• Title/Summary/Keyword: cyclic-GMP

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cyclic GMP Mediated Inhibition of Spontaneous Germinal Vesicle Breakdown Both with and without Cumulus in Mouse Oocyte

  • Hwang, Heekyung;Cheon, Yong-Pil
    • Development and Reproduction
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    • v.20 no.4
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    • pp.359-365
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    • 2016
  • Intact germinal vesicle (GV) arrest and release are essential for maintaining the fertility of mammals inducing human. Intact germinal vesicle release, maturation of oocytes is maintained by very complex procedures along with folliculogenesis and is a critical step for embryonic development. Cyclic guanosine monophosphate (cGMP) has been suggested a key factor for meiotic arrest but so far its mechanisms are controversy. In this study we examine the effects of cGMP on germinal vesicle breakdown in cumulus-enclosed oocytes and denuded oocytes. Spontaneous maturation was inhibited by a cGMP agonist, 8-Br-cGMP with concentration dependent manners both in cumulus-enclosed oocytes and denuded oocytes. The inhibitory effect was more severe in denuded oocytes than cumulus-enclosed oocytes. The Rp-8-Br-cGMP and Rp-pCPT-8-Br-cGMP did not severely block GVB compared to 8-Br-cGMP. The spontaneous GVB inhibitory effects were different by the existence of cumulus. Based on them it is suggested that the cumulus modulates the role of cGMP in GV arrest.

Regulatory Role of Cyclic Nucleotides in Non-Adrenergic Non-Cholinergic Relaxation of Lower Esophageal Sphincter from Dogs (개 하부식도괄약근의 비아드레날린성, 비콜린성 이완반응에 있어서 Cyclic Nucleotide의 역할)

  • Kim Young-Tae;Rhim Byung-Yong
    • The Korean Journal of Physiology and Pharmacology
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    • v.1 no.3
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    • pp.303-313
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    • 1997
  • The role of the lower esophageal sphincter(LES) is characterized by the ability to maintain tone and to relax allowing the passage of a bolus. It is known that LES relaxation during swallowing may be induced by the cessation of the tonic neural excitation and the activation of non-adrenergic, non-cholinergic(NANC) inhibitory neurons. Furthermore, it is generally accepted that the relaxation of the smooth muscle is mediated primarily by the elaboration of adenosine 3',5'-cyclic monophosphate(cyclic AMP) and guanosine 3',5'-cyclic mono-phosphate(cyclic GMP) via activation of adenylate cyclase and guanylate cyclase, respectively. It is thus possible that cyclic nucleotides might be a second messenger involved in neural stimulation-induced relaxation of LES, although a relationship between relaxation and changes in cyclic nucleotides after neural stimulation has not been established. The present study was performed to define the participation of cyclic nucleotides in the relaxation of LES of dog in response to neural stimulation. Electrical field stimulation(EFS) caused relaxation of the canine isolated LES strips in a frequency-dependent manner, which was eliminated by pretreatment with tetrodotoxin$(1{\mu}M)$, but not by atropine$(100{\mu}M)$, guanethidine$(100{\mu}M)$ and indomethacin$(10{\mu}M)$. The nitric oxide synthase inhibitors, $N^G-nitro-L-arginine$, $N^G-nitro-L-arginine$ methyl ester and $N^G-monomethyl-L-arginine$ inhibited EFS-induced relaxation. Additions of sodium nitroprusside, a nitrovasodilator and forskolin, a direct adenylate cyclase stimulant, caused a dose-dependent relaxation of LES smooth muscle. Effects of sodium nitroprusside and forskolin were selectively blocked by the corresponding inhibitors, methylene blue for guanylate cyclase and N-ethylmaleimide(NEM) for adenylate cyclase, respectively. Dibutyryl cyclic AMP and dibutyryl cyclic GMP caused a concentration-dependent relaxation of the LES smooth muscle tone, which was not blocked by NEM or methylene blue, respectively. However, both NEM and methylene blue caused significant antagonism of the relaxation in LES tone in response to EFS. EFS increased the tissue cyclic GMP content by 124%, whereas it did not affect the tissue level of cyclic AMP. Based on these results, it is suggested that one of the components of canine LES smooth muscle relaxation in response to neural stimulation is mediated by an increase of cyclic GMP via the activation of guanylate cyclase. Additionally, an activation of cyclic AMP generation system was, in part, involved in the EFS-induced relaxation.

