BACKGROUND/AIMS: Interstitial cells play important roles in gastrointestinal (GI) neuro-smooth muscle transmission. The underlying mechanisms of colonic dysmotility have not been well illustrated. We established a partial colon obstruction (PCO) mouse model to investigate the changes of interstitial cells and the correlation with colonic motility. METHODS: Western blot technique was employed to observe the protein expressions of Kit, platelet-derived growth factor receptor-α (Pdgfra), Ca²⁺-activated Cl⁻ (Ano1) channels, and small conductance Ca²⁺- activated K⁺ (SK) channels. Colonic migrating motor complexes (CMMCs) and isometric force measurements were employed in control mice and PCO mice. RESULTS: PCO mice showed distended abdomen and feces excretion was significantly reduced. Anatomically, the colon above the obstructive silicone ring was obviously dilated. Kit and Ano1 proteins in the colonic smooth muscle layer of the PCO colons were significantly decreased, while the expression of Pdgfra and SK3 proteins were significantly increased. The effects of a nitric oxide synthase inhibitor (L-NAME) and an Ano1 channel inhibitor (NPPB) on CMMC and colonic spontaneous contractions were decreased in the proximal and distal colons of PCO mice. The SK agonist, CyPPA and antagonist, apamin in PCO mice showed more effect to the CMMCs and colonic smooth muscle contractions. CONCLUSIONS: Colonic transit disorder may be due to the downregulation of the Kit and Ano1 channels and the upregulation of SK3 channels in platelet-derived growth factor receptor-α positive (PDGFRα⁺) cells. The imbalance between interstitial cells of Cajal-Ano1 and PDGFRα-SK3 distribution might be a potential reason for the colonic dysmotility.
Abdomen ; Animals ; Apamin ; Blotting, Western ; Chloride Channels ; Colon ; Down-Regulation ; Feces ; Interstitial Cells of Cajal ; Mice ; Muscle, Smooth ; Myoelectric Complex, Migrating ; Nitric Oxide Synthase ; Platelet-Derived Growth Factor ; Silicon ; Silicones ; Small-Conductance Calcium-Activated Potassium Channels ; Up-Regulation

BACKGROUND: Bee venom (BV) has been widely investigated for potential medical uses. Recent inadvertent uses of BV based products have shown to mitigate signs of fungal infections. However, the component mediating the antifungal effect has not been identified. OBJECTIVE: This investigation compares bee venom in its whole and partial forms to evaluate the possible component responsible for the antifungal effect. METHODS: Forty-eight plates inoculated with Trichophyton rubrum were allocated into four groups. The groups were treated with raw BV (RBV), melittin, apamin and BV based mist (BBM) respectively and each group was further allocated accordingly to three different concentrations. The areas were measured every other day for 14 days to evaluate the kinetic changes of the colonies. RESULTS: The interactions of ratio differences over interval were confirmed in groups treated with RBV and BBM. In RBV, the level of differences were achieved in groups treated with 10 mg/100 µl (p=0.026) and 40 mg/100 µl (p=0.000). The mean difference of ratio in groups treated with RBV was evident in day 3 and day 5. The groups that were treated with melittin or apamin did not show any significant interaction. In BBM groups, the significant levels of ratio differences over time intervals were achieved in groups treated with 200 µl/100 µl (p=0.000) and 300 µl/100 µl (p=0.030). CONCLUSION: The the bee venom in its whole form delivered a significant level of inhibition and we concluded that the venom in separated forms are not effective. Moreover, BV based products may exert as potential antifungal therapeutics.
Antifungal Agents ; Apamin ; Bee Venoms* ; Bees* ; Melitten ; Negotiating ; Trichophyton* ; Venoms

