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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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21 citations
TL;DR: Single smooth muscle cells freshly isolated from the stomach muscularis of the toad Bufo marinus were studied under direct microscopic observation using intracellular microelectrodes and there was a marked decrease in the rectification normally observed with depolarizing currents, suggesting that a K+ conductance contributes to the outward-going rectification.
Abstract: Single smooth muscle cells freshly isolated from the stomach muscularis of the toad Bufo marinus were studied under direct microscopic observation using intracellular microelectrodes. The deviation...
21 citations
TL;DR: The results suggest that Na+ and H+ are not coupled in an exchange mechanism at the mucosal surface of the cell in the absence of exogenous CO2.
Abstract: Recent results from this laboratory have shown that in the absence of mucosal Na+ and exogenous CO2, H+ excretion is reduced in the toad urinary bladder. This study was done to determine if H+ excretion is linked to Na+ reabsorption in the toad bladder. Na+ transport was inhibited by ouabain or by substitution of the sodium with choline chloride. Both of these agents produced an inhibition of H+ excretion. However, when dinitrophenol was added to stimulated CO2 production by the tissue, H+ excretion returned to control levels even though Na+ transport was still inhibited. Vasorressin, which stimulates Na+ transport in toad urinary bladder, had no effect on H+ excretion. In addition, simultaneous energies of activation were detemined for H+ excretion and Na+ reabsorption in the toad bladder. The activation energies for the two processes were significantly different. These results suggest that Na+ and H+ are not coupled in an exchange mechanism at the mucosal surface of the cell. H+ excretion, however, does appear to be limited by the endogenous CO2 production of the bladder in the absence of exogenous CO2.
21 citations
TL;DR: It was concluded that, since the pulmonary and cutaneous arteries in the toads are to some extent reciprocally innervated, the toad has the capacity to selectively perfuse either the lungs or the skin.
Abstract: 1. 1. The autonomic innervation of the cutaneous artery of a toad (Bufo marinus) was investigated by techniques of vascular perfusion and by the fluorescence histochemical technique for the demonstration of adrenergic neurons. 2. 2. The cutaneous artery was innervated by excitatory adrenergic nerve fibres originating in the cervical sympathetic connective and running in the pulmonary vago-sympathetic supply. The initial segment of the cutaneous artery was circumscribed by a moderately-dense plexus of catecholamine-containing fibres lying at the outer border of the tunica media. 3. 3. In jointly-perfused pulmonary and cutaneous artery preparations, injected acetylcholine, which caused a marked pulmonary arterial constriction, caused an increase in the proportion of total flow leaving via the initial segment of the cutaneous artery. 4. 4. It was concluded that, since the pulmonary and cutaneous arteries in the toad are to some extent reciprocally innervated, the toad has the capacity to selectively perfuse either the lungs or the skin.
21 citations
TL;DR: The rod outer segments of toad retina contain a guanylate cyclase activity that seems likely that Ca2+ plays a regulatory role on cGMP metabolism in visual excitation.
21 citations