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Ionic Dependence and Modulatory Factors of the Background Current Activated by Isoprenaline in Rabbit Ventricular Cells

  • Leem, Chae-Hun;Lee, Suk-Ho;So, In-Suk;Ho, Won-Kyung;Earm, Yung-E
    • The Korean Journal of Physiology
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    • v.26 no.1
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    • pp.15-25
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    • 1992
  • In order to elucidate the properties of the background current whole cell patch clamp studies were performed in rabbit ventricular cells. Ramp pulses of ${\pm}80\;mV$ from holding potential of 40 mV(or 20 mV) at the speed of 0.8 V/sec were given every 30 sec(or 10 sec) and current-voltage diagrams(I-V curve) were obtained. For the activation of the background current isoprenaline, adenosine 3',5'-cyclic monophosphate(dBcAMP), guanosine 3',5'-cyclic monophosphate(cGMP), and $N^6$-2'-o-dibutyryladenosine 3',5'-cyclic monophosphate(dBcAMP) were applied after all known current systems were blocked with 2mM Ba, 1 mM Cd ,5 mM Ni, 10 ${\mu}M$ diltiazem, 10 ${\mu}m$ ouabain, and 20 mM tetraethylammonium(TEA). The conductance of background current in control was $0.65{\pm}0.69$ nS at 0 mV, its I-V curves was almost linear and reversed near 50 mV. When there was no taurine in pipette solution, isoprenaline hardly activated the background current but when taurine existed in pipette solution, isoprenaline activated the larger background current. Cyclic AMP or cyclic GMP alone had little effect on the activation of the background current, while cGMP potentiated cGMP effect. When the background current was activated with cGMP and cAMP, isoprenaline could not further increased the background current. The background current activated by isoprenaline depended on extracellular $Cl^-$ concentration and its reversal potential was shifted according to chloride equilibrium potential. The change of extracellular $Na+$ concentration had little effect on reversal potential of the background current activated by isoprenaline.

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Alterations in Cerebrovascular Reactivity by Trigeminovascular System Injury in Rats

  • Park Sang June;Choi Chang Hwa;Lee Won Suk
    • Biomedical Science Letters
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    • v.11 no.2
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    • pp.211-219
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    • 2005
  • Trigeminovascular system plays an important role for the cerebral memodynamics. The aim of this study was to investigate the alterations in cerebrovascular reactivity by trigeminovascular system injury in rats. Trigeminovascular system of male Sprague-Dawley rats was injured by either denervation of nasocilliary nerve or neonatal capsaicin treatment. Trigeminovascular system was stimulated by controlled hemorrhagic hypotension or somatosensory (whisker) stimulation. Changes in regional cerebral blood flow (rCBF) and pial arterial diameter were continuously measured by laser-Doppler flowmetry and videomicroscopy, respectively. Nitric oxide synthase (NOS) activity in cerebral cortex was determined by measuring the conversion of $L-^3H-arginine\;to\;L-^3H-citrulline$. Cyclic GMP levels in cerebral cortex and pial artery were determined using the cyclic GMP $^{125}I$ scintillation proximity assay system. rCBF autoregulation was impaired or almost abolished by trigeminovascular system injury. rCBF response to whisker stimulation was significantly attenuated by trigeminovascular system injury. NOS activity as well as cyclic GMP level in cerebral cortex and pial artery were significantly reduced in the group of trigeminovascular system injury. These results suggest that trigeminovascular system injury causes prominent alterations in cerebrovascular reactivity, and that NO, which is generated by neuronal NOS in the trigeminovascular system, is implicated in the regulation of rCBF.

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Mutant cAMP Receptor Protein Binds to DNA without DNA Bending (DNA 벤딩(휨) 없이 돌연변이 cAMP 수용체 단백질의 결합)

  • Gang, Jong-Back
    • Journal of Life Science
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    • v.16 no.7 s.80
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    • pp.1225-1228
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    • 2006
  • Cyclic AMP receptor protein (CRP) complexed with cAMP binds to DNA and induces sharp DNA bending around ${\sim}90$ degree. Previous publication (5), however, reported that mutant CRP:cGMP complex showed high migration rate relative to mutant CRP:cAMP complex on native polyacrylamide gel. To confirm DNA structural change in the presence of CRP and cyclic nucleotide, molar cyclization factor $(j_M)$ [13] was measured with 6 constructed DNA fragments. Nonlinear regression analysis of $j_M$ data indicated that mutant CRP did not induce DNA bending in the presence of cGMP but bent DNA in the presence of cAMP without any helical twist change in DNA.

