Showing papers on "Toad published in 1969"

The cellular specificity of the effect of vasopressin on toad urinary bladder.

Abstract: Phase and electron micrographs of toad bladders were obtained following dilution of bathing media in the presence and absence of vasopressin. Dilution of the mucosal medium alone resulted in no morphologic changes. Subsequent addition of vasopressin produced an increase in the cell volume of the granular cells, manifested by some or all of the following changes: increased area of granular cell profiles as observed in sections, rounding of the cell nucleus, displacement of the two components of the nuclear envelope, loss of nuclear heterochromatin, sacculation of the endoplasmic reticulum and the Golgi apparatus, and reduction in the electron density of the cell cytoplasm. No such morphologic changes were noted in the other cell types comprising the mucosal epithelium — the mitochondria-rich, the goblet, and the basal cells. On the other hand, dilution of the serosal bathing medium in the absence of vasopressin caused a marked increase in the cell volume of all these cell types. The results demonstrate that the action of vasopressin to enhance bulk water flow across toad bladder is exerted specifically on the apical surface of the granular cells. It is suggested that the hormonal effect on sodium transport may also be limited to the granular cells. The route of osmotic water flow and the possible role of the other mucosal epithelial cells is discussed.

Relevance of sodium transport pool measurements in toad bladder tissue for the elucidation of the mechanism whereby hormones stimulate active sodium transport

Abstract: The size of toad bladder sodium transport pool, defined as that amount of sodium of apical origin and recovered in tissue at equilibrium, was compared with sodium transport rate, derived from short-circuit current read immediately before tissue analysis. Provided certain precautions be taken, the relationship between both variables can be described by a curve starting at the intersect ofX (pool, in μEq) andY (transport, in μEq/hr) axes, with a tendency forX to increase faster thanY. Assuming sodium transport pool forms one compartment, its calculated half-life averages 2–3 min. sodium transport pool measurements are thought to shed light on mechanism of sodium transport by toad bladder because pool size was large with respect to transport rate when tissue was exposed to several inhibitors of sodium transport. Conversely, upon stimulation of activity of (substrate — depleted) preparations by glucose, a relative reduction of pool size was observed. Aldosterone, vasopressin (and adenosine 3′,5′-phosphate) increased sodium pool size and transport rate, proportionately; insulin stimulated sodium transport more than it increased pool size. Thus, insulin presumably exerts its effect at the sodium “pump” while such a site of action need not be postulated for aldosterone and vasopressin: these 2 hormones would instead induce, permeability changes faciliting sodium movement at the apical border of toad bladder epithelial cells.

Effect of Chlorpropamide on the Permeability of the Urinary Bladder of the Toad and the Response to Vasopressin, Adenosine-3″,5″-monophosphate and TheophyUine

Abstract: Chlorpropamide, which is reported to decrease urine volume and promote the formation of hypertonic urine in patients with pituitary diabetes insipidus, has no effect on the osmotic permeability of the urinary bladder of the toad, Bufo marinus. The sulfonylurea compound markedly potentiates the effect of vasopressin and theophylline, both of which increase the osmotic permeability of the toad bladder by increasing the intracellular concentration of cyclic 3′,5′-AMP. Unexpectedly, the response of the toad bladder to exogenous cyclic 3′,5′-AMP is inhibited by chlorpropamide. Therefore, the mechanism of action of chlorpropamide remains obscure. Nevertheless, it is clear that under certain conditions the drug does alter the permeability of vasopressin-sensitive tissues both in man and in the toad bladder. (Endocrinology 84: 411,1969)

The production of two molecular classes of antibody in the toad, Xenopus laevis, homologous with mammalian gamma-M (19S) and gamma-G (7S) immunoglobulins.

Abstract: A good immune response to BGG was induced in the toad, Xenopus laevis, with the production of precipitating antibody. A large amount of macroglobulin is present in normal toad serum, and forms a major peak on Sephadex G-200 gel filtration. Two classes of immunoglobulins, homologous with mammalian γM (19S) and γG (7S) antibody, are produced during the course of immunization. The conversion from 19S to 7S antibody activity occurred about a month after primary immunization.

Teleostean Urophysis: Stimulation of Water Movement across the Bladder of the Toad Bufo marinus

Abstract: An effect of material from the caudal neurosecretory system of a teleost on the isolated toad bladder is described. Urophysial breis from Gillichthys mirabilis result in dose-related water movement across the bladder. As little as one one-hundredth of a urophysis induces a threefold increase in osmotic water movement.

Stimulation of Sodium Transport Across the Isolated Toad Bladder by 1α-Hydroxycorticosterone from an Elasmobranch

Abstract: The mineralocorticoid activity of 1α-hydroxycorticosterone, an interrenal steroid in elasmobranch fish, was determined by the in vitro toad bladder bioassay. It stimulated the transport of sodium a...

The fine structure of endothelial cells of toad arteries.

Abstract: The vascular endothelia of the aortic, iliac and kidney arteries of the toad Bufo arenarumH and the frog Leptodactylus chaquensis were studied with the electron microscope The shape and size of the endothelial cells appear to depend upon whether the internal elastic membrane is stretched or contracted These cells present the following characteristics: (1) an elongated and folded nucleus, (2) large bundles of oriented filaments, (3) acid phosphatase-positive micropinocytotic vesicles, (4) small, dense, spherical granules surrounded by a single membrane These cytoplasmic granules, also studied by histochemical techniques, are of unknown nature and function

Blood Protein Variation in the Bufo americanus Species Group of Toads

Abstract: electrophoretic patterns of plasma proteins of the Bufo americanus species group of toads. This variation was sufficient to negate any possible calculation of affinities between the B. americanus and other Bufo species groups. Analyses of transferrins and hemoglobins, specifically, indicate that these components are highly variable. This paper presents my findings on the multiple molecular forms of plasma transferrin and hemoglobin in the six species of the B. americanus species group. These species are the American toad, B. americanus; the Dakota toad, B. hemiophrys; the Houston toad, B. houstonensis; the southwestern toad, B. microscaphus; the southern toad, B. terrestris; and the Rocky Mountain toad, B. woodhousii. The B. americanus group has been the subject of an intensive study of genetic compatibility relationships (W. F. Blair, 1963a). The significance of mating call as an ethological isolating mechanism in the group was discussed by W. F. Blair (1956, 1957a, 1957b, 1958), and ecological differences were found important in maintaining species integrity (A. P. Blair, 1941, 1955). Chromatograms of the parotoid gland secretions of various species in the group were examined by Hunsaker, et al. (1961) and Wittliff (1962). Abramoff, et al. (1964) used serology to test the relationships of B. americanus from islands in upper Lake Michigan. Blood proteins of some species were studied by Fox,

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 visual loss on toad, Bufos boreas, activity.

Abstract: 15 blinded Western toads, Bufos boreas, exhibited significantly less closed-field locomotor activity than those (n = 15) with normal vision. It was postulated that this decrease in activity was due to the toad's lack of an optimum arousal level.