PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “FROGS AND TOADS”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 379 records · Page 21Linked to original sources
PubMed1994

Poorly selective cation channels in the apical membrane of A6 cells.

This paper describes a Ca(2+)-blockable, poorly selective cation pathway in the apical membrane of A6 epithelia. This pathway has properties that resemble the cation-selective channels in the toad urinary bladder and frog skin. Transepithelial short circuit currents (Isc) and power density spectra (PDS) of the fluctuations in current were recorded. The basolateral surface of the tissues was exposed to Cl- or SO4(2-) solutions with Na+ as the major cation. Ca(2+)-blockable inward oriented currents and Lorentzian noise were recorded with isotonic (215 mosmol/kg) mucosal Cl- and hypotonic (144 mos-mol/kg serosal SO4(2-) solution with Na+, K+, Rb+ or Cs+ as the major mucosal cation. Experiments with mucosal K+ demonstrated that the cation-selective channel was markedly activated by serosal hypotonicity. Effects of an increased electrical driving force were excluded on the basis of the results obtained with microelectrode experiments and transepithelial voltage clamping. Cell volume expansion induced by isotonic replacements of serosal sucrose by glycerol or urea also activated the cation-selective pathway. Furthermore, the presence of Cl- in the mucosal solution was a prerequisite for a sustained response to hypotonicity or replacements of the organic compounds. Moreover, we found that the cation-selective channels are mainly expressed in the cells during the early period of epithelial growth.

Animals↗
PubMed2006

Comparative developmental toxicity of nickel to Gastrophryne carolinensis, Bufo terrestris, and Xenopus laevis.

The early embryo-larval developmental toxicity of nickel (Ni) to 3 amphibian species, Xenopus laevis (South African clawed frog), Bufo terrestris (southern toad), and Gastrophryne carolinensis (eastern narrow-mouthed toad), was evaluated using a modified FETAX model. Studies were initiated from late blastulae stage (Nieuwkoop and Faber [NF] stage 10 or Gosner stage 12) and completed at a common embryological-based test termination point, which represented the completion of the major stages of organogenesis (NF stage 46 for Xenopus or Gosner stage 26 for the toads). Results indicated that, in terms of lethality, G. carolinensis was the most sensitive and X. laevis was the least sensitive of the species tested. The 4-d LC50 in X. laevis value was approximately 7.2- and 2.8-fold greater than the G. carolinensis and B. terrestris, respectively. In terms of malformation, X. laevis was the most sensitive and B. terrestris was the least sensitive of the species tested. The 7-d EC50 (malformation) in B. terrestris was 10.6- and 7.0-fold greater than X. laevis or G. carolinensis, respectively. The chronic value (ChV) for growth in X. laevis was nearly 4.5-fold less than the ChV for growth determined for B. terrestris. As with the malformation endpoint, X. laevis was more sensitive than the other species, which were nearly equisensitive. Overall, the present study provides new data regarding the toxicity of Ni to larval amphibian species, which may be useful in the establishment of new aquatic life criteria for Ni.

Abnormalities, Drug-Induced↗