Showing papers on "Toad published in 1970"
192 citations
72 citations
64 citations
TL;DR: It was estimated that the reduction in urine flow was essential to the observed urea accumulation; however, an increase in net urea synthesis also appeared necessary, and the suppression of urine flow in Xenopus after transfer to saline appeared to be related to a increase in plasma sodium concentration.
Abstract: MCBEAN, RALPH L., AND LEON GOLDSTEIN. Renal function during osmotic stress in the aquatic toad Xenopus laevis. Am. J. Physiol. 2 19 (4) : 1115-1123. 1970.~Xenopus toads, which are normally aquatic and arnmonotelic, became ureotelic after maintenance in a hyperosmotic saline solution for 2-3 weeks. In addition, blood urea levels were elevated more than 15-fold, and this increase contributed significantly to achieving osmotic balance in the animals. Within a few hours after transfer of the toads to saline, urine flow fell to ${o of the rate in freshwater. By 7 days after transfer, flow had returned to about one-fourth of the freshwater level, where it remained. Changes in glomerular filtration rate paralleled those in urine flow. It was estimated that the reduction in urine flow was essential to the observed urea accumulation; however, an increase in net urea synthesis also appeared necessary. The suppression of urine flow in Xenopus after transfer to saline appeared to be related to an increase in plasma sodium concentration. Dehydration per se did not occur.
59 citations
Journal Article•
TL;DR: The primary immune response of the toad to Salmonella adelaide flagella has been analysed in terms of three immunological parameters, consistent with the hypothesis that the major patterns of differentiation and proliferation of immunologically competent cells, antigen retention and immunoglobulin structure have emerged by the phylogenetic level of anuran amphibians.
Abstract: The primary immune response of the toad, Bufo marinus, to Salmonella adelaide flagella has been analysed in terms of three immunological parameters: (a) the kinetics of appearance and morphology of cells producing specific antibodies; (b) antigen retention in one of the lymphoid organs, the jugular bodies; and (c) the nature of the immunoglobulins produced. It was found that toads responded to the bacterial antigen by producing antibody-forming cells and serum antibody in quantities comparable to those observed in mammals. In the early phase of antibody production, small and medium lymphocytes played an important role in antibody synthesis. In the later stages of the response, large cells which resembled immature plasma cells were the predominant producers of antibody. Studies on the incorporation of tritiated thymidine suggested that the majority of antibody-forming cells observed during the logarithmic phase of the response arose by division. Electron microscopic studies showed that the localization of radioactively-labelled antigen in the jugular bodies was similar to the follicular localization in mammalian lymph nodes, i.e. the antigen was associated with the surfaces of cells, rather than with intracellular sites. Although the toad was found to possess distinct classes of 18S and 7S immunoglobulins, antibody activity to this antigen was present only in the 18S molecules.
These results are consistent with the hypothesis that the major patterns of differentiation and proliferation of immunologically competent cells, antigen retention and immunoglobulin structure have emerged by the phylogenetic level of anuran amphibians.
58 citations
TL;DR: It was concluded that species differences exist for both the accumulation and metabolism of catecholamines in isolated perfused hearts of rat, mouse, guinea‐pig, pigeon and toad.
Abstract: 1. The uptake of (+/-)-(3)H-noradrenaline was studied in isolated perfused hearts of rat, mouse, guinea-pig, pigeon and toad (Bufo marinus), and the IC50 (concentration causing 50% inhibition) values for inhibition of uptake of (+/-)-(3)H-noradrenaline by (-)-noradrenaline were calculated. IC50 values ranging from 0.28 muM (rat heart) to 2.34 muM (toad heart) were found.2. In all species except the toad, (-)-noradrenaline showed a higher affinity than (-)-adrenaline for the uptake process, but the reverse was found for the toad heart.3. Mouse and pigeon hearts contained increasing amounts of metabolites of noradrenaline with increasing perfusion concentrations of noradrenaline, but the guinea-pig and toad hearts did not. The in vitro activities of noradrenaline catabolizing enzymes in heart homogenates were measured but did not explain the differences in the pattern of catabolism of noradrenaline found in the intact hearts of the different species.4. In all hearts except the toad, cocaine was an effective blocking agent for the uptake of (+/-)-(3)H-noradrenaline and led to an increase in (3)H-normetanephrine in these hearts. In the pigeon heart, cocaine plus phenoxybenzamine in the perfusate resulted in an inhibition of both (3)H-noradrenaline uptake and (3)H-normetanephrine formation.5. In guinea-pig and pigeon perfused hearts, the uptake of (3)H-noradrenaline into atria and ventricles reflected the relative concentrations of endogenous catecholamines in these regions, but this was not found for rat, mouse and toad hearts.6. It was concluded that species differences exist for both the accumulation and metabolism of catecholamines in isolated perfused hearts.
54 citations
TL;DR: An adenyl cyclase preparation derived from epithelial cells of the urinary bladder of the toad, Bufo marinus, is described and it was found that peptide analogs which inhibit the hydroosmotic effect of [8-arginine]-vasopressin on the intact bladder also inhibit the stimulation of theToad bladdercyclase preparation by vasoppressin.
