In recent years, there has been a rapid decrease in amphibian populations worldwide, and infectious diseases have been associated with this decline. Diseased frogs inhabiting Korea were collected from fields, and the diseases were identified by morphological and molecular analyses. Two fungal diseases-saprolegniasis and chromomycosis-were detected in the frogs. Saprolegniasis caused by Saprolegnia spp. was found in Rana plancyi chosenica from Gangwon-do and Rana huanrenensis from Chungbuk. Chromomycosis, which is caused by infection with Cladosporium cladosporioides, was detected in Rana catesbeiana from Busan.
Amphibians ; Chromoblastomycosis ; Cladosporium ; Communicable Diseases ; Korea ; Rana catesbeiana ; Ranidae ; Saprolegnia

It already has been known that various ions were participated in phototransduction mechanism of the vertebrate photoreceptor during the visual adaptation. The vitreous humor(VH)contains certain amount of Na+, K+ and Ca++ as well. However, the roles of these ions are unknown except functioning of metabolic process. Our preliminary electroretinogram(ERG) experiments suggested that the permeability of these ions has light dependent activity during the light illumination. We have supported this suggestion more tangibly by trying out various experiments with bullfrog eyes as a reference of visual adaptation. The results are summarized as follows: 1)According to our atomic absorption spectroscopic measurements, the concentration of Na+, K+ and Ca++ in light adapted VH was higher than that of dark adapted VH. This result indicated that the light-dependention transport systems which affect the ionic movements might be in internal limiting membrane(ILM). 2)The amplitude of ERG b-wave was reduced by concentration decrement of Na+ and concentration increment of K+ respectively. On the other hand, the elimination of Ca++ within ringer solution resulted in b-wave amplitude increment. 3)Treatment of Na+ hannel blockers(TTX, STX)and K+ channel blockers(Ba++, Cd++, Cs+, 4-AP and TEA)in the vitreous humor side induced the increment and the decrement of b-wave response respectively. Taken together, these results suggest that the light dependent Na+ K+ channels exist in the ILM of vertebrate retina which participates visual adaptation.
Absorption ; Hand ; Ions ; Light Signal Transduction ; Lighting ; Membranes* ; Metabolism ; Permeability ; Photoreceptor Cells, Vertebrate ; Rana catesbeiana ; Retina ; Vertebrates* ; Vitreous Body

OBJECTIVETo study the in vitro mucosal permeation properties of paeonol and the factors that affect such permeability.

METHODBullfrog skin was selected as the permeation model, and the modified Franz diffusion cell was adopted to investigate the percutaneous adsorption in vitro. Content of paeonol was quantified by HPLC. Kinds of receiving solution, parts of bullfrog skin and impacts of drug concentration on percutaneous adsorption in vitro were systematically studied.

RESULTPercutaneous permeation of paeonol was to some extent affected by osmotic pressure and pH value of the receiving solution. Abdominal skin, lateral abdominal skin and dorsal skin, with the permeability coefficient form high to low, had great influence on the permeation of paeonol. There existed a good percutaneous permeation of paeonol. And the relationship between the cumulative permeability rate and time was coincided with the first order kenetical process.

CONCLUSIONTake the in vitro abdominal skin of bullfrog as the permeation model, some similarities are revealed between in vitro percutaneous permeation of paeonol and mucosal adsorption.

Acetophenones ; metabolism ; Animals ; Chromatography, High Pressure Liquid ; Hydrogen-Ion Concentration ; In Vitro Techniques ; Mucous Membrane ; metabolism ; Osmotic Pressure ; Permeability ; Rana catesbeiana ; metabolism ; Skin ; metabolism

