• The Korean Journal of Physiology and Pharmacology
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• 제8권1호
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• pp.43-50
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• 2004

Ischemia followed by reperfusion in the presence of polymorphonuclear leukocytes (PMNs) results in a marked cardiac contractile dysfunction. Amrinone, a specific inhibitor of phosphodiesterase 3, has an antioxidant activity against PMNs. Therefore, we hypothesized that amrinone could attenuate PMNs-Induced cardiac dysfunction by suppression of reactive oxygen species (ROS) produced fby PMNs. In the present study, we examined the effects of amrinone on isolated ischemic (20 min) and reperfused (45 min) rat hearts perfused with PMNs. Amrinone at $25\;{\mu}M$, given to hearts during the first 5 min of reperfusion, significantly improved coronary flow, left ventricular developed pressure (P<0.001), and the maximal rate of development of left ventricular developed pressure (P<0.001), compared with ischemic/reperfused hearts perfused with PMNs in the absence of amrinone. In addition, amrinone significantly reduced myeloperoxidase activity by 50.8%, indicating decreased PMNs infiltration (p< 0.001). Superoxide radical and hydrogen peroxide production were also significantly reduced in fMLP- and PMA-stimulated PMNs pretreated with amrinone. Hydroxyl radical was scavenged by amrinone. fMLP-induced elevation of $[Ca^{2+}]_i$ was also inhibited by amrinone. These results provide evidence that amrinone can significantly attenuate PMN-induced cardiac contractile dysfunction in the ischemic/reperfused rat heart via attenuation of PMNs infiltration into the myocardium and suppression of ROS release by PMNs.

• 약학회지
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• 제36권3호
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• pp.259-268
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• 1992

A procedure for the determination of KR-30075 and its metabolites in plasma and urine by high performance liquid chromatography is described. For the study of pharmacokinetic properties of KR-30075, a new PDE III inhibitor, the plasma concentration and urinary excretion after an oral administration of KR-30075 (4 mg/kg) in the male rat (Sprague Dawley) were determined by high performance liquid chromatography. The best extraction efficiency of KR-30075 and KR-30072 is obtained with ethyl ether adjusted to pH 4.0. Retention times of both KR-30072 and KR-30075 were within 5 min and resolution was complete at the flow rate of 1.0 ml/min. The sensitivity and specificity of this HPLC assay appears to be satisfactory for the pharmacokinetic study of KR-30075 and its metabolites. One-compartment open model with first-order absorption was applied to evaluate the pharmacokinetic parameters of KR-30075 according to Minimum AIC Estimation. $T_{max}$ was 1 hr, $C_{max}$ was $0.789{\pm}0.31\;{\mu}g/ml$ and elimination half $T_{1/2}$ was 6.31 min after oral administration of 4 mg/kg KR-30075 to male rats.

• The Korean Journal of Physiology and Pharmacology
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• 제5권2호
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• pp.139-146
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• 2001

L-type $Ca^{2+}$ channels play an important role in regulating cytosolic $Ca^{2+}$ and thereby regulating hormone secretions in neuroendocrine cells. Since hormone secretions are also regulated by various kinds of protein kinases, we investigated the role of some kinase activators and inhibitors in the regulation of the L-type $Ca^{2+}$ channel currents in rat pituitary $GH_3$ cells using the patch-clamp technique. Phorbol 12,13-dibutyrate (PDBu), a protein kinase C (PKC) activator, and vanadate, a protein tyrosine phosphatase (PTP) inhibitor, increased the $Ba^{2+}$ current through the L-type $Ca^{2+}$ channels. In contrast, bisindolylmaleimide I (BIM I), a PKC inhibitor, and genistein, a protein tyrosine kinase (PTK) inhibitor, suppressed the $Ba^{2+}$ currents. Forskolin, an adenylate cyclase activator, and isobutyl methylxanthine (IBMX), a non-specific phosphodiesterase inhibitor, reduced $Ba^{2+}$ currents. The above results show that the L-type $Ca^{2+}$ channels are activated by PKC and PTK, and inhibited by elevation of cyclic nucleotides such as cAMP. From these results, it is suggested that the regulation of hormone secretion by various kinase activity in $GH_3$ cells may be attributable, at least in part, to their effect on L-type $Ca^{2+}$ channels.

