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Toad
About: Toad is a research topic. Over the lifetime, 1624 publications have been published within this topic receiving 28732 citations.
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TL;DR: SSBV has a negative chronotropic, dromotropic and positive inotropic effects on isolated toad's heart; the reported effects of SSBV could be due to inhibition of Na(+)-K(+) ATPase and through ss-adrenergic receptors.
26 citations
TL;DR: It is concluded that some specific sequence of the beta subunit can influence the activation of the Na,K pump by extracellular K+ ions.
Abstract: We recently cloned the alpha 1 and the beta 1 and beta 3 subunits of the Na,K-ATPase of the toad Bufo marinus. To investigate possible functional differences between beta 1 and beta 3, we studied the potassium activation of Na-K pumps expressed in the oocyte of Xenopus laevis. Na-K pump activity was measured as K(+)-induced current in voltage-clamped oocytes. We could take advantage of the relative resistance to ouabain conferred by the Bufo alpha subunit to study specifically the exogenously expressed Na-K pumps after inhibition of the ouabain-sensitive endogenous Xenopus Na-K pumps. Coinjection of Bufo alpha 1 subunit cRNA with either beta 1 or beta 3 cRNAs results in the expression of functional Na-K pumps that share similar low ouabain sensitivity but differ in their K+ half activation constant (K1/2). Similar results were obtained with Xenopus alpha 1 and beta 1 or beta 3 subunits and with Bufo/Xenopus heterodimers. We conclude that some specific sequence of the beta subunit can influence the activation of the Na,K pump by extracellular K+ ions.
26 citations
26 citations
TL;DR: It is demonstrated that widened intercellular spaces can occur without net water transfer, possibly due to contractile activity of smooth muscle.
Abstract: Numerous studies have suggested that the lateral intercellular spaces can serve as part of the pathway for water movement across epithelia (2, 3, 5, 6, 11, 14, 15, 20, 22, 23, 24) . The primary evidence for this view has been the frequent observation in several tissues that increases in net fluid transport is accompanied by marked widening of intercellular spaces. However, recent work has demonstrated that widened intercellular spaces can occur without net water transfer, possibly due to contractile activity of smooth muscle (8, 9) . It has also been observed that the degree of stretch imposed on tissue can markedly affect the width of intercellular spaces (9) . Thus, it would be useful to follow water movement through intercellular spaces by a technique other than size changes .
25 citations
TL;DR: The results suggest that substance P is the transmitter mediating the NANC contraction, and the fibres releasing the transmitter are possibly antidromically activated, sensory afferents.
Abstract: A study was made of the innervation of the longitudinal muscle of the toad ileum with particular emphasis on the splanchnic innervation by non-adrenergic, noncholinergic (NANC) nerves.
25 citations