the first seconds of simulation. The kinetics of citrulline accumulation correlate well with those of cGMP rise, which further confirms the conclusion that NO mediates the response to CCK-PZ by cGMP.

• The Korean Journal of Physiology and Pharmacology
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• 제16권3호
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• pp.211-217
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• 2012

Recent studies have demonstrated that nitric oxide (NO) activates transient receptor potential vanilloid subtype 1 (TRPV1) via S-nitrosylation of the channel protein. NO also modulates various cellular functions via activation of the soluble guanylyl cyclase (sGC)/protein kinase G (PKG) pathway and the direct modification of proteins. Thus, in the present study, we investigated whether NO could indirectly modulate the activity of TRPV1 via a cGMP/PKG-dependent pathway in cultured rat dorsal root ganglion (DRG) neurons. NO donors, sodium nitroprusside (SNP) and S-nitro-N-acetylpenicillamine (SNAP), decreased capsaicin-evoked currents ($I_{cap}$). NO scavengers, hemoglobin and 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (CPTIO), prevented the inhibitory effect of SNP on $I_{cap}$. Membrane-permeable cGMP analogs, 8-bromoguanosine 3', 5'-cyclic monophosphate (8bromo-cGMP) and 8-(4chlorophenylthio)-guanosine 3',5'-cyclic monophosphate (8-pCPT-cGMP), and the guanylyl cyclase stimulator YC-1 mimicked the effect of SNP on $I_{cap}$. The PKG inhibitor KT5823 prevented the inhibition of $I_{cap}$ by SNP. These results suggest that NO can downregulate the function of TRPV1 through activation of the cGMP/PKG pathway in peripheral sensory neurons.

• 대한수의학회지
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• 제43권4호
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• pp.615-624
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• 2003

Vascular smooth muscle relaxation is modulated by an increase in cGMP subsequent to nitric oxide (NO) production by endothelial cells. The effects of cAMP and cGMP phosphodiesterase (PDE) inhibitors were investigated in phenylephrine-precontracted rat aorta rings by using the specific inhibitors of PDE I, III, IV and V as relaxing agents (calmodulin-activated PDE inhibitors, IBMX and $W_7$, type I; cAMP-specific PDE inhibitors, milrinone, type IV; Ro 20-1724, type III and cGMP-specific PDE inhibitor, zaprinast, type V). All the PDE inhibitors produced a concentration-dependent relaxation in the ring with intact endothelium (+E). Except for milrinone, all the PDE inhibitors-induced relaxations were inhibited by removal of extracellular $Ca^{2+}$, $N^G$-nitro-L-arginine, $N^G$-nitro-L-arginine methyl ester, methylene blue (MS) or nifedipine. The specific PDE I and PDE IV inhibitors both produced endothelium-independent relaxations which were inhibited by MS in -E rings. However, zaprinast had no effect in -E rings. Except for milrinone, sodium nitroprusside (a NO donor)-induced relaxation was significantly augmented by all PDE inhibitors in +E rings. The results suggest that I) the vasorelaxant properties of IBMX, $W_7$, Ro 20-1724 and zaprinast are dependent on endothelium or on interaction with $Ca^{2+}$ regulation, 2) each PDE is differently distributed in vascular tissues (endothelial and smooth muscle cells), 3) the vasodilations of PDE inhibitors are due to the increase of cAMP and cGMP formation through inhibition of cAMP- and cGMP-PDE and 4) the vasodilation action of milrinone does not involve in endothelial-cyclic nucleotide system.

• Asian-Australasian Journal of Animal Sciences
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• 제17권11호
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• pp.1570-1574
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• 2004

