• Korean Journal of Veterinary Research
• /
• v.43 no.3
• /
• pp.405-414
• /
• 2003

The purpose of this study was to assess the role of tachykinins (TK) in mediating nonadrenergic noncholinergic (NANC) contractions produced by electrical field stimulation (EFS) in the longitudinal muscle of the rat ileum. In the presence of atropine ($1{\mu}M$), guanethidine ($5{\mu}M$), and L-nitroarginine (L-NNA, $200{\mu}M$), EFS (0.5ms pulse duration, 120 V, 1-20 Hz for 2 min) produced a frequency-dependent slowly-developing tonic contraction with superimposed phasic contractions ('on'-contraction) followed by off slowly-decreasing tonic and superimposed phasic contractions ('off'-contraction) of mucosa-free longitudinal oriented muscle strip. These EFS induced responses were blocked by tetrotoxin. $NK_1$ receptor selective antagonist L-732,138 strongly inhibited the EFS-induced excitatory responses. However $NK_2$ receptor selective antagonist, GR 159897 and $NK_3$ receptor selective antagonist SB 222200 did not significantly inhibited the responses. $NK_1$ receptor selective agonist [$Sar^9$,$Met(O_2)^{11}$] Substance P and $NK_2$ receptor selective agonist [${\beta}-Ala^8$]-neurokinin A (4-10) induced tonic contraction with superimposed phasic contractions of longitudinal oriented muscle strip and almost blocked by selective antagonist L-732,138 and GR 159897, respectively. But $NK_3$ receptor selective agonist senktide did not showed any effect. Nifedipine ($1{\mu}M$) abolished the contraction produced either by EFS or by the TK receptor agonists [$Sar^9$,$Met(O_2)^{11}$] Substance P or [${\beta}-Ala^8$]-neurokinin A (4-10). It is concluded that, in the longitudinal muscle of rat ileum, both $NK_1$ and $NK_2$ receptors modulated the responses to exogenous tachykinins, whereas $NK_1$ is mainly involved in NANC neuromuscular contraction.

• The Korean Journal of Physiology and Pharmacology
• /
• v.4 no.5
• /
• pp.369-378
• /
• 2000

This study was undertaken to investigate an involvement of nitroxergic innervation in gastric smooth muscle of rat. Isometric tension study, the measurement of single cell length, NADPH diaphorase stain of smooth muscle layers and neuronal nitric oxide synthase (nNOS) western blotting were performed. Sodium nitroprusside (SNP), a nitric oxide donor, relaxed the muscle strips precontracted by acetylcholine (ACh) in a concentration-dependent manner. Pretreatment of L-arginine decreased the contraction induced by electric field stimulation (EFS). Pretreatment of $N^G-nitro-L-arginine$ methyl ester (L-NAME), a NOS inhibitor, increased the EFS-induced contractions. LY 83583, a guanylate cyclase (GC) inhibitor, reversed the inhibitory actions of L-arginine on the muscle contractions. The effects of L-Arginine, L-NAME and LY 83583 on ACh-induced contractions were not significant. L-arginine reduced the EFS-induced contraction in circular muscle, whereas L-NAME enhanced the EFS-induced contraction in longitudinal strips. By EFS, the phasic contractions appeared approximately $20{\sim}25$ seconds later. L-NAME significantly shortened the delay time to about $2{\sim}3$ seconds. In single cell study, ACh contracted gastric smooth muscle cells, SNP relaxed the cells, and the latter also inhibited the ACh-induced contraction. LY 83583 enhanced the ACh-induced contraction and antagonized SNP-induced relaxation. NADPH diaphorase activity was assessed by a histochemistry, nitroblue tetrazolium (NTB) staining. Positive staining was observed in both circular and longitudinal muscle layers. L-arginine increased the staining, while L-NAME decreased the staining. Western blotting for nNOS proved the presence of nNOS in rat gastric smooth muscle. EFS and additional $Ca^{2+}$ increased nNOS protein expression. These results suggest that in rat stomach, both circular and longitudinal muscle layers are innervated with nitroxergic nerves which relax the gastric smooth muscle via NO-cGMP pathway.

• Clinical and Experimental Reproductive Medicine
• /
• v.25 no.1
• /
• pp.71-76
• /
• 1998

This study was carried out to examine whether the developmental capacity of bovine immature oocytes frozen ultra-rapidly using electron microscope (EM) grids and EFS30 can be obtained. As freezing solution, we used EFS30 which consisted of 30% ethylene glycol, 0.5 M sucrose, 18% ficoll and 10% FBS added in D-PBS. As criterior of oocyte viability, the rates of maturation, fertilization and embryonic development were determined. The results obtained in this experiment were summarized as follows: When ultra-rapidly frozen immature oocytes were thawed, 43.2% of them were survived. The rates of maturation (84.1%) and normal 2 pronuclei formation (57.5%) of frozen immature oocytes were not significantly different when compared to those of control (92.5, 65.0%). In addition, the rates of $\geq2$-cell (65.0%) and blastocyst formation (30.8%) of freezing group were not significantly different when compared to those of control (73.7, 35.7%). These results demonstrate that developmental capacity of frozen-thawed bovine immature oocytes can be successfully obtained when survived from the ultra-rapid freezing method using EM grid and EFS30.

