Toad

About: Toad is a research topic. Over the lifetime, 1624 publications have been published within this topic receiving 28732 citations.

The relation of changes in sodium transport to protein-bound disulfide and sulfhydryl groups in the toad bladder epithelium.

Abstract: Antidiuretic hormones were added to isolated toad bladder lobes. If the addition of hormone produced an increase in short-circuit current (SCC), the hormone also produced a highly significant decrease in cellular protein-bound disulfide groups (PBSS) with no significant change in protein-bound sulfhydryl groups (PBSH). There is a good qualitative and quantitative correlation between antidiuretic hormone-induced SCC and the reduction in PBSS. 3', l-Cycic adenosine monophosphate and aminophylline also produced an increase in SCC and a reduction in PBSS. However, with this group of substances, the decrease in PBSS is matched by an equivalent increase in PBSH. Other substances such as amphotericin B and aldosterone, which increase the SCC in the toad bladder, also cause a significant decrease in PBSS without a significant change in PBSH. The changes in SCC and PBSS show both qualitative and quantitative correlations. The results suggest that the sodium-dependent short-circuit current in the toad bladder may be related to a change in the disulfide concentration in the toad bladder epithelial cells. The altered disulfide concentration may represent a structural membrane change which is related to the changes in permeability of the cellular membrane to sodium ion.

Effects of neurohypophysial hormones on oxidative metabolism of the toad bladder in vitro.

Abstract: Oxytocin and vasopressin stimulate the metabolism of C14-labeled substrates to C14O2 by the toad urinary bladder. The hormone effect is selective: the metabolism of glucose, pyruvate, lactate and palmitate is stimulated, while that of acetate and succinate is not. The metabolic effect of these hormones is not eliminated by alterations of the ionic medium which reduce active sodium transport to very low levels. It is suggested that the neurohypophysial hormones have a direct effect on toad bladder metabolism in addition to the induction of increased permeability and increased sodium transport.

Characterization of in vivo metabolites of toad venom using liquid chromatography-mass spectrometry.

Abstract: The structures of in vivo metabolites of marinobufotoxin (marinobufagin 3-suberoylarginine ester), marinobufagin, or bufalin which are typical components of toad venom widely used as the traditional Chinese drug, Ch'an Su, are confirmed using authentic samples based on their liquid chromatography-mass spectrometric behavior. A rat is orally administered 2 mg of the previously mentioned components of toad venom, the serum is collected 30 min after the administration, extracted, and then characterized. Marinobufotoxin is hydrolyzed and further epimerized into 3-epimarinobufagin, but marinobufagin 3-hemisuberate is not detected. After the administration of marinobufagin, 3-epimarinobufagin is detected in both the male and female rats, but marinobufagin 3-sulfate is formed only in the female rats. Bufalin is metabolized to 3-epibufalin, which is found to undergo further conjugation resulting in its 3-glucuronide. Furthermore, 3-epibufalin 3-sulfate is formed only in the female rats.