PURPOSE: The purpose of this study was to clarify the effects of zinc treatment and hypothermia on visual adaptation and visual sensitivity in bullfrogs (Rana catesbeiana), which are poikilothermal animals capable of adjusting quickly to environmental temperature changes. METHODS: The effects of both zinc treatment and hypothermia on visual sensitivity were studied by using electroretinogram (ERG) recording and absorption spectra scanning before and after zinc and TSQ (N-[6-methoxy-8-quinolyl]-p-toluene sulfonamide) treatment, with or without temperature changes. RESULTS: In spite of malnutrition due to hibernation, the optimal zinc concentration effect was obtained at 10-4 M (10-2 M 200 microliter ZnCl2 in 20 microliter Ringer's solution) according to ERG recording. After zinc treatment and hypothermia induction, increments of all ERG components and thresholds were taken by ERG recording. These results showed that both zinc treatment and hypothermia may increase visual sensitivity during visual adaptation. In spectral scans, the absorbance increment due to zinc treatment and hypothermia was shown over the whole spectral range (400~750 nm), and it was especially prominent at alpha-peak (about 500 nm). In addition, there was a decrease in absorption differences between dark adaptation and light adaptation after zinc treatment. Furthermore, according to the visual sensitivity decrement using TSQ as a zinc specific chelator, this visual sensitivity increase was shown to be caused by zinc. CONCLUSIONS: As the results suggest, both zinc treatment and hypothermic effects may improve visual sensitivity by promoting rhodopsin regeneration and inhibiting rhodopsin bleaching induced by light illumination. Zinc may activate the enzyme activity of retinol dehydrogenase and phosphodiesterase, while hypothermic effects may improve precursor transport, which is required for rhodopsin regeneration, by tightening membrane adhesion between retinas and retinal pigment epithelia. In addition, we believe that zinc treatment and hypothermic effects may work synergistically to accelerate visual sensitivity during visual adaptation.
Absorption ; Adaptation, Ocular ; Animals ; Dark Adaptation* ; Hibernation ; Hypothermia ; Lighting ; Malnutrition ; Membranes ; Oxidoreductases ; Rana catesbeiana ; Regeneration ; Retina* ; Retinaldehyde ; Rhodopsin ; Vertebrates* ; Vitamin A ; Zinc*

Bitter taste is an important warning sign for animals that food is poisonous. The transduction mechanism of bitter taste is still a contradictory matter among researchers. The major current hypothesis, based mainly on biochemical data, involves metabotropic cascades, either via cytoplasmic cyclic nucleotide monophosphate (cNMP) or via IP3. The former hypothesis involves cytoplasmic cNMP. It has been shown that a taste receptor cell expresses a specific G protein (McLaughlin et al, 1992) that activates phosphodiesterase leading to the decomposition of cNMP (Price, 1973; Ruiz-Avila et al, 1995). The frog taste receptor cell has a cationic channel, which is kept closed at a high cNMP concentration. Bitter stimuli reduce the cNMP concentration and release the cationic channel from the closed state (Kolesnikov & Margolskee, 1995). The latter hypothesis involves the cytoplasmic inositol 1,4,5-trisphosphate (IP3) as a second messenger. This hypothesis proposes that a bitter substance increases the cytoplasmic IP3 concentration by activating a G protein and phospholipase C. IP3 triggers Ca2+ release from the endoplasmic reticulum, which in turn directly or indirectly induces transmitter release from the taste receptor cells (Akabas et al, 1988; Hwang et al, 1990; Spielman et al, 1994, Spielman et al, 1996). We found recently an entirely different mechanism for the bitter taste transduction. We excised a patch membrane from an isolated taste receptor cell of the fungiform papillae of the bullfrog (Tsunenari et al, 1996, 1999) and recorded in the outside-out configuration. The patch pipette was filled with a solution containing 120 mM CsCl, 2 mM Na2-EGTA and 10 mM Na-HEPES. The outside of the patch membrane was exposed to the 120 mM NaCl solution containing 120 mM NaCl and 2 mM Na-HEPES. Thus, on the cytoplasmic face of the patch membrane none of the second messenger candidates or their precursors (eg. cyclic nucleotide, IP3, Ca2+, ATP and GTP) was present.
Adenosine Triphosphate ; Animals ; Cytoplasm ; Endoplasmic Reticulum ; GTP-Binding Proteins ; Inositol 1,4,5-Trisphosphate ; Membranes ; Rana catesbeiana ; Second Messenger Systems ; Type C Phospholipases

In order to affirm the cardioactive components in Fuzi, we identified a group of aminoalcohol- diterpenoid alkaloids in Fuzi using ultra high-performance liquid chromatography coupled with electrospray ionization mass spectrometer (UPLC-ESI-MS) method. Among a total of forty-one isolated ingredients, thirteen major aminoalcohol-diterpenoid alkaloids were identified by comparing their retention times and MS spectra with those of the reference substances. Moreover, Fuzi samples from different places of origin and with different processing methods were examined and their components displayed a pattern of high similarity, though the relative abundance varies probably due to their different processing methods. Furthermore, the cardiac effect of each identified alkaloid was individually evaluated using the isolated bullfrog heart perfusion experiment. Among the thirteen aminoalcohol diterpenoid alkaloids tested, six of them significantly enhanced the amplitude rates. Taken together, we affirm that the cardioactive components in Fuzi are aminoalcohol-diterpenoid alkaloids, shedding light on future studies of the mechanisms and development of these cardioactive compounds.
Aconitum ; chemistry ; Alkaloids ; chemistry ; Amino Alcohols ; chemistry ; Animals ; Cardiotonic Agents ; chemistry ; Chromatography, High Pressure Liquid ; Drugs, Chinese Herbal ; chemistry ; Heart ; drug effects ; In Vitro Techniques ; Plant Extracts ; chemistry ; Rana catesbeiana ; Spectrometry, Mass, Electrospray Ionization

OBJECTIVEA few investigations have been reported about pretectal suppressive influences on the optic tectum of frog, but characteristics of tectal activity to pretectal input are left unknown. We made intracellular recordings to demonstrate the unexpected complexity in synaptic mechanisms involved in the suppressive influences of pretecal stimulation on the tectal cells.