A flock of AA breed chickens were reared in peterstme brood-vait chamber and were provided with high energy pelleted feed. At 14 d of age, a total of 350 birds were randomly divided into 3 groups as follows: 100 birds were exposed to normal ambient temperature of 20$^{\circ}C$ for control group; 150 birds were exposed to lower ambient temperature of 11$^{\circ}C$ to induce ascites (treatment I); and another group of 100 birds were exposed to lower ambient temperature of 11$^{\circ}C$ and fed diet containing 1% L-arginine for ascitic prophylactic treatment (treatment II). Samples were collected from blood and abdominal fluid of chicken at 3, 4, 5, 6 and 7 wk of age subsequently, to analysis the contents of plasma endothelin (ET-1), angiotensin II (Ang II), cyclic adenosine monophosphate (cAMP), cyclic guanosine monophosphate (cGMP). The results indicated that the contents of cAMP, cGMP, and Ang II in reatment I and ascitic broilers were higher than the corresponding control group (p<0.01, p<0.05), ET-1 of preascitic broilers were control group (p<0.05), while there was an insignificant difference with later ascitic broilers. The contents of cAMP and cGMP in treatment II were higher than the treatment I and control groups (p<0.01, p<0.05), whereas, the contents of Ang II were gradually decreased compared to the control group (p<0.05), the contents of ET-1 were insignificantly different. On further analysis, the increased plasma Ang II at low ambient temperature condition in broilers made endothelium cell secretion of increased ET-1, cAMP, cGMP and decreased NO. Therefore, low temperature accelerated ascites syndrome in broilers. Supplemently L-arginine can decrease ET-1, and increase cAMP and cGMP. It is concluded that cAMP mediated in broilers pulmonary hypertension syndrome.

• 대한소아치과학회지
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• 제28권1호
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• pp.72-81
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• 2001

Dendroaspis natriuretic peptide (DNP)는 최근에 green Mamba snake Dendroaspis angusticeps의 독(venom)에서 발견된 17개의 아미노산 disulfide링 구조를 포함하는 38개 아미노산 펩티드로 natriuretic peptide family와 그 구조가 비슷하다. Natriuretic peptide family는 사람과 흰쥐 비만세포로부터 히스타민을 유리시킨다고 알려져 있다. 그러나 DNP가 비만 세포로부터 히스타민을 유리 시키는 여부는 밝혀져 있지 않다. 본 연구는 DNP가 흰쥐 복강 비만세포로부터 히스타민을 유리시키는 여부와 함께 히스타민 유리기전을 구명하고자 실시되었다. 다양한 농도의 DNP를 흰쥐 복강 비만세포에 처리한 다음, 비만세포의 탈과립을 도립 광학현미경으로 관찰하였다. 히스타민 유리량은 방사효소법으로 측정하였고 세포내 칼슘 유입량과 cyclic GMP의 수준은 방사면역법으로 측정하였다. DNP는 흰쥐 복강 비만세포를 탈과립시켰고 농도가 증가함에 따라 비만세포로부터 히스타민 유리량이 증가되었다. 또한 DNP는 농도 증가에 비례하여 비만세포 안으로 세포밖의 칼슘을 유입시켰으며 세포안의 cyclic GMP의 수준을 증가시켰다. 이상의 결과로 미루어, DNP는 비만세포 안의 cyclic GMP와 칼슘의 농도를 증가시켜 비만세포로부터 히스타민을 유리시키는 것으로 생각된다.

• 대한약리학회지
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• 제30권3호
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• pp.343-349
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• 1994

