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PubMed1985

Localization of immunoreactive synthetic atrial natriuretic factor (ANF) in the heart of various animal species.

The localization of two synthetic fragments of the C-terminal portion of atrial natriuretic factor: Arg 101-Tyr 126 which displays full biological activity and Leu 94-Arg 109 which is completely devoid of biological activity, has been investigated by immunohisto- and immunocytochemical methods in the heart of mammals (rat, mouse, guinea pig, hamster, rabbit, cat, dog, man) and nonmammalian vertebrates toad (Bufo marinus), frog (Rana catesbeiana), fish (Cyprinus carpio, Puntius schwanenfeldi, Cichlosoma biocellatum, Carrasius auratus), snake (Python reticulatus) and hen. Antibodies against the synthetic fragments of ANF were raised in rabbits and used either for immunofluorescence (Coons' technique), immunohistochemistry (unlabeled antibody technique) or immunocytochemistry (protein A-gold technique). Results obtained by immunofluorescence and by the unlabeled antibody technique were similar: antibodies against Arg 101-Tyr 126 ANF allowed visualization of granulated cardiocytes in the atria of all mammals. While the reaction was very strong in rat and mouse, it was less so in the rabbit and very weak in all other species studied including man. Antibodies against Leu 94-Arg 109 ANF produced a reaction only in the rat and mouse. In nonmammalian vertebrates, the reaction was always much stronger in atria than ventricles of all species with both antibodies.

Animals↗
PubMed1979

Poikilotherms as reservoirs of Q-fever (Coxiella burnetii) in Uttar Pradesh.

Water snakes (Natrix natrix), rat snakes (Ptyas korros), cobras (Naja naja), pythons (Python molurus), tortoises (Kachuga sp.), plankton fish (Cirrhina mrigala), frogs (Rana tigrina), toads (Bufo sp.) and monitors (Varanus indicus) were screened for evidence of Q-fever infection by the capillary agglutination test on sera to detect antibodies and/or by attempts to demonstrate Coxiella burnetii in spleen and liver samples. Sero-reactors were observed among water and rat snakes, pythons and tortoises. The organism was isolated from the spleen and liver of the monitor, tortoise and python.

Amphibians↗
PubMed1992

Protein synthesis at the blood-brain barrier. The major protein secreted by amphibian choroid plexus is a lipocalin.

Among the proteins secreted by choroid plexus of vertebrates, one protein is much more abundant than all others. In mammals, birds, and reptiles this protein is transthyretin, a tetramer of identical 15-kDa subunits. In this study choroid plexus from frogs, tadpoles, and toads incubated in vitro were found to synthesize and secrete one predominant protein. However, this consisted of one single 20-kDa polypeptide chain. It was expressed throughout amphibian metamorphosis. Part of its amino acid sequence was determined and used for construction of oligonucleotides for polymerase chain reaction. The amplified DNA was used to screen a toad choroid plexus cDNA library. Full-length cDNA clones were isolated and sequenced. The derived amino acid sequence for the encoded protein was 183 amino acids long, including a 20-amino acid presegment. The calculated molecular weight of the mature protein was 18,500. Sequence comparison with other proteins showed that the protein belonged to the lipocalin superfamily. Its expression was highest in choroid plexus, much lower in other brain areas, and absent from liver. Since no transthyretin was detected in proteins secreted from amphibian choroid plexus, abundant synthesis and secretion of transthyretin in choroid plexus must have evolved only after the stage of the amphibians.

Amino Acid Sequence↗
PubMed1987

Natriuretic hormones: comparison of renal effects.

The natriuretic properties of two small molecular weight endogenous compounds are reviewed. One may originate from the hypothalamus (natriuretic factor-NF) and the other from the cardiac atria (atrial natriuretic peptide-ANP). Differences in the intrarenal mechanisms of action of NF and ANP should be anticipated in view of the fundamentally different cellular effects of NF and ANP. NF is an inhibitor of (NaK) ATPase and inhibits active sodium transport across the isolated frog skin or toad bladder while ANP has no effect on NaK ATPase and sodium transport in vitro across the isolated anuran membrane. NF may have vasoconstrictive properties. In contrast ANP has vasorelaxing properties in some vascular beds and decreases blood pressure. Both compounds are diuretic, natriuretic and phosphaturic in intact kidneys and in kidneys with a decreased functional mass. Effects on potassium excretion are variable. For both, the increases in water and solute excretion are associated with several sites of action within the nephron. Whereas NF has little effect on glomerular filtration rate (GFR) and filtration fraction, ANP may induce impressive changes in kidney and in superficial nephron GFR, increasing the filtered load of water and solutes. ANP also increases filtration fraction changing, thereby, the peritubular physical forces of filtrate reabsorption. Both NF and ANP inhibit water and solute reabsorption in the proximal tubule. With NF, a direct tubular effect has been demonstrated in recollection micropuncture studies. In contrast, a direct epithelial effect has not been elicited with ANP in the proximal tubule.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1977