• Journal of Embryo Transfer
• /
• v.9 no.1
• /
• pp.7-14
• /
• 1994

The present experiments on cryopreservation were designed to examine the effects of solution toxicity, equilibration time and cell stages on the post-thaw survival of bovine IVF embryos. The oocytes were matured in vitro(IVM) for 24 hrs. in TCM-199 supplemented with 35 $\mu$g /ml FSH, 10 $\mu$g /ml LH, 1 $\mu$g /ml estradiol-17$\beta$ and granulosa cells at 39$^{\circ}C$ under 5% $CO_2$ in air. They were fertilized in vitro(IVF) by epididymal spermatozoa treated with heparin for 24 hrs., and then the zygotes were co-cultured in vitro(IVC) with bovine oviductal epithelial cells for 7 to 9 days. The bovine IVF embryos were exposed to the EFS solution in one step at room temperature, kept in the EFS solution during different period for toxicity test, vitrified in liquid nitrogen, and thawed rapidly. 1. after the bovine blastocysts were exposed to EFS solution for 2 min. at room temperature and then they were washed in 0.5 M sucrose solution and TCM-199, they were cultured to examined cryoprotectant induced injury during exposure, Most of the embryos(95.0%) developed to reexpanded blastocoels. However, when the exposure time was extended to 5 and 10 min, these development rates dropped dramatically in 5 min. (69.5%) and 10 min. (47.4%), respectively, 2. When the bovine IVF embryos were vitrified in EFS solution after the equilibration for 1 and 2 min. exposure, The embryos to have reexpanded blastocoels following thawing, washing and culture processes were found to he 82.6 and 73.9%, respectively. However, when the exposure time was extended to 3 min, this survival rate dropped to 18.2%. The optimal time for equilibration of bovine IVF blastocysts in EFS solution seemed to he 1~2 min. 3. When the bovine IVF embryos were equilibrated for 1 min. the significantly (P<0. 05) higher post-thaw survival rates were obtained from the embryos of blastocyst stage(81.3%) than morulae stage(5. 1%). The optimal cell stage for viterification with EFS solution proven to he blastocyst stage in bovine IVF embryos. 4. The number of blastomeres of blastocyst stage was examined with nuclear staining with Hoechst 33342 during 7 to 9 days post-insemination. The cell counts of frozen bovine IVF embryos were found significantly(P$\geq$7.5 and those of the fresh embryos 76.6$\geq$7. 1, which were cultured in the sarne period and conditions as frozen embryos.

• Korean Journal of Veterinary Research
• /
• v.35 no.3
• /
• pp.459-469
• /
• 1995

As S-nitrosothiols were proposed as nitrergic carriers in vascular and nonvascular smooth muscle, we have investigated the relaxant properties of several S-nitrosothiols in the porcine retractor penis(PRP) muscle and compared them with the effects of exogenously added NO, electrical field stimulation(EFS) of NANC nerves and sodium nitroprusside(SNP). Also the influences of oxyhemoglobin and hydroquinone on the relaxant responses were investigated. In addition, effects of NO on membrane potentials and its involvement in the generation of inhibitory junction potential(IJP) were investigated with conventional intracellular microelectrode technique. The results were summerized as follows. 1. Frequency-dependent relaxations of PRP muscle were induced by EFS to NANC nerve. Tetrodotoxin($1{\times}10^{-6}M$) abolished the relaxations of PRP muscle induced by EFS, and L-NAME(($2{\times}10^{-5}M$) and methylene blue($4{\times}10^{-5}M$) inhibited the relaxations. L-NAME-induced inhibition of the relaxations was reversed by L-arginine($1{\times}10^{-3}M$), but not by D-arginine. 2. Exogenous NO($1{\times}10^{-5}-1{\times}10^{-4}M$), sodium nitroprusside(($1{\times}10^{-7}-1{\times}10^{-4}M$) induced dose-dependent relaxations of PRP muscle. All S-nitrosothiols($1{\times}10^{-7}-1{\times}10^{-4}M$) tested relaxed the PRP muscle in dose-dependent manner and the potency order was SNAP>GSNO>CysNO>SNAC. 3. Oxyhemoglobin($5{\times}10^{-5}M$) blocked the relaxation induced by exogenous NO and inhibited EFS-, S-nitrosothiols-, and SNP-induced relaxation. 4. Hydroquinone($1{\times}10^{-4}M$) also abolished the relaxations induced by exogenous NO, and reduced the relaxations induced by S-nitrosothiols, but did not affect EFS- and SNP-induced relaxations. 5. SNP($2{\times}10^{-6}-5{\times}10^{-6}M$) relaxed muscle strips but the membrane potentials were not affected. 6. EFS with several pulses(1ms, 2Hz, 80V) produced an inhibitory junction potential(IJP) with muscle relaxation. They were abolished by TTX($2{\times}10^{-6}M$). $N^G$-nitro-$_{\small{L}}$-arginine(L-NNA, $2{\times}10^{-5}M$) abolished the muscle relaxation, but had no effect on IJP.

