Toad

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

Species differences in the ouabain sensitivity of the small intestine in contractile response.

Abstract: Ouabain was examined for effect on the mechanical response of the ileum isolated from eleven animal species, dog, cat, rabbit, guinea pig, rat, vole, mouse, cock, pigeon, frog and toad. In isotonic recording, ouabain induced a sustained contraction in ileum isolated from some species. It caused a transient contraction on following by a relaxation in others. The ouabain sensitivities of a contractile response in the ilea from eleven species, as demonstrated by the estimation of ED50, was divided into four groups. That is, a high sensitive group; frog (ED50=9.0×10-8M), cat (9.3×10-8M), pigeon (3.5×10-7M) and cock (5.1×10-7M), a sensitive group; rabbit (1.1×10-6M), vole (2.3×10-6M) and guinea pig (2.7×10-6M), a low sensitive group; mouse (1.7×10-5M) and rat (9.7×10-5M) and an insensitive group; toad (>10-3M). Although ED50 in the dog was not able to be calculated, its sensitivity seems to belong to the high sensitive group. On the other hand, ED50 of acetylcholine (Ach) in thc ilea, isolated from these species were estimated in a narrow range of concentration from 5×10-9M to 5×10-8M. There were species differences in ouabain sensitivity for ileal contractile response but not in Ach sensitivity. A distinct correlation was found between the mechanical response to ouabain and the inhibitory potency of ouabain for Na, K-ATPase reported by Repke et al. These results seem to confirm that ouabain may induce a contraction by a mechanism which inhibits an electrogenic Na pump or Na, K-ATPase in the intestinal smooth muscle cell and which induces a depolarization.

Effect of bromocriptine on the larval skin of the green toad, Bufo viridis viridis leurenti.

Abstract: AL-ADHAMI M. A., QAR J. 2007. Effect of Bromocriptine on the Larval Skin of the Green Toad, Bufo viridis viridis Leurenti. Folia biol. (Krakow) 55: 41-46. In the premetamorphic larval green toad, B. viridis viridis, as in other anurans, the skin is made up of a fibrous dermis and an epidermis of stratified epithelium. The effects of bromocriptine, an antiprolactin drug, on the premetamorphic skin of B. viridis viridis was examined. Bromocriptine, dissolved in rearing water at four different concentrations, induced a number of changes in the skin of treated tadpoles. In rough sequence of appearance, these changes include: retraction of the melanocyte dendrites, synchronous burst of the apical vesicles of the superficial epithelial cells, gradual disappearance of the melanosomes from the epithelial cells and widening of the intercellular spaces. In addition, macrophages appeared in the superficial dermis amongst the retracted melanocytes. White crystals were observed on the skin surface and similar crystals were ingested by the macrophages. Prolonged treatment with bromocriptine resulted in hypertrophy and extraction of some epidermal cells. Deep melanocytes of the mesenteries were not affected by bromocriptine-treatment indicating that the drug did not penetrate deep into the tadpole tissue. Whether the macrophages observed in the dermis were recruited from deeper tissues or were converted melanocytes is another issue in need of study.