Effect of Platelet-Activating Factor on Cyclic Nucleotide Level in Rat Uterine tissue during Preimplantation Period (흰쥐의 임신초기에 있어서 자궁 조직중 Cyclic Nucleotide의 변화 및 Platelet-Activating Factor의 영향에 관한 연구)

  • Park, Kyoung-Sik;Kwun, Jong-Kuk
    • Clinical and Experimental Reproductive Medicine
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    • v.18 no.2
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    • pp.133-142
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    • 1991
  • This study was carried out to observe the change in uterine cyclic nucleotide level and the effect of PAF on cyclic nucleotides in uterine tissue in early pregnany in order to understand reciprocal relation ship between PAF and cyclic nucleotides in pregnancy in the rat. The test groups were injected intramuscularly with $1{\mu}g$ of PAF or 1.25mg of BN-52021 on day 0, 1, 2, 3, 4 and 5 of pregnancy. The level of cyclic nucleotide in removed uterine tissue was assayed by using cyclic nucleotides test kits. The results showed that the cyclic AMP content in uterine tissue of non-pregnant at pro-oestrus rat was $2.91{\pm}0.33$ pmol/mg protein which was lower than those of pregnant rat. The cyclic GMP content in uterine tissue of non-pregnant rat was $0.39{\pm}0.20$ pmol/mg pro-tein which was also lower than those of pregnant rats. The maximum level in cAMP was $5.92{\pm}1.72$ pmol/mg protein on day 3 and cGMP, $1.03{\pm}0.22$ pmol/mg protein on day 4. On each day of pregnancy, PAF induced the increased cAMP level ompared with that of intact rat. That was significant on day 0, 2 and 4 of pregnancy, p<0.05, on the other hand PAF receptor antagonist, BN-52021 ecreased cAMP level in uterine tisssue. PAF as well as BN-52021 had not an consistent effect on changes in cGMP level. These results suggest that cyclic nucleotide levels in uterine tissue ware increased during early pregnancy and PAF influences cAMP level in uterine rather than cGMP level during peri-implantation period, accordingly demonstrating a possible involvement of PAF in the regulation of implantation-related events through cAMP-mediated process.

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Effect of Cyclic GMP on Human Cytomegalovirus Gene Expression (Human Cytomegalovirus 유전자 발현에 Cyclic GMP의 영향)

  • Yoon, Joo-Hyun;Lee, Gyu-Cheol;Song, Byung-Hak;Kim, Young-Jin;Lee, Chan-Hee
    • The Journal of Korean Society of Virology
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    • v.29 no.4
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    • pp.261-269
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    • 1999
  • The relationship between second messenger cGMP and human cytomegalovirus (HCMV) replication was investigated. First, the intracellular level of cGMP ([cGMP]i) in HCMV-infected cells was measured. The [cGMP]i increased at early times after HCMV infection, reached maximum level at 12 hr and returned to basal level at 24 hr after virus infection, while [cGMP]i in mock-infected cells remained relatively unchanged. Increasing [cGMP]i resulted in enhanced transcription of HCMV major immediate early gene. For early gene expression, cGMP had varying effect. Expression of 1.2 kb RNA decreased and 2.2 kb RNA increased with increasing cGMP, while 2.7 kb RNA gene expression was not affected. HCMV early genes are regulated by immediate early gene, and the effect of cGMP on the regulatory effect of major immediate early gene on early genes was investigated. In the absence of cGMP, major immediate early gene repressed 2.7 kb RNA gene expression, while 1.2 kb RNA and 2.2 kb RNA early genes were not significantly affected. In the presence of $1\;{\mu}M$ cGMP, however, major immediate early gene stimulated the expression of three early genes.

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Effects of Hydrochlorothiazide on the Renal Cyclic Nucleotides Level (Hydrochlorothiazide가 신장의 Cyclic Nucleotides 함량에 미치는 영향)

  • Lee, Seok-Yong;Koh, Taek-Lip;Lee, Woo-Young;Lee, Sang-Bok;Cho, Kyu-Chul
    • The Korean Journal of Pharmacology
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    • v.22 no.2
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    • pp.128-134
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    • 1986
  • To determine the relationship between hydrochlorothiazide-induced diuretic action and cyclic nucleotides, the effects of hydrochlorothiazide (5 mg/kg, i.v.) on the renal tissue level of cyclic nucleotides and the renal adenylate cyclase and guanylate cyclase activity were investigated. Hydrochlorothiazide elecitied the maximal diuretic effect between 10 and 20 min after the injection of drug. The increased urine flow and urinary electrolytes excretion returned to the control levels 60 min after the injection of drug. 5 and 15 min after drug administration the cAMP level of renal tissue was significantly decreased, but 60 min after the cAMP level was not different from the control level. The cGMP level of renal tissue was not affected by hydrocholorothiazide. Hydrochlorothiazide $(5\;{\times};10^{-4}\;M)$ inhibited the renal adenylate cyclase but not affected the renal guanylate cyclase. These results suggest that cAMP may be involved in the renal action mechanism of hydrochlorothiazide and the involvement of cGMP is uncertain.