This study was designed to examine the effects of histamine on gastric motility and its specific receptor in the circular smooth muscle of the human gastric corpus. Histamine mainly produced tonic relaxation in a concentration-dependent and reversible manner, although histamine enhanced contractility in a minor portion of tissues tested. Histamine-induced tonic relaxation was nerve-insensitive because pretreatment with nerve blockers cocktail (NBC) did not inhibit relaxation. Additionally, K+ channel blockers, such as tetraethylammonium (TEA), apamin (APA), and glibenclamide (Glib), had no effect. However, N(G)-nitro-L-arginine methyl ester (L-NAME) and 1H-(1,2,4)oxadiazolo (4,3-A) quinoxalin-1-one (ODQ), an inhibitor of soluble guanylate cyclase (sGC), did inhibit histamine-induced tonic relaxation. In particular, histamine-induced tonic relaxation was converted to tonic contraction by pretreatment with L-NAME. Ranitidine, the H2 receptor blocker, inhibited histamine-induced tonic relaxation. These findings suggest that histamine produced relaxation in circular smooth muscle of human gastric smooth muscle through H2 receptor and NO/sGC pathways.
Apamin ; Glyburide ; Guanylate Cyclase ; Histamine ; Humans ; Muscle, Smooth* ; Nerve Block ; NG-Nitroarginine Methyl Ester ; Nitric Oxide* ; Ranitidine ; Receptors, Histamine H2 ; Relaxation* ; Tetraethylammonium

Lubiprostone is a chloride (Cl-) channel activator derived from prostaglandin E1 and used for managing constipation. In addition, lubiprostone affects the activity of gastrointestinal smooth muscles. Interstitial cells of Cajal (ICCs) are pacemaker cells that generate slow-wave activity in smooth muscles. We studied the effects of lubiprostone on the pacemaker potentials of colonic ICCs. We used the whole-cell patch-clamp technique to determine the pacemaker activity in cultured colonic ICCs obtained from mice. Lubiprostone hyperpolarized the membrane and inhibited the generation of pacemaker potentials. Prostanoid EP1, EP2, EP3, and EP4 antagonists (SC-19220, PF-04418948, 6-methoxypyridine-2-boronc acid N-phenyldiethanolamine ester, and GW627368, respectively) did not block the response to lubiprostone. L-NG-nitroarginine methyl ester (L-NAME, an inhibitor of nitric oxide synthase) and 1H-[1,2,4]oxadiazolo[4,3,-a]quinoxalin-1-one (ODQ, an inhibitor of guanylate cyclase) did not block the response to lubiprostone. In addition, tetraethylammonium (TEA, a voltage-dependent potassium [K+] channel blocker) and apamin (a calcium [Ca2+]-dependent K+ channel blocker) did not block the response to lubiprostone. However, glibenclamide (an ATP-sensitive K+ channel blocker) blocked the response to lubiprostone. Similar to lubiprostone, pinacidil (an opener of ATP-sensitive K+ channel) hyperpolarized the membrane and inhibited the generation of pacemaker potentials, and these effects were inhibited by glibenclamide. These results suggest that lubiprostone can modulate the pacemaker potentials of colonic ICCs via activation of ATP-sensitive K+ channel through a prostanoid EP receptor-independent mechanism.
Alprostadil ; Animals ; Apamin ; Calcium ; Colon* ; Constipation ; Glyburide ; Interstitial Cells of Cajal* ; Membranes ; Mice* ; Muscle, Smooth ; Nitric Oxide ; Patch-Clamp Techniques ; Pinacidil ; Potassium ; Tetraethylammonium ; Lubiprostone

This study was designed to elucidate high-K+induced response of circular and longitudinal smooth muscle from human gastric corpus using isometric contraction. Contraction from circular and longitudinal muscle stripes of gastric corpus greater curvature and lesser curvature were compared. Circular smooth muscle from corpus greater curvature showed high K+ (50 mM)-induced tonic contraction. On the contrary, however, longitudinal smooth muscle strips showed high K+ (50 mM)-induced sustained relaxation. To find out the reason for the discrepancy we tested several relaxation mechanisms. Protein kinase blockers like KT5720, PKA inhibitor, and KT5823, PKG inhibitor, did not affect high K+-induced relaxation. K+ channel blockers like tetraethylammonium (TEA), apamin (APA), glibenclamide (Glib) and barium (Ba2+) also had no effect. However, N(G)-nitro-L-arginine (L-NNA) and 1H-(1,2,4) oxadiazolo (4,3-A) quinoxalin-1-one (ODQ), an inhibitor of soluble guanylate cyclase (sGC) and 4-AP (4-aminopyridine), voltage-dependent K+ channel (KV) blocker, inhibited high K+-induced relaxation, hence reversing to tonic contraction. High K+-induced relaxation was observed in gastric corpus of human stomach, but only in the longitudinal muscles from greater curvature not lesser curvature. L-NNA, ODQ and KV channel blocker sensitive high K+-induced relaxation in longitudinal muscle of higher portion of corpus was also observed. These results suggest that longitudinal smooth muscle from greater curvature of gastric corpus produced high K+-induced relaxation which was activated by NO/sGC pathway and by KV channel dependent mechanism.
Apamin ; Barium ; Carbazoles ; Contracts ; Glyburide ; Guanylate Cyclase ; Humans ; Intracellular Signaling Peptides and Proteins ; Isometric Contraction ; Muscle, Smooth ; Muscles ; Protein Kinases ; Pyrroles ; Relaxation ; Stomach ; Tetraethylammonium

