In order to understand the phenomenon in a living cell correctly, it has been required to obtain intact responses from the cell membrane without disrupting the cytoplasmic circumstances. Gramicidin perforated patch configuration allows the electrical access to the whole cell with a minimal dialysis of cytoplasm and preventing the loss of native intracellular constituents, such as Cl-. Here, we would like to show the background of this method and the actual application of the gramicidin perforated patch recording mode on the dissociated neurons.
Cell Membrane ; Cytoplasm ; Dialysis ; Gramicidin* ; Neurons*

Objective: To investigate the effect of three preoperative anti-infective regimens on the sterility of anterior-chamber aspirates (ACA) in eyes undergoing extracapsular cataract extraction (ECCE). Methods: Ninety eyes scheduled to undergo ECCE were randomly assigned to receive one of the following preoperative anti-infective regimens: Group 1 (Control) - no additional preoperative preparation; Group 2 (Eye drop) - neomycin/ polymixin B/gramicidin eye drops applied 3 times daily for 3 days prior to surgery; and Group 3 (Lid scrub) - neomycin/polymixin B/ bacitracin ointment lid scrub applied 3 times prior to surgery. ACAs were obtained from all eyes at the conclusion of surgery and cultured. The patients were followed up for 3 months after the surgery. Results: Positive cultures developed from ACAs in 5 (16.6 percent) of 30 eyes from Group 1, in 0 of 30 from Group 2, and in 3 (10 percent) of 30 from Group 3. No eye developed endophthalmitis. Compared with the control group, preoperative neomycin/polymixin B/gramicidin eye drops significantly reduced the ACA contamination rate (p= 0.03). Conclusion: Preoperative neomycin/polymixin B/bacitracin eyedrops can improve the sterility of the anterior chamber during ECCE.
Human ; CATARACT ; ANTI-INFECTIVE AGENTS ; ENDOPHTHALMITIS ; NEOMYCIN ; GRAMICIDIN ; BACITRACIN ; CATARACT EXTRACTION ; EYE DISEASES ;

OBJECTIVE: It has been well known that alcohol can modulate several ligand-gated ion channel and voltage-gated ion channels. But the roles of alcohol in the autonomic neurons still remain unclear. In this study, thus we characterized the neuronal acetylcholine receptor (nnAChRs) and investigated the modulation of nnAChRs by ethanol (EtOH). METHODS: We used whole-cells which were acutely dissociated male rat major pelvic ganglion (MPG) neurons, and used gramicidin perforated patch clamp techniques. RESULTS: MPG neurons can be classified on the basis of the response of the soma membrane to depolarizing current pulses ; either tonic or phasic neurons. Sympathetic neurons expressing T-type Ca(2+) channels showed tonic firing pattern, while parasympathetic neurons lacking T-type Ca(2+) channels phasic firing to depolarizing current pulses. When hyperpolarizing currents were injected, sympathetic neurons produced post-anodal rebound spikes, while parasympathetic neurons were silent. Under current clamp mode, Acetylcholine (ACh) evoked significant membrane depolarization and produced subsequently marked membrane hyperporization. Under whole-cell mode, application of ACh-induced inward currents held at holding potentials below 0 mV and reversal potential was close to 0 mV, an equilibrium potential of nonselective cation channel. The ACh-activated current was blocked by methyllycaconitine (MLA ; 10 micrometer), hexamethonium (100 micrometer) and alpha-bungarotoxin (alpha-BuTx ; 100 nM), nAChRs antagonists. EtOH (40 mM) potentiated ACh-induced depolarization and hyperpolarization. EtOH also increased both alpha-BuTx-sensitive and -insensitive ACh-activated currents. Futhermore, EtOH potentiated 5-HT-activated current but had a little effect on GABA-activated current. CONCLUSION: These results suggest that EtOH modulates nnAChRs and 5-HT receptors in MPG neurons.
Acetylcholine ; Animals ; Bungarotoxins ; Carisoprodol ; Ethanol ; Fires ; Ganglia, Autonomic ; Ganglion Cysts ; Gramicidin ; Hexamethonium ; Humans ; Ion Channels ; Male ; Membranes ; Neurons ; Patch-Clamp Techniques ; Rats ; Receptors, Nicotinic* ; Receptors, Serotonin