The mode of action of bumetanide: inhibition of chloride transport across the amphibian cornea.

The diuretic drug bumetanide (10(-7 M) reduced the transmural potential difference and short-circuit current across the amphibian cornea in vitro. This effect reflected a decline in the outflux (endothelial to epithelial, or tear, side) of CI, which is the direction of its active transport. There was no change in the influx. The effect was slowly reversible at 10(-4) M and was about two times as great when the drug was on the endothelial as compared to the epithelial side. Furosemide had a similar effect on CI transport, but the dose-response curves of the two drugs were not parallel. Furosemide was about 60 to 200 times less potent than bumetanide. The effect of furosemide was about five times as great when the drug was on the endothelial rather than when it was placed on the epithelial side. Thiocyanate (2 x 10(-2) M) also inhibited the active CI transport across the cornea, but it was equally effective on either side of the membrane. Bumetanide had no effect on the passive CI movements across the toad lens or frog skin in vitro. The response of the skin differs from that of furosemide and thiocyanate. These observations of the effects of bumetanide on CI transport may be relevant to the mechanism of its diuretic actions in the kidney tubule.

Animals↗
PubMedDate not supplied

[Electrotonic transmission between primary afferent fibers and the motor neurons of the isolated spinal cord of various representative amphibians].

Studies have been made of monosynaptic excitatory postsynaptic potentials elicited by stimulation of the posterior root in motoneurones of the isolated spinal cord of the frog Rana ridibunda, toad Bufo bufo, and clawed toad Xenopus laevis. In all the amphibians studied, the early component of monosynaptic EPSP was not blocked in Ca-free medium containing 2 mM Mn2+. It is suggested that electrical coupling in anuran amphibians reflects certain stage of evolution of the synaptic transmission in vertebrates.

Afferent Pathways↗
PubMedDate not supplied

[Effect of focused ultrasound on the electroreceptor system of skates and certain fish and amphibian tissues].

The effects of focused ultrasound have been investigated on the structures of electroreceptor system of the Black Sea skates (Raja clavata, Dasyatis pastinaca), as well as on the tissues of some other poikilotherms (fishes Belone belone and Solea lascaris, toad Bufo viridis, frog Rana temporaria). It was shown that focused ultrasound evokes excitation (onset of impulse activity) when applied to the pore of electroreceptors and inhibition of the activity when applied to the ampulla itself. The data obtained indicate that thermal conductivity of tissues in poikilotherms is lower than that in homoiotherms.

Animals↗
PubMed2004

Development of the nasal chemosensory organs in two terrestrial anurans: the directly developing frog, Eleutherodactylus coqui (Anura: Leptodactylidae), and the metamorphosing toad, Bufo americanus (Anura: Bufonidae).

Nearly all vertebrates possess an olfactory organ but the vomeronasal organ is a synapomorphy for tetrapods. Nevertheless, it has been lost in several groups of tetrapods, including aquatic and marine animals. The present study examines the development of the olfactory and vomeronasal organs in two terrestrial anurans that exhibit different developmental modes. This study compares the development of the olfactory and vomeronasal organs in metamorphic anurans that exhibit an aquatic larva (Bufo americanus) and directly developing anurans that have eliminated the tadpole (Eleutherodactylus coqui). The olfactory epithelium in larval B. americanus is divided into dorsal and ventral branches in the rostral and mid-nasal regions. The larval olfactory pattern in E. coqui has been eliminated. Ontogeny of the olfactory system in E. coqui embryos starts to vary substantially from the larval pattern around the time of operculum development, the temporal period when the larval stage is hypothesized to have been eliminated. The nasal anatomy of the two frogs does not appear morphologically similar until the late stages of embryogenesis in E. coqui and the terminal portion of metamorphosis in B. americanus. Both species and their respective developing offspring, aquatic tadpoles and terrestrial egg/embryos, possess a vomeronasal organ. The vomeronasal organ develops at mid-embryogenesis in E. coqui and during the middle of the larval period in B. americanus, which is relatively late for neobatrachians. Development of the vomeronasal organ in both frogs is linked to the developmental pattern of the olfactory system. This study supports the hypothesis that the most recent common ancestor of tetrapods possessed a vomeronasal organ and was aquatic, and that the vomeronasal organ was retained in the Amphibia, but lost in some other groups of tetrapods, including aquatic and marine animals.