Abstract: An adenyl cyclase preparation derived from epithelial cells of the urinary bladder of the toad, Bufo marinus, is described. This cyclase preparation is specifically stimulated by neurohypophyseal hormones and various synthetic analogs which evoke a hydroosmotic response in the intact bladder. The relative stimulatory effects of these compounds have been compared on the cyclase preparation and in the intact bladder. The peptide concentrations required for half-maximal stimulation (affinity) in the cell-free and intact systems were parallel; however the magnitude of stimulation produced by saturating concentrations of peptides did not correlate. Furthermore, it was found that peptide analogs which inhibit the hydroosmotic effect of [8-arginine]-vasopressin on the intact bladder also inhibit the stimulation of the toad bladder cyclase preparation by vasopressin. Prostaglandin E1, mercaptans, and disulfides, which inhibit the hormone-induced hydroosmotic response of the intact bladder, did not antagonize the stimulation of the toad bladder cyclase preparation by vasopressin.
48 citations
TL;DR: Evidence is presented which suggests that respiratory failure after intravenous injection is due to blockade of muscular nerve axons, and Animals can be resuscitated after a marginal lethal dose by artificial ventilation alone, provided this is instituted before hypoxia becomes severe.
46 citations
39 citations
TL;DR: Qualitative differences have been found in the responses of the different intestines to preincubation in vitro in sodium-free media, depending on the nature of the substituting cation.
27 citations
TL;DR: Some evidence is presented that the increased Ca influx which accompanies stimulation activates the reactions involved in the sealing process.
Abstract: The influence of stimulation on the healing-over of myocardial cells of the toad was investigated. The rate of sealing was markedly increased in beating muscles. This effect of stimulation on the healing process varied with the frequency of the stimulus and depended on the extracellular Ca concentration. Low sodium solutions increased the rate of sealing in stimulated muscles but not at rest. Some evidence is presented that the increased Ca influx which accompanies stimulation activates the reactions involved in the sealing process.
TL;DR: Chlorpromazine impairs vasopressin-induced osmotic water flow across the membrane; this impairment is associated with an irreversible increased permeability to solute and is postulated that chlorpromazine alters membrane permeability.
TL;DR: With the aid of histochemical procedures developed by Falck and Hillarp, the sympathy ganglia and the toxic gland of the lower limb of the toad were examined and the function of chromaffin cells in the sympathetic ganglia was briefly discussed.
Abstract: With the aid of histochemical procedures developed by Falck and Hillarp, the lumber sympathetic ganglia and the toxic gland of the lower limb of the toad (Bufo vulgaris japonica) were examined.1. Both SB and SC systems were considered to be adrenergic or catecholamine containing ones.2. The toxic gland of the lower limb was supposed to be innervated by adrenergic nerve fibres originated from sB neurons in the sympathetic ganglia.3. These nerve fibres which were supposed to innervate the toxic gland were assumed to innervate the smooth muscle-like cells surrounding the secretory cells of the toxic gland.4. The function of chromaffin cells in the sympathetic ganglia was briefly discussed.
TL;DR: In this article, the peroxisomes of amphibian microbodies, a group of cytoplasmic organelles enriched in catalase, are demonstrated in the toad Bufo marinus by light and electron microscopy by means of a cytochemical staining procedure.
Abstract: Microbodies (peroxisomes), a group of cytoplasmic organelles enriched in catalase, are demonstrated in the toad, Bufo marinus, by light and electron microscopy by means of a cytochemical staining procedure that demonstrates the peroxidatic activity of catalase with diaminobenzidine (DAB). Amphibian microbodies are similar to those of other classes in their fine structure and localization in hepatocytes and kidney, where they are prominent in the proximal tubular cells. Nucleoids are present only in renal microbodies. In the proximal renal tubule an unusual group of large brown granules are identified as lysosomes by their acid phosphatase, β-glucosaminidase and β-glucuronidase activities.
01 Jan 1970
Journal Article•
TL;DR: Acetylcholine, eserine, pilocarpine, phospholine iodide, and atropine did not alter the movements of Na or K across intact or decapsulated lenses of the toad.
Abstract: The lens of the toad Bufo marinus, like that of mammals, slowly gains Na and loses K when incubated in vitro. This process is facilitated by a low temperature (5° C), iodoacetate, cyanide, or ouabain. The ratio of Na/K exchange is about 1.5. Decapsulation of the lens (following brief incubation in collagenase) did not change its ionic content. Such lenses maintained their Na levels in vitro better than normal ones and lost K at a similar rate, so that the Na/K exchange was about 0.7. Ouabain still exerts its effects in the decapsulated lens, while ethacrynic acid facilitated Na accumulation more so than in the intact tissue. Ethacrynic acid did not alter K loss. Acetylcholine, eserine, pilocarpine, phospholine iodide, and atropine did not alter the movements of Na or K across intact or decapsulated lenses of the toad. Demecarium promoted extra accumulation of Na in both situations.
TL;DR: An attempt is made to evaluate the phytochemical properties of citric acid and its role in the formation of sticky substance in the muscle of toad mouth.
Abstract: INCREASED UPTAKE AND EFFLUX OE CALCIUM WITH ACETYLCHOLINE STIMULATION IN SMOOTH MUSCLE OF TOAD STOMACH