Here we investigated the central processing mechanisms of mechanical allodynia and found a direct excitatory link with low-threshold input to nociceptive neurons. Experiments were performed on male Sprague-Dawley rats weighing 230-280 g. Subcutaneous injection of interleukin 1 beta (IL-1β) (1 ng/10 µL) was used to produce mechanical allodynia and thermal hyperalgesia. Intracisternal administration of bicuculline, a gamma aminobutyric acid A (GABAA) receptor antagonist, produced mechanical allodynia in the orofacial area under normal conditions. However, intracisternal administration of bicuculline (50 ng) produced a paradoxical anti-allodynic effect under inflammatory pain conditions. Pretreatment with resiniferatoxin (RTX), which depletes capsaicin receptor protein in primary afferent fibers, did not alter the paradoxical anti-allodynic effects produced by the intracisternal injection of bicuculline. Intracisternal injection of bumetanide, an Na-K-Cl cotransporter (NKCC 1) inhibitor, reversed the IL-1β-induced mechanical allodynia. In the control group, application of GABA (100 µM) or muscimol (3 µM) led to membrane hyperpolarization in gramicidin perforated current clamp mode. However, in some neurons, application of GABA or muscimol led to membrane depolarization in the IL-1β-treated rats. These results suggest that some large myelinated Aβ fibers gain access to the nociceptive system and elicit pain sensation via GABA(A) receptors under inflammatory pain conditions.
Animals ; Bicuculline ; Bumetanide ; Capsaicin ; gamma-Aminobutyric Acid ; Gramicidin ; Humans ; Hyperalgesia* ; Injections, Subcutaneous ; Interleukin-1beta ; Male ; Membranes ; Muscimol ; Myelin Sheath ; Neurons ; Nociceptors ; Rats* ; Rats, Sprague-Dawley ; Receptors, GABA-A ; Sensation

It has been reported that Korean red ginseng (KRG), a valuable and important traditional medicine, has varied effects on the central nervous system, suggesting its activities are complicated. The paraventricular nucleus (PVN) neurons of the hypothalamus has a critical role in stress responses and hormone secretions. Although the action mechanisms of KRG on various cells and systems have been reported, the direct membrane effects of KRG on PVN neurons have not been fully described. In this study, the direct membrane effects of KRG on PVN neuronal activity were investigated by using a perforated patch-clamp in ICR mice. In gramicidin perforated patch-clamp mode, KRG extract (KRGE) induced repeatable depolarization followed by hyperpolarization of PVN neurons. The KRGE-induced responses were concentration-dependent and persisted in the presence of tetrodotoxin, a voltage sensitive Na+ channel blocker. The KRGE-induced responses were suppressed by 6-cyano-7-nitroquinoxaline-2,3-dione (10 µM), a non-N-methyl-D-aspartate (NMDA) glutamate receptor antagonist, but not by picrotoxin, a type A gamma-aminobutyric acid receptor antagonist. The results indicate that KRG activates non-NMDA glutamate receptors of PVN neurons in mice, suggesting that KRG may be a candidate for use in regulation of stress responses by controlling autonomic nervous system and hormone secretion.
6-Cyano-7-nitroquinoxaline-2,3-dione ; Animals ; Autonomic Nervous System ; Central Nervous System ; Glutamic Acid ; Gramicidin ; Hypothalamus ; Medicine, Traditional ; Membranes ; Mice ; Mice, Inbred ICR ; Neurons ; Panax ; Paraventricular Hypothalamic Nucleus ; Patch-Clamp Techniques ; Picrotoxin ; Receptors, GABA ; Receptors, Glutamate ; Tetrodotoxin