METHODSIn the present study, we investigated the neuronal activity evoked by pretectal (Lpd/P) nuclei stimulation using intracellular recording technique.

RESULTSThe pretectal stimulation mainly elicited two types of responses in the ipsilateral tectum: an excitatory postsynaptic potential (EPSP) followed by an inhibitory postsynaptic potential (IPSP) and a pure IPSP. The latter predominated in the tectal cells responding to pretectal stimulation. In a few cells, biphasic hyperpolarization appeared under stronger stimulus intensities. The spikes of tecto-pretectal projecting cells elicited by antidromical stimulation were recorded in the ipsilateral tectum, which revealed reciprocal connections between the tectum and particular pretectal nuclei. The synaptic natures underlying pretecto-tectal information transformation have also been demonstrated. EPSPs with short latencies were concluded to be monosynaptic. Most IPSPs were generated through polysynaptic paths, but monosynaptic IPSPs were also recorded in the tectum. Nearly 98% of impaled tectal cells (except for antidromically projecting cells) showed inhibitory responses to pretectal stimulation.

CONCLUSIONThe results provide strong evidence that pretectal cells broadly inhibit tectal neurons as that has suggested by behavioral and extracellular recording studies.

Animals ; Electric Stimulation ; Excitatory Postsynaptic Potentials ; physiology ; Female ; Inhibitory Postsynaptic Potentials ; physiology ; Male ; Neural Inhibition ; physiology ; Neural Pathways ; cytology ; physiology ; Neurons ; physiology ; Rana catesbeiana ; physiology ; Superior Colliculi ; cytology ; physiology

Under some pathological conditions as bile flow obstruction or liver diseases with the enterohepatic circulation being disrupted, regurgitation of bile acids into the systemic circulation occurs and the plasma level of bile acids increases. Bile acids in circulation may affect the nervous system. We examined this possibility by studying the effects of bile acids on gating of neuronal (N)-type Ca2+ channel that is essential for neurotransmitter release at synapses of the peripheral and central nervous system. N-type Ca2+ channel currents were recorded from bullfrog sympathetic neuron under a cell-attached mode using 100 mM Ba2+ as a charge carrier. Cholic acid (CA, 10(-6) M) that is relatively hydrophilic thus less cytotoxic was included in the pipette solution. CA suppressed the open probability of N-type Ca2+ channel, which appeared to be due to an increase in null (no activity) sweeps. For example, the proportion of null sweep in the presence of CA was ~40% at +40 mV as compared with ~8% in the control recorded without CA. Other single channel properties including slope conductance, single channel current amplitude, open and shut times were not significantly affected by CA being present. The results suggest that CA could modulate N-type Ca2+ channel gating at a concentration as low as 10(-6) M. Bile acids have been shown to activate nonselective cation conductance and depolarize the cell membrane. Under pathological conditions with increased circulating bile acids, CA suppression of N-type Ca2+ channel function may be beneficial against overexcitation of the synapses.
Bile ; Bile Acids and Salts ; Calcium Channels, N-Type ; Cell Membrane ; Central Nervous System ; Cholic Acid ; Enterohepatic Circulation ; Fees and Charges ; Ganglia, Sympathetic ; Liver Diseases ; Nervous System ; Neurons ; Neurotransmitter Agents ; Plasma ; Rana catesbeiana ; Synapses

Correlated firings among neurons have been extensively investigated; however, previous studies on retinal ganglion cell (RGC) population activities were mainly based on analyzing the correlated activities between the entire spike trains. In the present study, the correlation properties were explored based on burst-like activities and solitary spikes separately. The results indicate that: (1) burst-like activities were more correlated with other neurons' activities; (2) burst-like spikes correlated with their neighboring neurons represented a smaller receptive field than that of correlated solitary spikes. These results suggest that correlated burst-like spikes should be more efficient in signal transmission, and could encode more detailed spatial information.
Action Potentials ; Animals ; Computer Simulation ; Darkness ; Electrophysiology ; In Vitro Techniques ; Light ; Patch-Clamp Techniques ; Postsynaptic Potential Summation ; Rana catesbeiana ; physiology ; surgery ; Retina ; physiology ; Retinal Ganglion Cells ; physiology ; Retinal Neurons ; physiology ; Signal Transduction