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PubMed1976

Effects of chlorobutanol and bradykinin on myocardial excitation.

The negative inotropic effect of a commonly used formulation of bradykinin (Sandoz BRS-640) was found to be due to chlorobutanol, a constituent of the preparation. Solutions containing up to 100 mug of crystalline bradykinin/ml had no effect on tension or action-potential shape. Chlorobutanol (500 mug/ml) caused a 30% decrease in contraction amplitude and a 20% increase in action-potential duration. Chlorobutanol lowered conduction velocity and induced conduction failure and automaticity within isolated ventricular muscle strips. Chlorobutanol affected neither positive nor negative treppe. We conclude that bradykinin has no direct action on toad, frog, or rat myocardium. However, chlorobutanol does have direct effects on myocardial cells, acting on the cell membrane and decreasing isometric tension produced by the heart.

Acetylcholine↗
PubMed1987

Ultrastructural organization of skin: classification on the basis of mechanical role.

In our previous developmental study on skin we reported that correlations existed between the collagen fibril diameter distribution, glycosaminoglycan content and composition, and mechanical role. In this work we present new but related electron microscope data on the ultrastructure of skins from flounder, marlin, cod, frog, toad, caiman, viper, pigeon, whale and opossum. It is shown that mammalian and avian body skins generally contain relatively sharp unimodal distributions of fibril diameter consistent with a "passive" mechanical role. In contrast most reptilian and fish skins have broad, right-skewed (or bimodal) distributions of fibril diameters compatible with the exotendinous attributes required of an "active" skin. A study of the changing form of the collagen fibril diameter distribution with depth in the dermis is also reported.

Alligators and Crocodiles↗
PubMed1976

[Studies On The Parasites Of Korean Amphibia: 1. Trematodes Of Amphibians]

An investigation on the trematodes of Korean amphibians was carried out during the period from April to September of 1976. A total of 883 amphibians of 6 species were examined. These frogs, toads and salamanders were collected in the areas of the Han river side. And also these amphibians comprised 775 Rana nigromaculata, 53 Rana rugosa, 21 Hyla arborea japonica, 2 Bufo bufo gargarizans, 2 Gallula tornieri and 30 Hynobius leechi. Out of the results of this work, 7 species of trematodes belonging to 2 orders were found as follows: 1. Monogenea: Diplorchis ranae Ozaki, 1931. 2. Digenea: Diplodiscus japonicus (Yamaguti, 1936), Gorgodera japonica Yamaguti, 1936, Haematoloechus sibiricus japonicus(Yamaguti, 1936), Mesocoelium brevicaecum Ochi, 1929, Loxogenes liberum Seno,1980, Pleurogenoides japonicus (Yamaguti, 1936).

Journal Article↗
PubMed2003

Reptile-associated salmonellosis--selected states, 1998-2002.

During 1998-2002, CDC received reports from state health departments regarding Salmonella infections in persons who had contact with reptiles (e.g., lizards, snakes, and turtles). Salmonella infections usually cause gastroenteritis but can result in invasive illness (e.g., septicemia and meningitis), especially in infants and immunocompromised persons. For decades, reptiles have been known as a source for salmonellosis; however, numerous reptile owners remain unaware that reptile contact places them and other household members, including children, at greater risk for salmonellosis. Increasing evidence suggests that amphibians (e.g., frogs, toads, newts, and salamanders) also can pose risks for salmonellosis in humans. This report describes cases of reptile-associated salmonellosis in six states, offers recommendations on preventing transmission of Salmonella from reptiles and amphibians to humans, and provides an update on state regulations mandating education at pet stores about salmonellosis.

Adolescent↗
PubMed1975

[A comparative electron microscopic study of the peripheral blood leukocytes of vertebrates].

