• Molecules and Cells
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• v.21 no.3
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• pp.337-342
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• 2006

Interstitial cells of Cajal (ICCs) are pacemaker cells that activate the periodic spontaneous depolarization (pacemaker potentials) responsible for the production of slow waves in gastrointestinal smooth muscle. The effects of vasoactive intestinal polypeptide (VIP) on the pacemaker potentials in cultured ICCs from murine small intestine were investigated by whole-cell patch-clamp techniques. Addition of VIP (50 nM-$1{\mu}M$) decreased the amplitude of pacemaker potentials and depolarized resting membrane potentials. To examine the type of receptors involved in ICC, we examined the effects of the $VIP_1$ agonist and found that it had no effect on pacemaker potentials. Pretreatment with $VIP_1$ antagonist ($1{\mu}M$) for 10 min also did not block the VIP (50 nM)-induced effects. On the other hand exposure to 1H-(1,2,4)oxadiazolo(4,3-A)quinoxalin-1-one (ODQ, $100{\mu}M$), an inhibitor of guanylate cyclase, prevented VIP inhibition of pacemaker potentials. Similarly KT-5823 ($1{\mu}M$) or RP-8-CPT-cGMPS ($10{\mu}M$), inhibitors of protein kinase G (PKG) blocked the effect of VIP (50 nM) on pacemaker potentials as did N-nitro-L-arginine (L-NA, $100{\mu}M$), a non-selective nitric oxide synthase (NOS) inhibitor. These results imply that the inhibition of pacemaker activity by VIP depends on the NO-cGMP-PKG pathway.

• Korean Journal of Veterinary Research
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• v.34 no.1
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• pp.135-139
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• 1994

In the year 1992/93 leucocytozoonosis could be first diagnbosed in 87 chickens of 4 chicken farms in Honam districts. The diagnosis was confirmed by detection of the blood merozoites or gametocytes and histological finding of the schizonts from various organs with some clinical signs. Cases of leucocytozoonosis only occurred from the end of June to the middle of September. Artificial infection could be observed by means of inoculation of infected blood merozoites. The schizonts were found in the liver and cardiac muscle of the different chickens recovered from the natural infection, respectively, in September and next February. Thus the relapse or long-term infection in cold seasons might be possible. The unique gametocyte antigen polypeptide was 50.1 kD.

• The Korean Journal of Physiology and Pharmacology
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• v.2 no.4
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• pp.443-454
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• 1998

The present study was attempted to investigate the effect of vasoactive intestinal polypeptide (VIP) on secretion of catecholamines (CA) and to establish whether there is the existence of a noncholinergic mechanism in adrenomedullary CA secretion from the isolated perfused rat adrenal gland. The perfusion into an adrenal vein of VIP $(3{\times}10^{-6}\;M)$ for 5 min or the injection of acetylcholine (ACh, $5.32{\times}10^{-3}\;M$) resulted in great increases in CA secretion. Tachyphylaxis to releasing effect of CA evoked by VIP was not observed by the repeated perfusion. The net increase in adrenal CA secretion evoked by VIP still remained unaffected in the presence of atropine or chlorisondamine. However, the CA release in response to ACh was greatly inhibited by the pretreatment with atropine or chlorisondamine. The releasing effects of CA evoked by either VIP or ACh were depressed by pretreatment with nicardipine, TMB-8, and the perfusion of $Ca^{2+}$-free medium. Moreover, VIP- as well as ACh-evoked CA secretory responses were markedly inhibited under the presence of $(Lys^1,\;Pro^{2.5},\;Arg^{3.4},\;Tyr^6)-VIP$ or naloxone. CA secretory responses induced by ACh and high $K^+\;(5.6{\times}10^{-2}\;M)$ were potentiated by infusion of VIP $(3{\times}10^{-6}M\;for\;5\;min)$. Taken together, these experimental results indicate that VIP causes CA release in a fashion of calcium ion -dependence, suggesting strongly that there exists a noncholinergic mechanism that may be involved in the regulation of adrenomedullary CA secretion through VIP receptors in the rat adrenal gland, and that VIP may be the noncholinergic excitatory secretagogue present in the chromaffin cells.

• Journal of Life Science
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• v.21 no.3
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• pp.473-479
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• 2011

Adenylyl cyclase (AC) catalyzes the formation of cyclic AMP (cAMP) from ATP. The cAMP produced by AC serves as a secondary messenger in a variety of signal transduction pathways, and controls various cellular functions in many organisms. ACs can be grouped into six classes based on their primary amino acid sequences. Eukaryotes and mycobacteria contain only members of class III AC. The catalytic cyclase domains of class III AC are active as dimers: mammalian ACs, which are composed of a single polypeptide with two catalytic cyclase domains, form the active site as a result of intramolecular dimerization of the catalytic cyclase domains. In contrast, mycobacterial ACs function as homodimers, since their polypeptides contain a single catalytic cyclase domain. Six amino acids are required for the catalytic activity of class III AC - two aspartate residues, a lysine-aspartate pair and an arginine-asparagine pair. 16 ACs belonging to the class III were identified in Mycobacterium tuberculosis H37Rv, and their characteristics are reviewed.