Animals↗
PubMed1994

Relationships among ryanodine receptor isoforms expressed in vertebrate skeletal muscles based on immunologic cross-reactivities.

To clarify the relationship among ryanodine receptor isoforms from skeletal muscles of various vertebrates (alpha- and beta-isoforms with smaller and larger mobilities on SDS-polyacrylamide gel electrophoresis, respectively), we examined the cross-reactivities of those receptors from 13 animal species by Western blot analysis, using specific polyclonal antibodies raised in rabbit against the bullfrog alpha- and beta-isoforms. Anti-beta-isoform antibody showed positive reactions against skeletal muscles from carp, five species of frogs, two species of toads, and chicken, but it was negative with four mammals. Positive reactions with anti-alpha-isoform antibody, by contrast, were limited to four species of frog Rana, although the alpha-isoforms from toads (Xenopus and Bufo) also reacted very weakly. The beta-isoforms from various animal species showed almost the same mobilities on SDS-PAGE in contrast to the variable mobilities of the alpha-isoforms. These results indicate that the beta-isoform in one animal species corresponds to the beta-isoform in other species and that the beta-isoforms are highly conserved. It is also suggested that the alpha-isoforms may be related to each other, although they are more diversified.

Animals↗
PubMed2000

Effect of temperature on pH and electrolyte concentration in air-breathing ectotherms.

The aim of this study was to determine the effects of temperature upon pH, protein charge and acid-base-relevant ion exchange in air-breathing ectotherms. Plasma and skeletal muscles in cane toads (Bufo marinus) and bullfrogs (Rana catesbeiana) were examined at 30, 20 and 10 degrees C. In addition, skeletal muscle ion concentrations were examined in black racer snakes (Coluber constrictor) at 30 and 10 degrees C. Cooling the amphibians produced a reduction in most of the plasma ion concentrations (Na(+), K(+), Ca(2+), Cl(-), SO(4)(2)(-)) and in protein concentration because of increased hydration. Between 30 and 10 degrees C, total plasma osmolality fell by 14 % in the toads and by 5 % in the frogs. Plasma protein charge, calculated using the principle of electroneutrality, was unaffected by temperature, except possibly for the toads at 10 degrees C. The in vivo skeletal muscle capdelta pHi/ capdelta T ratio, where pHi is intracellular pH and T is temperature, between 30 and 20 degrees C averaged -0.014 degrees C(-)(1) in the toads and -0.019 degrees C(-)(1) in the frogs. Between 20 and 10 degrees C, there was no change in pHi in the toads and a -0.005 degrees C(-)(1) change in the frogs. The in vitro skeletal muscle capdelta pHi/ capdelta T averaged -0.011 degrees C(-)(1) in both toads and frogs. In all three species, skeletal muscle inulin space declined with cooling. Intracellular ion concentrations were calculated by subtracting extracellular fluid ion concentrations from whole-muscle ion concentrations. In general, temperature had a large effect upon intracellular ion concentrations (Na(+), K(+), Cl(-)) and intracellular CO(2) levels. The relevance of the changes in intracellular ion concentration to skeletal muscle acid-base status and protein charge and the possible mechanisms producing the adjustments in intracellular ion concentration are discussed. It is concluded that ion-exchange mechanisms make an important contribution to adjusting pH with changes in temperature.

Acid-Base Equilibrium↗
PubMed2000

The importance of glucose for the freezing tolerance/intolerance of the anuran amphibians Rana catesbeiana and Bufo paracnemis.