The ultrastructure of leukocytes of the peripheral blood was studied in representatives of classes of fishes (Cyprinus carpio), amphibia (Rana redibunda, Bufo bufo), reptiles (Testudo horshfield), birds (Columba livia) and mammals (Rattus norvegicus). The granules are characterized by homogeneous or heterogeneous matrix. The granules of special leukocytes (turtle) and pseudoesinophils (pigeon) have larger dimensions than those in neutrophils of other animals. The matrix of the eosinophil granules of the carp and rat contain crystalloid structures while the granules of eosinophils of amphibia, turtles and pigeons are characterized by electron dense homogeneous matrix. The basophil granules are larger and in addition to homogeneous or fine granular structure (turtle, pigeon, rat) have lamellar structure (Cyprinus carpio, frog, toad). The ultrastructural organization of agranulocytes and plasma cells of the animals studied is also described.

Animals↗
PubMed1976

The passive permeability of the skin of anuran amphibia: a comparison of frogs (Rana pipiens) and toads (Bufo marinus).

1. Efflux of Na across dorsal skin, in vitro (bathed on both sides with Ringer solution), of frogs and toads were similar, but it was greater in ventral skin from the latter. 2. The efflux of Na declined, in both species, when the external surface of ventral, but not dorsal, skin was exposed to hyposmotic solutions with a low Na concentration. This change in Na permeability was influenced by the low osmotic concentration as well as the low Na concentration. 3. Efflux of Cl was similar in both the dorsal and ventral skin preparations (Ringer on both sides) from frogs and toads. 4. Chloride efflux declined in all skin preparations exposed on the external surface to dilute Ringer solution. Solute replacement with sucrose or choline or Na2SO4 showed that the decreased Cl efflux was principally due to the low Cl concentration, though Na may also contribute. This observation suggests the presence of Cl-/Cl- exchange diffusion mechanism. 5. Cutaneous urea permeability was less in toads than frogs and the dorsal and ventral skin was similar with respect to this solute in each species. 6. The presence of external hyposmotic solutions reduced the efflux, but not the influx, of urea across frog, but not toad, skin and it appeared that solvent 'drag' may contribute to this change. 7. Diffusion permeability to water was greater in frogs than toads and in the latter the ventral skin was more permeable than the dorsal. 8. The passive permeability of amphibian skin shows considerable interspecific and regional differences to various molecules which do not necessarily parallel each other. The control of passive cutaneous permeability appears to involve a variety of specific mechanisms, the distribution of which may have evolved during their adaptation to different environments.

Animals↗
PubMed1979

Evaluation of the rate of basal oxygen consumption in the isolated frog skin and toad bladder.

In the study of active transport it is important to distinguish between oxygen consumption sustaining transepithelial transport and that responsible for other tissue functions (basal metabolism). Since amiloride blocks transepithelial active sodium transport and the associated oxygen consumption in the frog skin and toad bladder, we and others have employed this agent to evaluate the rate of basal metabolism. This technique has recently been criticized in a report that amiloride (and ouabain) increased oxygen consumption when no sodium was available for transport. We have been unable to corroborate these observations. With magnesium-Ringer as external bathing solutions, amiloride and ouabain failed to stimulate oxygen consumption. With sodium-Ringer as external bathing solution amiloride reduced oxygen consumption about 30%, to a level indistinguishable from that found on external substitution of magnesium-Ringer for sodium-Ringer. We conclude that the use of amiloride permits evaluation of the rate of basal metabolism with acceptable accuracy; a possible slight depressant effect of ouabain on basal metabolism remains to be investigated.

Amiloride↗
PubMed1997

Coexistence of alpha1 and beta adrenergic receptors in the liver of the frog Rana esculenta, the toad Bufo bufo, the lizard Podarcis sicula campestris, and the turtle Pseudemys picta elegans.