• Mass Spectrometry Letters
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• v.12 no.4
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• pp.179-185
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• 2021

Collision-induced dissociation (CID) combined with electrospray ionization mass spectrometry (ESI-MS) was used to obtain structural information on rat islet amyloid polypeptide (rIAPP) monomers (M) and dimers (D) observed in the multiply charged state in the MS spectrum. MS/MS analysis indicated that the rIAPP monomers adopt distinct structures depending on the molecular ion charge state. Peptide bond dissociation between L₂₇ and P₂₈ was observed in the MS/MS spectra of rIAPP monomers, regardless of the monomer molecular ion charge state. MS/MS analysis of the dimers indicated that D⁵⁺ comprised M²⁺ and M³⁺ subunits, and that the peptide bond dissociation process between the L₂₇ and P₂₈ residues of the monomer subunit was also maintained. The observation of (M+ b₂₇)⁴⁺ and (M+ y₁₀)³⁺ fragment ions were deduced to originate from the two different D⁵⁺ complex geometries, the N-terminal and C-terminal interaction geometries, respectively. The fragmentation pattern of the [M_rIAPP + M_hIAPP]⁵⁺ MS/MS spectrum showed that the interaction occurred between the two N-terminal regions of M_rIAPP and M_hIAPP in the heterogeneous dimer (hetero-dimer) D⁵⁺ structure.

• The Korean Journal of Pharmacology
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• v.28 no.2
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• pp.147-162
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• 1992

The objectives of the present experiments were to characterize the effects of the peptides belonging to the pancreatic polypeptide family on the contractility of cerebral arteries and to observe the interactions of these peptides with the cyclic nucleotide activators and the potassium channel openers. Dogs of either sex, $20{\sim}30\;Kg$ in weight, were sacrificed. Basilar and middle cerebral arteries from brain were isolated and prepared for myography in the PSS equilibrated with 95% $O_2$ and 5% $CO_2$ at $37^{\circ}C$. The endothelial cells of the spiral strips were removed by CHAPS solution (0.3% w/v, 15 seconds). 1. PP, PYY and NPY contracted the arterial strips concentration-dependently with a rank order of potency of PYY>NPY>PP. These peptides were 20 to 200 times more potent than norepinephrine, and only PYY showed a greater potency than 5-HT. 2. Cyclic nucleotide activators, forskolin (for cAMP) and sodium nitroprusside (for cGMP) reduced the basal tone and inhibited the PP-, PYY- and NPY- induced contractions by concentration-dependent manners. Forskolin was more potent in reducing basal tone than sodium nitroprusside. 3. Potassium channel openers, RP 49356, P 1060 and BRL 38227 reduced the basal tone concentration-dependently and tended to inhibit the PP-, PYY- and NPY- induced contractions. Notably, BRL 38227 with low concentration $(0.1\;{\mu}M)$ enhanced the contractions induced by those peptides while P 1060 inhibited the contractions concentration-dependently. 4. The combinations of the cyclic nucleotide activators and the potassium channel openers were slightly additive in reducing the basal tone. P 1060 and BRL 38227 enhanced the relaxant effect of sodium nitroprusside significantly. On the PYY-induced contration $(0.1\;{\mu}M)$, $K^+$ channel openers tended to inhibit the inhibitory actions of forskolin and sodium nitroprusside. P 1060 and BRL 38227 antagonized the inhibitory action of sodium nitroprusside significantly. The results of the present study may be summarized that in canine cerebral arteries, not only NPY but also PYY may play a role in a cerebrovascular spasm, and intracellular concentration of either cAMP or cGMP may be involved in the mechanism of vasoconstrictive actions of these peptides, which may be affected either positively or negatively by a $K^+$ channel opener.

• Journal of Ginseng Research
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• v.13 no.2
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• pp.158-164
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• 1989

In order to determine the relationships between the lea(-burning disease and the light harvesting chlorophyll-protein (LHCP) complex in Panax ginseng C. A. Meyer, we investigated the chlorophyll-protein (CP) complex of the thylakoid membrane and its characteristics. In P. ginseng four Cp-complex bands determined by non-denaturing SDS-PAGE were identified CP I'(containing reaction center of photosystem I and LHCP I antennae), CP I (reaction center of photosystem I) LHCP II** (oligoform of LHCP II), and LHCP II (photosystem II antennae, CP 26 and CP 29) by Bassis and Dunahay's procedures. Under our experimental condition, the CP I band was only observed in P. ginseng and the band intensity of LHCP II** in P ginseng was higher than in spinach and soybean. There were differences in the absorption and fluorescence spectra and chlorophyll a/b ratio of the CP-complex bands between P. ginseng and other Plants. The Polypeptidr content of P. ginseng thylakoid was lower than in spinach and soybean thylakoid, and the Polypeptide profiles of P. ginseng was low band intensity, especially about 29-35 kD, 55 kD, and 60 kD, compared to spinach and soybean. The inhibitory effects of 2,5-dimethylfuran, specific singlet oxygen ($^1O_2$) quencher, showed that singlet oxygen destroyed 60% of chl.a, 90% of chl.b and 70% of carotenoid in bleaching P. ginseng with leaf-burning disease.

