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Abstract:

1. The water uptake (WU), urine production (U), overall water balance (WB) and body weight variations (bwv) were measured in normal (N) as well as in totally hypophysectomized, retrochiasmatic sectioned, infundibulum lesioned (HR) toads. Groups of animals were studied while adapted to tap water and during immersion in sucrose solutions of different concentrations (46, 92, 138, 220 and 230 mM). Subsequently the rate of water uptake (Jw) and the osmotic permeability coefficient (LPD) were calculated. Also the effect on these variables of the subcutaneous administration of a non-competitive α-blocker (Phenoxybenzamine: POB) was tested. 2. No correlation was found in normal controls between the osmotic pressure outside and WU, U, WB, bwv or Jw. Jw remained relatively stable from 46 to 184 mOsm of external osmotic pressure, apparently due to a compensatory increase of LPD in the same group. 3. At a higher concentration of the external environment (220 mM) a drastic increase in LPD was observed in normal animals but the effect was markedly attenuated in HR animals. 4. Alpha-adrenergic blockade with POB induced a significant and almost constant increase in WU, WB and Jw in normal animals in solutions up to 138 mM sucrose. These effects ceased when the external concentration reached 170 mM. A concomitant and stable increment in LPD was also observed. These values provide an indirect estimate of the adrenergic factor controlling water movements across the skin of the toad in vivo (Segura et al. 1982b), which appear to be osmotically independent within this range. The copious increase in WU due to adrenergic blockade was unaffected by amiloride (10-4 M), so water transport cannot be linked with sodium transport. 5. The present results appear to establish that: (a) Permeability of the skin to water is related to the osmolarity of the external environment in the normal toad; (b) hypothalamic-hypophyseal mechanisms seem only in part to account for this responsiveness; (c) normal toads are able to compensate in some degree for the reduction in water uptake caused by an increase in the osmolarity of the external environment by an increase in the osmotic permeability of the skin. © 1984 Springer-Verlag.

Registro:

Documento: Artículo
Título:Role of the CNS in the control of the water economy of the toad Bufo arenarum Hensel - III. Skin permeability increases to raised osmotic pressure of the external 'milieu'
Autor:Segura, E.T.; Reboreda, J.C.; Skorka, A.; Cuello, M.E.; Petriella, S.
Filiación:Laboratorio de Fisiología del Comportamiento, Instituto de Biología y Medicina Experimental, Obligado 2490, Buenos Aires, 1428, Argentina
Año:1984
Volumen:154
Número:6
Página de inicio:573
Página de fin:578
DOI: http://dx.doi.org/10.1007/BF00684410
Título revista:Journal of Comparative Physiology B
Título revista abreviado:J Comp Physiol B
ISSN:01741578
Registro:https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_01741578_v154_n6_p573_Segura

Referencias:

  • Barker Jørgensen, C., The amphibian wate economy with special regard to the effect of neurohypophyseal extracts (1950) Acta Physiol Scand, 22, pp. 1-79
  • Benedictis, E.M., Lacaz-Vieira, F., Electrolytes control flows of water across the apical barrier in toad skin: the hydrosmotic salt effect (1982) Membrane Biol, 67, pp. 125-135
  • Bentley, P.J., The effects of vasopressin on water uptake of the toad, Bufo marinus, while bathed in different hypotonic solutions (1957) Journal of Endocrinology, 16, pp. 126-134
  • De Sousa, R.C., Grosso, A., Osmotic water flow across the abdominal skin of the toad Bufo marinus: effect of vasopressin and isoprenaline (1982) J Physiol (London), 329, pp. 281-296
  • Dicker, S.E., Elliot, A.B., Water uptake by Bufo melanostictus as affected by osmotic gradients, vasopressin and temperature (1967) J Physiol (London), 190, pp. 359-370
  • Gallardo, R., Pang, P.K.T., Sawyer, W.H., Neural influences on bullfrog renal functions (1980) Proc Soc Exp Biol Med, 165, pp. 233-240
  • Kedem, O., Katchalsky, A., Thermodynamic analysis of the permeability of biological membranes to non-electrolytes (1958) Biochem Biophys Acta, 27, pp. 229-246
  • Pang, P.K.T., Uchiyama, M., Sawyer, W.H., Endocrine and neural control of amphibian renal functions (1982) Fed Proc, 41, pp. 2365-2370
  • Rey P (1937) Recherches expérimentales sur l'économie de l'eau chez les batraciens. Diss Paris (quoted by Barker Jørgensen C 1950); Schmajuk, N.A., Segura, E.T., Behavioral regulation of water balance in the toad Bufo arenarum (1982) Herpetologica, 38, pp. 296-301
  • Segura ET, Bandsholm UC, Bronstein A (1980) Neural control of water intake across the skin of the toad. VIIth Int Conf Physiol Food and Fluid Intake, “IUPS”, Warsaw, July 7–10, 1980, Volume of Abstracts, p 101; Segura, E.T., Bandsholm, U.C., Bronstein, A., Woscoboinik, D., Role of the CNS in the control of the water economy of the toad Bufo arenarum Hensel. I. Effects of handling, brain lesions, anesthesia and reversible coma upon water uptake, urine production and overall water balance (1982) J Comp Physiol, 146, pp. 95-100
  • Segura, E.T., Bandsholm, U.C., Bronstein, A., Role of the CNS in the control of the water economy of the toad Bufo arenarum Hensel. II. Adrenergic control of water uptake across the skin (1982) J Comp Physiol, 146, pp. 101-106
  • Shoemaker, V.H., Nagy, K.A., Osmoregulation in amphibians and reptiles (1977) Annu Rev Physiol, 39, pp. 449-471

Citas:

---------- APA ----------
Segura, E.T., Reboreda, J.C., Skorka, A., Cuello, M.E. & Petriella, S. (1984) . Role of the CNS in the control of the water economy of the toad Bufo arenarum Hensel - III. Skin permeability increases to raised osmotic pressure of the external 'milieu'. Journal of Comparative Physiology B, 154(6), 573-578.
http://dx.doi.org/10.1007/BF00684410
---------- CHICAGO ----------
Segura, E.T., Reboreda, J.C., Skorka, A., Cuello, M.E., Petriella, S. "Role of the CNS in the control of the water economy of the toad Bufo arenarum Hensel - III. Skin permeability increases to raised osmotic pressure of the external 'milieu'" . Journal of Comparative Physiology B 154, no. 6 (1984) : 573-578.
http://dx.doi.org/10.1007/BF00684410
---------- MLA ----------
Segura, E.T., Reboreda, J.C., Skorka, A., Cuello, M.E., Petriella, S. "Role of the CNS in the control of the water economy of the toad Bufo arenarum Hensel - III. Skin permeability increases to raised osmotic pressure of the external 'milieu'" . Journal of Comparative Physiology B, vol. 154, no. 6, 1984, pp. 573-578.
http://dx.doi.org/10.1007/BF00684410
---------- VANCOUVER ----------
Segura, E.T., Reboreda, J.C., Skorka, A., Cuello, M.E., Petriella, S. Role of the CNS in the control of the water economy of the toad Bufo arenarum Hensel - III. Skin permeability increases to raised osmotic pressure of the external 'milieu'. J Comp Physiol B. 1984;154(6):573-578.
http://dx.doi.org/10.1007/BF00684410