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Effects of Cyclic-GMP on Hyperpolarization-activated inward Current $(I_f)$ in Sino-atrial Node Cells of Rabbit (동방결절에서 과분극에 의해 활성화되는 내향전류에 대한 Cyclic-GMP의 영향)

  • Yoo, Shin;Ho, Won-Kyung;Earm, Yung-E
    • The Korean Journal of Physiology and Pharmacology
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    • v.1 no.6
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    • pp.731-739
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    • 1997
  • The aim of present study is to investigate the effects of cGMP on hyperpolarization activated inward current ($I_f$), pacemaker current of the heart, in rabbit sino-atrial node cells using the whole-cell patch clamp technique. When sodium nitroprusside (SNP, $80{\mu}M$), which is known to activate guanylyl cyclase, was added, $I_f$ amplitude was increased and its activation was accelerated. However, when $I_f$ was prestimulated by isopreterenol (ISO, $1{\mu}M$), SNP reversed the effect of ISO. In the absence of ISO, SNP shifted activation curve rightward. On the contrary in the presence of ISO, SNP shifted activation curve in opposite direction. $8Br-cGMP(100\;{\mu}M)$, more potent PKG activator and worse PDE activator than cGMP, also increased basal $I_f$ but did not reverse stimulatory effect of ISO. It was probable that PKG activation seemed to be involved in SNP-induced basal $I_f$ increase. The fact that SNP inhibited ISO-stimulated $I_f$ suggested cGMP antagonize cAMP action via the activation of PDE. This possibility was supported by experiment using 3-isobutyl-1-methylxanthine (IBMX), non-specific PDE inhibitor. SNP did not affect $I_f$ when $I_f$ was stimulated by $20{\mu}M$ IBMX. Therefore, cGMP reversed the stimulatory effect of cAMP via cAMP breakdown by activating cGMP-stimulated PDE. These results suggest that PKG and PDE are involved in the modulation of $I_f$ by cGMP: PKG may facilitate $I_f$ and cGMP-stimulated PDE can counteract the stimulatory action of cAMP.

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Involvement of Crosstalk Between cAMP and cGMP in Synaptic Plasticity in the Substantia Gelatinosa Neurons

  • Kim, Tae-Hyung;Chung, Ge-Hoon;Park, Seok-Beom;Chey, Won-Young;Jun, Sung-Jun;Kim, Joong-Soo;Oh, Seog-Bae
    • International Journal of Oral Biology
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    • v.36 no.2
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    • pp.83-89
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    • 2011
  • Substantia gelatinosa (SG) neurons receive synaptic inputs from primary afferent $A{\delta}$- and C-fibers, where nociceptive information is integrated and modulated by numerous neurotransmitters or neuromodulators. A number of studies were dedicated to the molecular mechanism underlying the modulation of excitability or synaptic plasticity in SG neurons and revealed that second messengers, such as cAMP and cGMP, play an important role. Recently, cAMP and cGMP were shown to downregulate each other in heart muscle cells. However, involvement of the crosstalk between cAMP and cGMP in neurons is yet to be addressed. Therefore, we investigated whether interaction between cAMP and cGMP modulates synaptic plasticity in SG neurons using slice patchclamp recording from rats. Synaptic activity was measured by excitatory post-synaptic currents (EPSCs) elicited by stimulation onto dorsal root entry zone. Application of 1 mM of 8-bromoadenosine 3,5-cyclic monophosphate (8-Br-cAMP) or 8-bromoguanosine 3,5-cyclic monophosphate (8-Br-cGMP) for 15 minutes increased EPSCs, which were maintained for 30 minutes. However, simultaneous application of 8-BrcAMP and 8-Br-cGMP failed to increase EPSCs, which suggested antagonistic cross-talk between two second messengers. Application of 3-isobutyl-1-methylxanthine (IBMX) that prevents degradation of cAMP and cGMP by blocking phosphodiesterase (PDE) increased EPSCs. Co-application of cAMP/cGMP along with IBMX induced additional increase in EPSCs. These results suggest that second messengers, cAMP and cGMP, might contribute to development of chronic pain through the mutual regulation of the signal transduction.