• Korean Journal of Animal Reproduction
• /
• v.15 no.3
• /
• pp.173-177
• /
• 1991

In vitro survival of the mouse morulae frozen by vitrification method(Kasai et al., 1990) was investigated in the present study. The embryos were plunged into LN2 directly after exposure to the vitrification solutions(EFS, GFS and DFS). The results were obtained as follows. The viability of morulae after freezing and thawing was high in EFS(96.7∼100.0%) and GFS vitrification solution(93.3∼96.7%), and the lowest in DFS vitrification solution(0.00∼0.03%).

• Korean Journal of Animal Reproduction
• /
• v.23 no.1
• /
• pp.85-92
• /
• 1999

This study was designed to determine effect of cryoprotectant kinds and cell stages on OPP vitrification method in mouse embryos. The freezing speed, cryoprotectants and cell stage could affect of embryo viability following various vitrification methods. The vitrification solution used were consisting of 40% (v/v) ethylene glycol, 18% (w/v) Ficoll, 0.3 M sucrose solution in holding medium (D-PBS supplemented with 5% FCS: HM) (EFS) or 16.5% ethylene glycol , 16.5% dimethyl sulfoxide, 0.5 M sucrose in HM (EDS). The embryos were collected from oviduct at 18 h after hCG injection and then washed and cultured in mHTF medium until use. In experiment 1, the blastocysts were vitrified by OPP straw to determine the optimal vitrification solution of EFS or EDS. The post-thaw survival rates at re-expanded stage rates were significantly different between EFS and EDS (95.0 vs 100%), but at hatching stage was not different between EFS and EDS (90.0 vs 95.0%). respectively. In experiment 2, zygotes, 2-, 4-cell, morula and blastocysts were vitrified by OPP method to determine the acceptable of early stage embryos. The development rates to expanded blastocyst in zygote (70.0%) were significantly lower rather than those in 2-, 4- 8-cell, compacted morula or blastocyst (89.7, 90.0, 92.8, 97.6 or 97.5%), respectively. However, the cell number of post-thaw developed to expanded blastocyst in blastocyst and control blastocyst stage (39.6$\pm$2.81, 35.7$\pm$2.98) were significanty higher than those in zygote, 2-, 4-, 8-cell, compacted morula (29.8$\pm$3.21, 31.3$\pm$3.83, 29.3$\pm$3.58, 28.9$\pm$3.21 or 30.8$\pm$2.93). In experiment 3, the zygotes were exposed in VSl for 1, 2, and 3 min to the optimal exposed time. The cleavage rates (91.6, 88.5, 88.9%) and develop mental rates to blastocyst (83.3, 74.3 and 69.4%) depends on the exposed time in VSl were not significantly different among 1, 2, or 3 min, respectively. The cell number also were not significantly different among exposed time in VS1. respectively. These results indicate that OPP method could be useful for vitrification either EFS or EDS vitrification solution. The post-thaw survival rates at zygote were significantly lower than those at 2-, 4-, 8-cell, morula or blastocyst, respectively. The zygote stage were more sensitive rather than late stage embryos. The exposing time in VS1 for 1 min was better than that for 2 or 3 min, even it was not significantly different. The OPP vitrification method could be useful of mouse embryos either with EFS or EDS vitrification solution.