BACKGROUND: The gonadotropin releasing hormone (GnRH) neurons perform a pivotal function in the central regulation of fertility. Somatostatin (SST) is an important neuromodulatory peptide in the central nervous system and alters neuronal activities via G protein- coupled SST receptors. A number of studies have shown that SST modulates the reproductive axis at the hypothalamic level. However, the precise action mechanisms of SST and related receptor subtypes have yet to be fully understood. In this study, we evaluated the direct effects of SST on GnRH neurons in juvenile mice. METHODS: Juvenile (postnatal days, < PND 30) GnRH-GFP transgenic mice expressing green fluorescent protein were used in this study. Acute coronal brain slices containing the preoptic area were prepared and all identified GnRH neurons were recorded using the gramicidin perforated-patch clamp technique; type II SST receptor (SSTR2) mRNA expression was evaluated via single cell reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: SST caused membrane hyperpolarization, depolarization, no response, or membrane hyperpolarization with a reduction of action potential. Most (57.7%, 30/52) of the GnRH neurons tested were hyperpolarized by SST and this SST-induced hyperpolarization was found to be concentration-dependent. The percentage of responses, membrane potential changes (MPC), and resting membrane potential (RMP) by SST were not significantly different in juvenile male and female GnRH neurons. The SST-induced hyperpolarization was maintained in the presence of tetrodotoxin (TTX), a sodium channel blocker, and an amino acid blocking cocktail (AABC) containing AP-5 (NMDA receptor antagonist), CNQX (non-NMDA glutamate receptor antagonist), picrotoxin (GABAA receptor antagonist), and strychnine (glycine receptor antagonist). SSTR2 mRNA was expressed on 10 (38%) among 26 GnRH neurons. Seglitide, an SSTR2 agonist, mimicked this SST-induced hyperpolarization (11/23 47.8%) and this response was maintained in the presence of TTX and AABC. CONCLUSION: Our data show that SST can exert potent inhibitory action against GnRH neuronal excitability via SSTR2 activation in juvenile mice.
6-Cyano-7-nitroquinoxaline-2,3-dione ; Action Potentials ; Animals ; Brain ; Central Nervous System ; Female ; Fertility ; Gonadotropin-Releasing Hormone ; Gonadotropins ; Gramicidin ; Humans ; Male ; Membrane Potentials ; Membranes ; Mice ; Mice, Transgenic ; Neurons ; Peptides, Cyclic ; Picrotoxin ; Preoptic Area ; Receptors, Glutamate ; RNA, Messenger ; Sodium Channels ; Somatostatin ; Strychnine ; Tetrodotoxin ; Axis, Cervical Vertebra

As the technologies of separation, purification and determination develop rapidly, more and more peptide compounds, which have special bioactive and medical value, have been separated from natural plants, such as oligopeptides and cyclopeptides. The chemical structures and function of these plant peptides have been researched profoundly. This paper mainly reviews the composition, structure, bioactive function and medicine value of representative plant peptides in recent years, and can give some references about research and application of plant bioactive peptides.
Animals ; Antihypertensive Agents ; chemistry ; isolation & purification ; pharmacology ; Antineoplastic Agents, Phytogenic ; chemistry ; isolation & purification ; pharmacology ; Antioxidants ; chemistry ; isolation & purification ; pharmacology ; Glutathione ; chemistry ; isolation & purification ; pharmacology ; Gramicidin ; chemistry ; isolation & purification ; pharmacology ; Humans ; Hypoglycemic Agents ; chemistry ; isolation & purification ; pharmacology ; Oligopeptides ; chemistry ; isolation & purification ; pharmacology ; Peptides ; chemistry ; isolation & purification ; pharmacology ; Peptides, Cyclic ; chemistry ; isolation & purification ; pharmacology ; Plants ; chemistry ; Plants, Medicinal ; chemistry

Natural cyclopeptides are hot spots in chemical and pharmaceutical fields because of the wide spreading bio-resources, complex molecular structures and various bioactivities. Bio-producers of cyclopeptides distribute over almost every kingdom from bacteria to plants and animals. Many cyclopeptides contain non-coded amino acids and non-pepditic bonds. Most exciting characteristic of cyclopeptides is a range of interesting bioactivities such as antibiotics gramicidin-S (2), vancomycin (3) and daptomycin (4), immunosuppressive cyclosporin-A (1) and astin-C (8), and anti-tumor aplidine (5), RA-V (6) and RA-VII (7). Compounds 1-4 are being used in clinics; compounds 5-8 are in the stages of clinical trial or as a candidate for drug research. In this review, the progress in chemical and bioactive studies on these important natural bioactive cyclopeptides 1-8 are introduced, mainly including discovery, bioactivity, mechanism, QSAR and synthesis.
Animals ; Anti-Bacterial Agents ; chemical synthesis ; chemistry ; pharmacology ; Antineoplastic Agents ; chemical synthesis ; chemistry ; therapeutic use ; Cyclosporine ; chemistry ; pharmacology ; Daptomycin ; chemical synthesis ; chemistry ; pharmacology ; Depsipeptides ; chemical synthesis ; chemistry ; therapeutic use ; Gramicidin ; chemical synthesis ; chemistry ; pharmacology ; Humans ; Immunosuppression ; Immunosuppressive Agents ; chemical synthesis ; chemistry ; pharmacology ; Molecular Structure ; Neoplasms ; drug therapy ; Peptides, Cyclic ; chemical synthesis ; chemistry ; pharmacology ; therapeutic use ; Quantitative Structure-Activity Relationship ; Vancomycin ; chemical synthesis ; chemistry ; pharmacology