In this study, we studied whether hydrogen sulfide (H2S) has an effect on the pacemaker activity of interstitial cells of Cajal (ICC), in the small intestine of mice. The actions of H2S on pacemaker activity were investigated using whole-cell patch-clamp technique, intracellular Ca2+ analysis at 30degrees C and RT-PCR in cultured mouse intestinal ICC. Exogenously applied sodium hydrogen sulfide (NaHS), a donor of hydrogen sulfide, caused a slight tonic inward current on pacemaker activity in ICC at low concentrations (50 and 100 micrometer), but at high concentration (500 micrometer and 1 mM) it seemed to cause light tonic inward currents and then inhibited pacemaker amplitude and pacemaker frequency, and also an increase in the resting currents in the outward direction. Glibenclamide or other potassium channel blockers (TEA, BaCl2, apamin or 4-aminopydirine) did not have an effect on NaHS-induced action in ICC. The exogenous application of carbonilcyanide p-triflouromethoxyphenylhydrazone (FCCP) and thapsigargin also inhibited the pacemaker activity of ICC as NaHS. Also, we found NaHS inhibited the spontaneous intracellular Ca2+ ([Ca2+]i) oscillations in cultured ICC. In doing an RT-PCR experiment, we found that ICC enriched population lacked mRNA for both CSE and CBS, but was prominently detected in unsorted muscle. In conclusion, H2S inhibited the pacemaker activity of ICC by modulating intracellular Ca2+. These results can serve as evidence of the physiological action of H2S as acting on the ICC in gastrointestinal (GI) motility.
Animals ; Apamin ; Barium Compounds ; Chlorides ; Gastrointestinal Motility ; Glyburide ; Humans ; Hydrogen ; Hydrogen Sulfide ; Interstitial Cells of Cajal ; Intestine, Small ; Light ; Mice ; Muscles ; Patch-Clamp Techniques ; Potassium Channel Blockers ; RNA, Messenger ; Sodium ; Sulfides ; Thapsigargin ; Tissue Donors

BACKGROUND AND OBJECTIVES: Voltage dependent calcium channel (VDCC) mediates calcium ion influx and controls neurotransmitter release in excitable cells. Hair cells in vertebrates cochlea are known to express L-type VDCC. The purpose of this study was to measure calcium current from hair cells to investigate basic activity and characteristics of VDCC. MATERIALS AND METHOD: We measured calcium current in hair cells of the chicken's auditory organ, the basilar papilla analogous to the mammalian cochlea, in whose L-type, dihydropyridinesensitive calcium channels predominate and in vestibular hair cells from cristae. Calcium currentthrough VDCC was isolated in voltage-clamp recording using Cesium, Tetraethylammonium, 4- aminopyridine and apamin to block the much larger potassium currents. Various concentrations of internal calcium buffer, ethylene glycol tetraacetic acid (EGTA) or 1,2-bis (o-aminophenoxy) ethane-N,N,N',N'-tetraacetic acid (BAPTA) were used. RESULTS: The higher the buffer concentration, the larger the current size were ; they were significantly larger in 10 mM of calcium buffer concentration (ANOVA, p< 0.05). There was no difference in calcium current between cochlear and vestibular hair cells. CONCLUSION: We could successfully isolate stable inward calcium current from chick hair cells. This experiment can be used as a basic method to understand neurotransmission process between hair cells and afferent neurons.
Apamin ; Calcium ; Calcium Channels ; Calcium Channels, L-Type ; Cesium ; Cochlea ; Egtazic Acid ; Ethylenes ; Hair ; Hair Cells, Vestibular ; Neurons, Afferent ; Neurotransmitter Agents ; Organ of Corti ; Potassium ; Synaptic Transmission ; Tetraethylammonium ; Vertebrates