In mammals and birds the characteristics of alpha1 adrenergic receptors and their biological role in liver metabolism have been clearly described, although the predominance of receptor subtypes varies with species. In contrast, the actual presence of hepatic alpha1 adrenergic receptors in fish, amphibians, and reptiles has been questioned. Only recently has their existence been demonstrated in some fish species and also in the wood frog Rana sylvatica. The present study assessed the presence of alpha1 adrenergic binding sites on hepatic membranes of frogs, toads, lizards, and turtles using the specific alpha1 adrenergic receptor antagonist [3H]prazosin; for comparison, the binding of the specific beta adrenergic receptor antagonist [3H]CGP-12177A was evaluated in the same preparations. alpha1 Adrenergic receptors are indeed present in the liver of the ectotherms examined. Specific binding is saturable, reversible, and linear as a function of tissue concentration. The binding data indicated the presence of two classes of binding sites displaying high and low affinities with Kds in the nanomolar and micromolar ranges, respectively. The present study provides the first evidence for the presence of alpha1 adrenergic receptors in the liver of toad, lizard, and turtle while confirming their existence in another species of frog, Rana esculenta.

Adrenergic alpha-Antagonists↗
PubMed2003

Role of environmental pollutants on immune functions, parasitic infections and limb malformations in marine toads and whistling frogs from Bermuda.

Soil, water, and amphibian tissues collected between 1995 and 1999 from 15 study sites in Bermuda were analysed for pesticides and heavy metals. The most abundant pesticide residue in soil was p,p'-dichlorodiphenyldichloroethylene (DDE) which was found at all sites in concentrations ranging from 0.003 to 4.023 p.p.m. No pesticide residues were found in water. DDE was also recovered from the livers and fat bodies of marine toads (Bufo marinus) and whistling frogs (Eleutherodactylus johnstonei). Analyses of food sources consumed by these anuran species revealed residue levels of p, p'-DDE ranging from 0.05 to 0.217 p.p.m. Other soil residues included dichlorodiphenyltrichloroethane (DDT) at eight study sites, Dicofol(kelthane) at eight sites, dieldrin at five sites, and polychlorinated biphenyls (PCBs) as Arochlor 1254 and Arochlor 1260 at seven sites. Analyses of toad livers revealed significant concentrations of cadmium, chromium, copper and zinc. Livers of Bermuda toads exhibited altered hepatocytic morphology and an increased number of melanomacrophages and possible granulomas, while spleens showed a marked decrease in white pulp. Spleen cells from Bufo marinus collected at one site having high levels of cadmium exhibited a decreased B cell response to lipopolysaccharide. The incidence of trematode infection in Bufo marinus increased from 53.8% in 1995 to 90% in 1999. Deformity rates in the limbs of subadult and adult toads ranged between 15 and 25%. Examination of 1,995 newly-metamorphosed toads revealed deformity rates as high as 47%. The current comprehensive study suggests that environmental pollutants may account for immunosuppression, increased susceptibility to infections, limb malformations and possible decline in amphibian populations from Bermuda.

Animals↗
PubMed1998

Opposite effects of cooling on twitch contractions of skeletal muscle isolated from tropical toads (Leptodactylidae) and northern frogs (Ranidae).

Cooling increases the twitch force of frog skeletal muscle (Rana temporaria; Rana pipiens), but decreases the twitch force of tropical toad muscle (Leptodactylus insularis). Action potentials and intramembranous charge movement in frog and toad fibers were slowed identically by cooling. Cooling increased the integral of twitch Ca2+ detected by aequorin in frog fibers (1.4-fold), while also decreasing the peak and slowing the rate of decay. Conversely, cooling decreased the integral (0.6-fold) and the peak of twitch Ca2+ in toad fibers, without affecting the rate of decay. The difference in entire Ca2+ transients may account for cold-induced twitch potentiation in frogs and twitch paralysis in toads. In sustained contractions of toad fibers, cooling markedly decreased maximum force caused by: (i) tetanic stimulation, (ii) two-microelectrode voltage clamp steps, (iii) high [K+], or (iv) caffeine. Maximum force in sustained contractions was decreased moderately by cooling frog fibers. Rapid rewarming and simultaneous removal of high [K+] or caffeine during a sustained contraction, caused toad muscle force to rise towards the value corresponding to the warm temperature. This did not occur after removing high [K+] or caffeine from toad fibers kept in the cold. Transmission electron micrographs showed no relevant structural differences. Parvalbumins are thought to promote relaxation of frog muscle in the cold. The unique parvalbumin isoforms in toad muscle apparently lack this property.

Animals↗