Several species of terrestrially hibernating frogs, turtles and insects have developed mechanisms, such as increased plasma glucose, anti-freeze proteins and antioxidant enzymes that resist to freezing, for survival at subzero temperatures. In the present study, we assessed the importance of glucose to cryoresistance of two anuran amphibians: the frog Rana catesbeiana and the toad Bufo paracnemis. Both animals were exposed to -2 degrees C for measurements of plasma glucose levels, liver and muscle glycogen content, haematocrit and red blood cell volume. Frogs survived cold exposure but toads did not. Blood glucose concentration increased from 40.35 +/- 7.25 to 131.87 +/- 20.72 mg/dl (P < 0.01) when the frogs were transferred from 20 to -2 degrees C. Glucose accumulation in response to cold exposition in the frogs was accompanied by a decrease (P < 0.05) in liver glycogen content from 3.94 +/- 0.42 to 1.33 +/- 0.36 mg/100 mg tissue, indicating that liver carbohydrate reserves were probably the primary carbon source of glucose synthesis whereas muscle carbohydrate seems unimportant. In the toads, the cold-induced hyperglycaemia was less (P < 0.05) pronounced (from 27.25 +/- 1.14 to 73.72 +/- 13.50 mg/dl) and no significant change could be measured in liver or muscle glycogen. Cold exposition had no effect on the haematocrit of the frogs but significantly reduced (P < 0.01) the haematocrit of toads from 20.0 +/- 2.1% to 5.8 +/- 1.7% due to a decreased red blood cell volume (from 1532 +/- 63 to 728 +/- 87 mm3). When toads were injected with glucose, blood glucose increased to levels similar to those of frogs and haematocrit did not change, but this failed to make them cryoresistent. In conclusion, the lack of cold-induced glucose catabolism may not be the only mechanism responsible for the freeze intolerance of Bufo paracnemis, a freeze-intolerant species.

Acclimatization↗
PubMed1977

Effects of neurotransmitters upon the discharge of secretory product from the cutaneous glands of the red-spotted newt.

The effects of sympathetic and parasympathetic agonists and antagonists on discharge of secretory product by the granular and mucous glands were examined in the red-spotted newt, Notopthalmus viridescens viridescens. Observations were made also on the South African clawed toad. Xenopus laevis, the grass frog, Rana pipiens, and the crested newt, Triturus cristatus. In contrast to the granular glands of the South African clawed toad and the grass frog, which were stimulated by alpha-adrenergic agents, those of the red-spotted newt discharge in response to acetylcholine, either in vitro when added to the Holtfreter's solution in which explants were incubated, or in vivo when injected subcutaneously. Granular glands of the crested newt were also dischared in response to subcutaneous injection of acetylcholine. Stimulation of the granular glands by acetylcholine was blocked by atopine but not by tubocurarie, indicating that the cholinergic receptors are muscarinic rather than nicotinic. The mucous glands of the red-spotted newt, on the other hand, did not discharge in response to either acetylcholine or to adrenergic agents.

Acetylcholine↗
PubMedDate not supplied

Toad atrial natriuretic peptide: cDNA cloning and functional analysis in isolated perfused kidneys.

A complementary DNA (cDNA) encoding Bufo marinus (toad) preproatrial natriuretic peptide (preproANP) was isolated by reverse-transcription polymerase chain reaction. Sequence analysis of toad preproANP cDNA revealed an open reading frame of 150 amino acid residues, which shared 72% and 66% identity with Rana catesbeiana and Xenopus laevis preproANP, respectively. The deduced amino acid sequence of toad ANP that corresponded to ANP 1-24 of R. catesbeiana and Rana ridibunda was identical, but it differed by four residues from that of X. laevis. ANP mRNA transcripts were also shown to be expressed in the toad kidney. Subsequently, the effect of frog ANP (1-24) on renal function in toad was examined using a perfused kidney preparation. The arterial infusion of frog ANP caused a dose-dependent decrease in the arterial perfusion pressure that was associated with an increase in the glomerular filtration rate (GFR) and a renal natriuresis and diuresis. The renal natriuresis and diuresis resulted predominantly from an increased GFR rather than from direct tubular effects. This study demonstrates that ANP can regulate renal function, which suggests it may be involved in overall fluid volume regulation.

Amino Acid Sequence↗