Natriferic and hydrosmotic effects of neurohypophysial peptides and their analogues in augmenting fluid uptake by <i>Bufo melanostictus</i>

Elliott, Annie B.

doi:10.1113/jphysiol.1968.sp008553

Cited by 6 publications

(1 citation statement)

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“…Neurohypophysial hormones exert a hydrosmotic effect, increasing the water permeability of amphibian skin and urinary bladder to a degree which varies in accordance with the species (Bentley, 1966) and with the chemical nature of the peptide (Schwartz & Livingston, 1964;Dicker & Elliott, 1970b). Similarly, the natriferic action, increasing the rate of sodium transport, varies with the species and the peptide (Jard, Maetz & Morel, 1960;Elliott, 1968). Both hydrosmotic and natriferic actions have been thought to contribute to the total control of water balance in freshwater amphibians (Heller, 1965).…”

Section: Introductionmentioning

confidence: 99%

Permeability of urinary bladder of Rana cancrivora to urea in the presence of oxytocin

Chew¹,

Elliott²,

Wong³

1972

The Journal of Physiology

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SUMMARY1. When Rana cancrivora collected from fresh water had been exposed for 3 days to saline solutions having osmolalities from 280 to 690 m-osmole/ kg, urea concentrations in plasma and urine appeared to come into equilibrium, and were from 70 to 200 m-mole/l.2. Plasma urea level of fresh water R. cancrivora (48 m-mole/l.) was doubled (82 m-mole/l.) after 8 hr of exposure to 270 m-osmolal saline. It continued the same after 24 hr of exposure.3. When isolated urinary bladders of R. cancrivora were exposed to Ringer on the serosal aspect and one-fifth Ringer on the mucosal aspect, then in response to this osmotic difference of 190 m-osmole/kg, the rate of fluid movement (mucosa to serosa), which was 10-3(±2)#l./cm2.hr, was not significantly altered when up to 60 % of the NaCl of the Ringer solution was substituted by urea.4. Under the same circumstances, when oxytocin (50 m-u./ml.) was present in the serosal solution, the rate of fluid movement (mucosa to serosa) was 133.2( ± 7.9) tl./cm2.hr in the absence of urea; it was progressively decreased by the presence of urea until, when 80 % of the NaCl had been substituted by urea, the rate of fluid movement was reduced to 14.5( ± 4.0) ,ul./cm2.hr.5. The diminished rate of fluid movement under the above circumstances could not be correlated with serosal urea concentration, with serosal availability of Na+, nor with Na+ concentration difference across the bladder wall. It appeared to be directly related to the 'non-urea osmotic difference' across the bladder wall provided by solutes other than urea.6. When isolated bladders were exposed to an osmotic difference of 190 m-osmole/kg, but having 25 mm urea present in the mucosal solution, then fluid moved from mucosa to serosa at a rate of 10.4( ± 1-3) ttl./cm2 . hr in the absence of oxytocin and 124( ± 9) Il./cm2 . hr when oxytocin (50 m-u./ 758 M.-M. CHEW, A. B. ELLIOTT AND H. Y. WONG ml.) was present. In the former case no urea passed across the bladder wall, but in the latter case urea passed from mucosa to serosa at a rate of 3-16( ± 0.3) /tmole/cm2.hr. The fluid moving from mucosa to serosa thus contained urea 25-5 m-mole/l.7. Vasotocin (10-9 M), which is equipotent with oxytocin (50 m-u./ml.) in affecting permeability of the isolated urinary bladder to water, was also equipotent in producing a reduced rate of water fluid movement in the presence of 40 % urea (vasotocin, 63 /u1./cm2.br; oxytocin, 59 p1./cm2.br). 9. The hypothesis is presented that hormone-induced permeability of the urinary bladder to urea contributes to the immediate adjustment of plasma urea level by which R. cancrivora survives when exposed to high environmental salinity.

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Section: Introductionmentioning

confidence: 99%