• The Korean Journal of Physiology
• /
• v.30 no.2
• /
• pp.219-229
• /
• 1996

In order to investigate intra-pancreatic cholinergic roles on insulin action in exocrine secretion, the pancreas was isolated from rats and continuously perfused with modified Krebs-Henseleit solution. Intra-arterial infusion of insulin (100 nM) or cholecystokinin (CCK, 14 pM) alone resulted in stimulation of the volume flow and amylase output. Also insulin potentiated the action of CCK in the exocrine secretion. Tetrodotoxin and atropine completely abolished the potentiating action of insulin and CCK as well as the action of insulin alone, but did not change the action of CCK alone. In order to see an effect of intra-pancreatic neural activation on the insulin action, electrical field stimulation (EFS) with parameters of 20 V, 2 msec and 8 Hz was applied to the isolated pancreas for 10 min under 2.5 or 18 mM glucose background. The EFS voltage-dependently elevated the flow rate and amylase output, and potentiated exocrine secretion in 18 mM glucose infusion compared with 2.5 mM glucose. The potentiating effects of EFS and 18 mM glucose were not observed in the streptozotocin-treated pancreas although it was perfused with 18 mM glucose. However, it was restored when the diabetic pancreas was perfused with porcine insulin(100 nM). Tetrodotoxin and atropine inhibited the pancreatic secretion induced by EFS with the background of 18 mM glucose. The results of present investigation indicate that the intra-pancreatic cholinergic tone exerts a stimulatory influence on the action of insulin in pancreatic exocrine secretion of rats.

• The Korean Journal of Pharmacology
• /
• v.19 no.2
• /
• pp.1-8
• /
• 1983

Prostaglandin(PG) is ubiquitously distributed in most mammalian tissue and their actions are complicated. Especially in autonomic nervous system, there are evidences indicating that PGs act as neuromodulators i.e., PGs, which are released in the vicinity of autonomic neuroeffector junctions, influence the release and the response of the neurotransmitter. Present study was undertaken to elucidate the interrelationship between $PGF_{2\alpha}$ and adrenergic ${\alpha}_2-receptor$ function in electrical field stimulation induced contractile response of vas deferens in rat. Male rat, weighing 150{\sim}200\;g, was sacrificed and vas deferens was obtained. The isolated vas deferens strip was placed between two platinum electrodes in temperature controlled $(37^{\circ}C)$ muscle chamber containing Tyrode's solution and the electrical field stimulation(EFS) induced contraction was recorded with Grass Polygraph(Model 7) via force displacement transducer (FT .03, Grass). The results are summarized as follows: 1) Electrical field stimulation for 1sec( 1 msec, 40 cps) induced contraction of vas deferens was completely blocked by tetrodotoxin. 2) Bretylium caused marked inhibition of the EFS-induced contraction, hut tyramine and cocaine augmented the contraction. 3) EFS-induced contraction was inhibited or little affected in distal portion of vas deferens by norepinephrine or methoxamine, but the contraction was rather augmented by the ${\alpha}-agonists$ in proximal portion. 4) Clonidine inhibited the EFS-induced contraction proportionally to the concentration in distal portion, which was blocked by yohimbine pretreatment, but in the presence of $PGF_{2\alpha}$ the blockade by yohimbine was reversed. 5) Indomethacin pretreatment reduced the effect of clonidine, but addition of $PGF_{2\alpha}$ after washing-out the indomethacin caused the contraction to the control level. From these results it is suggested that PG synthesis is a necessary step and the PG itself has a permissive role in ${\alpha}_2-adrenoceptor$ action in rat vas deferens.

• The Korean Journal of Physiology and Pharmacology
• /
• v.7 no.3
• /
• pp.169-174
• /
• 2003

${\gamma}$-Aminobutyric acid (GABA) has been reported to enhance exocrine secretion evoked not only by secretagogues but also by intrinsic neuronal excitation in the pancreas. The pancreas contains cholinergic neurons abundantly that exert a stimulatory role in exocrine secretion. This study was undertaken to examine effects of GABA on an action of cholinergic neurons in exocrine secretion of the pancreas. Intrinsic neurons were excited by electrical field stimulation (EFS; 15 V, 2 msec, 8 Hz, 45 min) in the isolated, perfused rat pancreas. Tetrodotoxin or atropine was used to block neuronal or cholinergic action. Acetylcholine was infused to mimic cholinergic excitation. GABA $(30{\mu}M)$ and muscimol $(10{\mu}M)$, given intra-arterially, did not change spontaneous secretion but enhanced cholecystokinin (CCK; 10 pM)-induced secretions of fluid and amylase. GABA (3, 10, $30{\mu}M$) further elevated EFS-evoked secretions of fluid and amylase dose-dependently. GABA (10, 30, $100{\mu}M$) also further increased acetylcholine $(5{\mu}M)$-induced secretions of fluid and amylase in a dose-dependent manner. Bicuculline $(10{\mu}M)$ effectively blocked the enhancing effects of GABA $(30{\mu}M)$ on the pancreatic secretions evoked by either EFS or CCK. Both atropine $(2{\mu}M)$ and tetrodotoxin $(1{\mu}M)$ markedly reduced the GABA $(10{\mu}M)$-enhanced EFS- or CCK-induced pancreatic secretions. The results indicate that GABA enhances intrinsic cholinergic neuronal action on exocrine secretion via the $GABA_A$ receptors in the rat pancreas.