Effects of quercetin, a kind of flavonoids, on the vasodilating actions were investigated. Among the mechanisms for quercetin-induced vasodilatation in rat aorta, the involvement with the Ca2+ activated K+ (KCa) channel was examined. Pretreatment with NE (5 micrometer) or KCl (60 mM) was carried out and then, the modulation by quercetin of the constriction was examined using rat aorta ring strips (3 mm) at 36.5degrees C. Quercetin (0.1 to 100 micrometer) relaxed the NE-induced vasoconstrictions in a concentration-dependent manner. NO synthesis (NOS) inhibitor, NG-monomethyl-L-arginine acetate (L-NMMA), at 100 micrometer reduced the quercetin (100 micrometer)-induced vasodilatation from 97.8+/-3.7% (n=10) to 78.0+/-11.6% (n=5, p<0.05). Another NOS inhibitor, L-NG-nitro arginine methyl ester (L-NAME), at 100 micrometer also had the similar effect. In the presence of both 100 micrometer L-NMMA and 10 micrometer indomethacin, the quercetin-induced vasodilatation was further attenuated by 100 micrometer tetraethylammonium (TEA, a KCa channel inhibitor). Also TEA decreased the quercetin-induced vasodilatation in endothelium-denuded rat aorta. Used other KCa channel inhibitors, the quercetin-induced vasodilatation was attenuated by 0.3 micrometer apamin (a SK channel inhibitor), but not by 30 nM charybdotoxin (a BK and IK channel inhibitor). Quercetin caused a concentration-dependent vasodilatation, due to the endothelium-dependent and -independent actions. Also quercetin contributes to the vasodilatation selectively with SK channel on smooth muscle.
Animals ; Aorta ; Apamin ; Arginine ; Charybdotoxin ; Constriction ; Endothelium ; Flavonoids ; Indomethacin ; Muscle, Smooth ; omega-N-Methylarginine ; Potassium Channels, Calcium-Activated ; Quercetin ; Rats ; Tea ; Tetraethylammonium ; Vasoconstriction ; Vasodilation

OBJECTIVEConcentration of extracellular calcium ([Ca(2+)](o)) in the central nervous system decreases substantially in different conditions. It results in facilitating neuronal excitability. The goal of this study is to examine the mechanisms of enhanced neuronal excitation in low [Ca(2+)](o) in order to provide new clues to treat the hyperexcitability diseases in clinic.

METHODSWhole-cell patch-clamp technique and neuron culture were used in the study.

RESULTSThe firing threshold of cultured hippocampal neurons decreased markedly in low [Ca(2+)](o) saline. Unexpectedly, apamine and isoprenaline, antagonists of medium afterhyperpolarization (mAHP) and slow AHP (sAHP) respectively, had no statistic significant effect on excitability of neurons. TTX at a low concentration was sufficient to inhibit I(NaP), which blocked the increase of firing frequency in low [Ca(2+)](o). It also reduced the number of spikes in normal [Ca(2+)](o).

CONCLUSIONThese results suggest that in cultured hippocampal neurons, modulation of spiking threshold but not AHP may cause the increased excitability in low [Ca(2+)](o).

Action Potentials ; drug effects ; Animals ; Apamin ; pharmacology ; Calcium ; pharmacology ; Cells, Cultured ; Dose-Response Relationship, Drug ; Electric Stimulation ; Embryo, Mammalian ; Hippocampus ; cytology ; Neurons ; drug effects ; Patch-Clamp Techniques ; Rats ; Sodium Channel Blockers ; pharmacology ; Tetrodotoxin ; pharmacology

Small and large conductance Ca2+-activated K+ (SKCa and BKCa) channels are implicated in the modulation of neuronal excitability. We investigated how changes in peripheral KCa channel activity affect mechanical sensitivity as well as the afferent fiber type responsible for KCa channel-induced mechanical sensitivity. Blockade of SKCa and BKCa channels induced a sustained decrease of mechanical threshold which was significantly attenuated by topical application of capsaicin onto afferent fiber and intraplantar injection of 1-ethyl-2-benzimidazolinone. NS1619 selectively attenuated the decrease of mechanical threshold induced by charybdotoxin, but not by apamin. Spontaneous flinching and paw thickness were not significantly different after KCa channel blockade. These results suggest that mechanical sensitivity can be modulated by KCa channels on capsaicin-sensitive afferent fibers.
Apamin ; Capsaicin ; Charybdotoxin ; Hyperalgesia* ; Neurons ; Potassium Channels, Calcium-Activated*