• 한국동물학회지
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• 제30권1호
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• pp.1-9
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• 1987

생쥐 난자-난구 복합체를 인공배양하면서 adenylate cyclase의 촉진제인 forskilin과 phosphodiesterase의 저해제인 3-isobutyl-1-methylxanthine(IBMX)을 배양액에 첨가하여 이들이 난구세포의 분산과 난자의 성숙(핵붕괴)에 미치는 효과를 관찰한 결과 다음과 같았다. 1. Forskilin은 0.001$\mu$M에서 부터 난구세포의 분산을 유도하기 시작하여 (36%) 0.1-10$\mu$M 구간에서 최대의 분산율을 나타내었고 (80-90%) 100$\mu$M에서는 그 효과가 줄어들었다(60%). 이때 난자의 핵 붕괴는 10$\mu$M까지 정상으로 일어나다 (75-80%) 100$\mu$M에서 부분적으로 억제되기 시작하였다(40%). 2. IMBX는 0.01$\mu$M에서 부터 난구세포의 분산을 유도하기 시작하여 (30%) 1-1,000$\mu$M의 전 구간에서 최대의 분산율(81-89%)을 나타내었다. 난자들은 10$\mu$M의 농도까지 정상적으로 핵 붕괴를 일으키었으나(90% 이상) 100$\mu$M 이상에서 급격히 억제되었다(14%). 3. 난구세포의 분산을 유도하는데 필요한 최소의 자극기간을 조사해 본 결과 HCG는 2분, FSH와 forskilin은 15-30분, IBMX는 2시간이었다. 위 결과로 부터 생쥐 난구세포에서 cAMP의 농도를 높이는데 adenylate cyclase 와 phosphodiesterase의 두 효소가 모두 중요한 기여를 하며 난구세포는 단 기간에 생긴 cAMP의 peak로서 분산이 유도될 수 있으나 난자의 성숙억제 과정에서는 지속적인 cAMP의 존재가 필요하다는 것을 알았다.

• Journal of Korean Neurosurgical Society
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• 제65권5호
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• pp.665-679
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• 2022

Objective : Patients with mild ischemic stroke experience various sequela and residual symptoms, such as anxious behavior and deficits in movement. Few approaches have been proved to be effective and safe therapeutic approaches for patients with mild ischemic stroke by acute stroke. Sildenafil (SIL), a phosphodiesterase-5 inhibitor (PDE5i), is a known remedy for neurodegenerative disorders and vascular dementia through its angiogenesis and neurogenesis effects. In this study, we investigated the efficacy of PDE5i in the emotional and behavioral abnormalities in rats with mild ischemic stroke. Methods : We divided the rats into four groups as follows (n=20, respectively) : group 1, naïve; group 2, middle cerebral artery occlusion (MCAo30); group 3, MCAo30+SIL-pre; and group 4, MCAo30+SIL-post. In the case of drug administration groups, single dose of PDE5i (sildenafil citrate, 20 mg/kg) was given at 30-minute before and after reperfusion of MCAo in rats. After surgery, we investigated and confirmed the therapeutic effect of sildenafil on histology, immunofluorescence, behavioral assays and neural oscillations. Results : Sildenafil alleviated a neuronal loss and reduced the infarction volume. And results of behavior task and immunofluorescence shown possibility that anti-inflammation process and improve motor deficits sildenafil treatment after mild ischemic stroke. Furthermore, sildenafil treatment attenuated the alteration of theta-frequency rhythm in the CA1 region of the hippocampus, a known neural oscillatory marker for anxiety disorder in rodents, induced by mild ischemic stroke. Conclusion : PDE5i as effective therapeutic agents for anxiety and movement disorders and provide robust preclinical evidence to support the development and use of PDE5i for the treatment of mild ischemic stroke residual disorders.