정신병치료제들을 장기투여하여 치료를 시도하였을 때에 생기는 여러 부작용은 그 정도 또한 매우 심각하기 때문에 그들의 치료효과와 함께 야기되는 부작용들을 따로 생각할 수가 없게 되었다. 특히 정신병치료는 그 자체에 대한 병인적 원인을 정확히 알 수 없기에 증상에 따른 대중요법이 일괄적으로 사용되므로, 이러한 현재의 치료방법으로는 부작용들이 더 치명적이 될 수 있기 때문에 일차적으로 이들의 공통적약리작용기전들을 연구하는 것은 매우 필요하다. 최근 NO(Nitric oxide)에 대한 많은 연구들에 의하면, 이들이 중추신경계에서 중요한 second messenger 또는 mediator로 신경활동에 영향을 나타내는 것으로 보고되고 있다. 그러므로 저자들은 먼저 이들 약물들과 NO와의 관계를 연구하고자, 중요한 몇종의 정신병치료제들을 택하여 NO생성에 어떤 영향을 미치는 가를 검색하여 다음과 같은 일차 결과를 얻었다 1. 정신병치료제 수종(chlorpromazine, trifluoperazine promazine, pimozide, clozapine, chlorprothixene, haloperidol)을 택하여 쥐의 소내에서 $[^3H]L-arginine$으로부터 $[^3H]L-citrulline$의 생성양을 측정하여 calmodulin antagonist(calmidazolium)와 비교하였다. 2. 이들을 N1E-115 cell에 투여하여 $[^3H]cyclic$ GMP양을 측정하고 그 결과를 calmida-zolium 과 비교하였다. 3. 이들 약물들은 citrulline과 cyclic GMP 모두의 생성양을 의의있게 억제하였으며 그 기전은 calmidazolium과 매우 유사하였다. 위의 일차적 검색결과에 의하면, 정신병치료약물들의 약리작용 기전중에 일부는 중추신경계내의 NO생성 및 cyclic GMP생성에 영향을 나타내는 것으로 사료되며, 이에는 calcium ion이 상당히 중요한 역할을 하는데, 특히 소뇌에서의 NO생성의 감소는 이들 약물들의 치명적 부작용인 tardive dyskinesia와 매우 깊은 관련을 추측할 수 있다. 그러나, 더 많은 약물들의 검색으로 일관적인 기본 결과가 필요 되고 또 각개 약물의 특정적 기전이 연구되기 위하여 현재 실험중이다.

• Journal of Applied Biological Chemistry
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• 제62권4호
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• pp.425-431
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• 2019

Platelet activation is essential for hemostatic process on blood vessel damage. However, excessive platelet activation can cause some cardiovascular diseases including atherosclerosis, thrombosis, and myocardial infarction. Scoparone is commonly encountered in the roots of genus Artemisia or Scopolia, and has been studied for its potential pharmacological properties including immunosuppression and vasorelaxation, but antiplatelet effects of scoparone have not been reported yet. We investigated the effect of scoparone on human platelet activation prompted by an analogue of thromboxane A₂, U46619. As the results, scoparone dose-dependently increased cyclic adenosine monophosphate (cAMP) levels as well as cyclic guanosine monophosphate (cGMP) levels, both being aggregation-inhibiting molecules. In addition, scoparone strongly phosphorylated inositol 1, 4, 5-triphosphate receptor (IP3R) and vasodilator-stimulated phosphoprotein (VASP), substrates of cAMP dependent kinase and cGMP dependent kinase. Phosphorylation of IP₃R by scoparone resulted in inhibition of Ca²⁺ mobilization in calcium channels in a dense tubular system, and phosphorylation of VASP by scoparone led to an inability of fibrinogen being able to bind to αIIb/β3. Finally, scoparone inhibited thrombin-induced fibrin clotting, thereby reducing thrombus formation. Therefore, we suggest that scoparone has a strong antiplatelet effect and is highly probable to prevent platelet-derived vascular disease.

• Archives of Pharmacal Research
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• 제19권3호
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• pp.201-206
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• 1996

Nitric oxide (NO) is thought to be a second messenger involved in secretion. Upon stimulating pancreatic acinar cells with cholecystokinin-pancreozymin (CCK-PZ), NO formation has been shown to be associated with increased levels of cGMP (Seo et al., 1995). To elucidate the signaling pathway of VIP-induced enzyme secretion, we investigated the NO and cGMP synthesis steps as potential steps where two signal pathways triggered by CCK-PZ and VIP interact. The results obtained in this work provide evidence that increase in pancreatic enzyme secretion by treatment with VIP has no relationship with NOS activity and cGMP level. This conclusion was derived from the following findings that VIP treatment of rat pancreatic tissue increased amylase release as well as protein output in a dose- and time-dependent manner, whereas NOS activity and cGMP synthesis were not affected by VIP treatment as monitored by NOS activity assay and determining cGMP level, which was further confirmed by a NOS-inhibitor study. Consequently, CCK-PZ or VIP increases enzyme secretion in rat pancreatic tissue, but the two hormones are different in their mode of action. Together the results suggest that signaling pathway of VIP-induced enzyme secretion might either bypass the NO and cGMP synthesis steps or lie on a distinct pathway from CCK-PZ-induced pathway.