• Korean Journal of Weed Science
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• v.12 no.4
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• pp.368-373
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• 1992

The effect of alachlor treatment on protein synthesis was studied. Protein synthesis was inhibited by $1{\times}10^{-4}$ M and $1{\times}10^{-3}$M of alachlor 5.8% and 86.5%, respectively, while did not occur blow $1{\times}10^{-5}$M alachlor. Soluble protein of alachlor treated oat root tips was examined by polyacrylamide gel electrophoresis. The proteins extracted from oat root tips showed that they were made up of subunits blow 100 kd polypeptides by SDS-PAGE. As compared to control, high molecular proteins(above 47 kd) were inhibited of oat root treated with alachlor, while low molecular proteins(below 23 kd) were increased. Two-D gels showed that alachlor caused decrease(1-6 spots) or increase(7-10 spots) in number of polypeptides on silver staining. The intensity of some polypeptides of soluble proteins (molecular mass of 83 kd : 1, 2 spots, 70 kd : 3, 4 spots, and 47.5 kd : 5, 6 spots) decreased in alachlor treatment, whereas the intensity of other peptide bands (20 kd : 7 spot and 16 kd : 8, 9, 10 spots) increased. Oat root tip proteins present in the neutral zone are masked by diffusing of major proteins, but proteins in acid zone are resolved minor proteins.

• Development and Reproduction
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• v.2 no.1
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• pp.21-27
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• 1998

The present study was performed to analyze the gene expressions of pituitary adenylate cyclase-activating polypeptide(PACAP) and its receptor in the rat uterus, a candidate for novel extrahypothalamic source and target. The PACAP cDNA fragments corresponding to the common exon region which is found in both the rat hypothalamus and testis were produced from all tissue samples including the rat uterus by reverse transcriptionpolymerase chain reaction (RT-PCR). No PCR product was amplified from the rat hypothalamic, pituitary, ovarian and uterine samples when the 5' primer corresponding to the testis-specific exon 1 region was used, while the predicted size of product was detected from the testis sample. RT-PCR using the uterine RNA and specific primers for the PACAP receptor yielded products with predicted sizes. Transcripts for the rat uterine PACAP receptor were identified as type I isoforms with hip-hop and hip- or hop-type inserts. After pregnant mare's serum gonadotropin (15 IU) treatment of immature rats (day 25), the level of PACAP mRNA was increased in 24 h and 48 h group, and was declined to the lowest in 72 h group. The present study shows the presence of transcripts for PACAP and its receptor isoform in the rat uterus. These finding ssuggest that the uterine PACAP ight act as a novel autocrine and/or paracrine factor via its specific receptors on the reglulation of rat uterine function and physiology during the reproductive cycle.

• Korean Journal of Veterinary Research
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• v.35 no.3
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• pp.447-458
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• 1995

This study was carried out to characterize nonadrenergic, noncholinergic(NANC) relaxation of porcine retractor penis(PRP) muscle induced by electrical field stimulation(EFS) and to investigate the actions of niric oxide(NO) and vasoactive intestinal polypeptide(VIP) as candidates for NANC neurotransmitters. Biphasic relaxations of PRP muscle were induced by EFS to NANC nerve. Rapid-phase relaxation was observed at low frequency(0.5-16Hz) and slow-phase relaxation followed during high frequency(8-60Hz). Both relaxations were frequency-dependent and TTX($1{\times}10^{-6}M$)-sensitive. L-NAME($2{\times}10^{-5}M$) inhibited the rapid-phase relaxation, but not the slow-phase relaxation. The inhibition of the rapid-phase relaxation with L-NAME was reversed by L-arginine ($1{\times}10^{-3}M$) but not by D-arginine($1{\times}10^{-3}M$). Methylene blue($4{\times}10^{-5}M$) reduced the rapid-phase relaxation. Exogenous No(ExoNO, $1{\times}10^{-5}-1{\times}10^{-4}M$) induced dose-dependent relaxations of PRP muscle. Oxyhemoglobin($5{\times}1^{-5}M$) blocked the relaxation induced by ExoNO and inhibited EFS-induced relaxation. Hydroquinone($1{\times}10^{-4}M$) also abolished the relaxation induced by ExoNO, but did not affect EFS-induced relaxation. L-NAME resistant slow-phase relaxation to EFS was inhibited by ${\alpha}$-chymotrypsin(2.5 U/ml). Both methylene blue($4{\times}10^{-5}M$) and Nethylmaleimide($1{\times}10^{-4}M$) reduced the slow-phase relaxation by EFS. [4-Cl-D-$Phe^6$, $Leu^{17}$]-VIP($3{\times}10^{-6}M$) inhibited the slow-phase relaxation by EFS. External applications of VIP ($1{\times}10^{-7}M$) caused relaxations that were simillar to the L-NAME resistant slow-phase relaxations induced by EFS, and relaxant effects of exogenous VIP were blocked by ${\alpha}$-chymotrypsin(2.5 U/ml).