• 생명과학회지
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• 제26권12호
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• pp.1367-1375
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• 2016

Cilostazol은 phosphodiesterase III의 선택적 저해제로 알려져 있으며, 뇌졸중 치료에 일반적으로 사용되고 있다. Cilostazol을 처리한 경우, 국소 뇌허혈이 발생한 후에 혈관신생을 통해서 혈관형성이 향상된다는 것을 본 연구자들이 발표하였다. 혈관신생은 조직의 허혈상태를 극복하기 위해서 혈관재생을 촉진하는 중요한 과정으로써, 혈관내피세포의 증식, 이동, 모세관구조 형성의 다단계 과정으로 구성되어 있다. 이에 본 연구에서는 인간 뇌혈관내피세포를 이용하여 cilostazol이 혈관신생의 각 단계들에 어떤 영향을 미치는지 조사하였다. Cilostazol은 농도의존적으로 뇌혈관내피세포의 이동성을 촉진하였으나, 뇌혈관내피세포의 증식과 모세관구조 형성에는 영향을 미치지 않았다. Cilostazol이 세포이동을 조절하는 기전을 분석하기 위해서 cDNA microarray를 수행하였고, 세포이동에 관련성이 있는 5종의 후보 유전자들을 선택하여 real-time PCR을 통해 해당 유전자의 발현을 검증하였다. Cilostazol에 의해서 발현양이 조절되는 유전자들로써, phosphoserine aminotransferase 1 (PSAT1)와 CCAAT/enhancer binding protein ${\beta}$ ($C/EBP{\beta}$)은 발현이 증가하였고, tissue factor pathway inhibitor 2 (TFPI2), retinoic acid receptor responder 1 (RARRES1), RARRES3는 발현이 감소하였다. 이상의 결과를 통해서 cilostazol이 혈관내피세포의 이동을 촉진하여 혈관신생을 향상시킬 수 있음을 제안할 수 있으며, 뇌혈관내피세포에 대한 cilostazol의 조절기전에 대해서 더욱 상세히 규명을 한다면 혈관형성을 통하여 허혈성 질환을 치료할 수 있는 유용한 정보가 될 것으로 기대한다.

• 한국임상수의학회지
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• 제21권3호
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• pp.291-297
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• 2004

Aminoglycosidic antibiotics have multiple effects on muscle. For example, they have been shown to block L-type $Ca^{2+}$ channels in vascular smooth muscle, cardiac muscle and skeletal muscle. Possibly as a consequence of this effect on $Ca^{2+}$ influx, they have been shown to decrease the contractility of cardiac muscle (gentamicin). The present study evaluated the effects of gentamicin on blood pressure, vasorelaxation and left ventricular pressure. Gentamicin(10, 20, 40mg/kg) produced dose-dependent blood pressure lowering in rat. The pretreatment of MgSO$_4$ and imipramine (Na$^{+}$-Mg$^{2+}$ exchange inhibitor) had no effect in gentamicin-induced hypotension. However, the gentamicin-induced hypotension was significantly potentiated in the preincubation of verapamil or nifedipine (L-type $Ca^{2+}$ channel blockers), and was significantly attenuated by CaCl$_2$ and was slightly attenuated by caffeine (phosphodiesterase inhibitor). Gentamicin (10, 30, 100$\mu$g/m1) did not have an effect on relaxation of phenylephrine-precontracted aortic rings but high concentration of gentamicin(100, 300$\mu$g/ml) relaxed KCl-precontracted aortic rings, which relaxation was potentiated by treatment of nifedipine. Whereas gentamicin markedly decreased left ventricular developed pressure (LVDP) in perfused heart. These data suggest that gentamicin has significant blood pressure lowering of the rat, which seems to be mediated by calcium channel-sensitive pathway and blood $Ca^{2+}$ level may be important role in this response.

• The Korean Journal of Physiology and Pharmacology
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• 제3권3호
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• pp.275-282
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• 1999

Muscle strips and muscle cells from cat stomach were used to investigate whether spontaneously formed cyclic nucleotides were involved in the inhibition of gastric smooth muscle contraction. A phosphodiesterase inhibitor, 3-isobutyl-1-methylxanthine (IBMX), increased the levels of both cyclic GMP (cGMP) and cyclic AMP (cAMP) in resting state cells, while decreasing acetylcholine-induced muscle contraction. Under the influence of IBMX, SQ22536, an adenylyl cyclase inhibitor and methylene blue, a guanylyl cyclase inhibitor completely blocked increases in cAMP and cGMP respectively, without any effect on contraction. However, the combination of SQ22536 and methylene blue completely blocked increases in both cAMP and cGMP levels and stimulated contractions markedly even in the presence of IBMX. Muscle contraction inhibitors such as isoprenaline, vasoactive intestinal polypeptide and sodium nitroprusside also appeared to increase cyclic nucleotide levels which decreased contraction. Which nucleotide increased the most was dependent on the agonist used. Therefore, irrespective of the cyclic nucleotide class, the spontaneous formation of cyclic nucleotides should be considered in evaluating the mechanism of gastric smooth muscle relaxation.

• The Korean Journal of Physiology and Pharmacology
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• 제10권3호
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• pp.149-154
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• 2006

Selective inhibition of phosphodiesterase (PDE) 5 opened a new therapeutic approach for cardiovascular disorders. Therefore, the effect of PDE5 inhibition on the cardiac function should thoroughly be defined. The purpose of the present study was to define the effects of sildenafil, a selective inhibitor of PDE5, on the atrial cGMP efflux, atrial dynamics, and the release of atrial natriuretic peptide (ANP). By perfusing rabbit left atria to allow atrial pacing, changes in atrial stroke volume and pulse pressure, transmural extracellular fluid translocation, cGMP efflux, and ANP secretion were measured. SIN-I, an NO donor and soluble (s) guanylyl cyclase (GC) activator, and C-type natriuretic peptide (CNP), an activator of particulate (p) GC activator, were used. Sildenafil increased basal levels of cGMP efflux slightly but not significantly. Sildenafil in a therapeutic dose increased atrial dynamics (for atrial stroke volume, $2.84{\pm}1.71%$, n=12, vs $-0.71{\pm}0.86%$, n=21; p<0.05) and decreased ANP release ($-9.02{\pm}3.36%$, n=14, vs $1.35{\pm}3.25%$, n=23; p < 0.05), however, it had no effect on the SIN-1- or CNP-induced increase of cGMP levels. Furthermore, sildenafil in a therapeutic dose accentuated SIN-1-induced, but not CNP-induced, decrease of atrial pulse pressure and ANP release. These data indicate that PDE5 inhibition with sildenafil has a minor effect on cGMP levels, but has a distinct effect on pGC-cGMP- and sGC-cGMP-induced contractile and secretory function.

• 대한수의학회지
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• 제44권3호
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• pp.357-366
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• 2004

We studied the effect of propofol (PPF) on the endothelium-dependent vascular responses in isolated rat thoracic aorta. In aortic rings with endothelium, PPF inhibited the phenylephrine (PE)-induced contraction in a concentration-dependent manner. In PE-precontracted preparations, PPF attenuated the endothelium-dependent relaxation by acetylcholine but not by A23187. And PPF did not attenuate the endothelium-independent relaxation by sodium nitroprusside (SNP). The relaxation induced by acetylcholine in PE-precontracted aortic rings was significantly augmented by zaprinast, a cGMP-specific phosphodiesterase inhibitor, and this augmentation was inhibited by PPF. Although SNP-induced relaxation was significantly augmented by zaprinast, this augmentation was not inhibited by PPF. In preparations preconstricted with PE, the PPF-induced relaxation was inhibited by atropine. In addition, PPF attenuated the vasorelaxation by phosphodiesterase inhibitors (IBMX, Ro20-1724 or zaprinast except milrinone). In vivo, the infusion of acetylcholine and SNP showed decreased arterial blood pressure in rats. The pre-injection of PPF inhibited the acetylcholine-induced blood pressure lowering, but not the SNP-induced blood pressure lowering. These results suggest that PPF can attenuate in part the acetylcholine-induced vasorelaxation and blood pressure lowering through the inhibition of the acetylcholine receptor-mediated endothelium-derived relaxing factor by acting on endothelium. It is considered that the inhibitory effect of PPF on the vasorelaxation is due to the decreased level of cGMP which can be attributed to the inhibition of the muscarinic receptor and/or receptor-G-protein interaction.