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S E Dicker

Publications and source records attributed to S E Dicker.

52 records · Page 3Linked to original sources
PubMed1967

Water uptake by Bufo melanostictus, as affected by osmotic gradients, vasopressin and temperature.

1. The rate of water uptake across the skin was studied in the live toad, Bufo melanostictus. When toads were kept in distilled water at 29 degrees C the uptake of water amounted to 16.9 +/- 1.3 mul./cm(2)/hr; when bathed in sucrose or urea solutions, the water uptake diminished with increasing osmotic pressure. There was no water uptake observed when toads were kept in 200 m-osmolar sucrose or urea.2. Intramuscular injections of vasopressin increased the rate of water uptake from distilled water. There was a good relation between doses and responses over various time intervals. A dose of 4 m-u. vasopressin/g body wt. doubled the rate of water uptake over a period of 1 hr. The same dose of vasopressin doubled the rate of water uptake when the toads were kept in solutions of sucrose or urea of different osmolarity.3. The rate of water uptake when the toads were bathed in sodium chloride solutions was consistently 8 mul./cm(2)/hr greater than when bathed in sucrose or urea solutions of equal osmolarity. There was no water uptake when the sodium chloride solution was 285 m-osmolar.4. Vasopressin (4 m-u./g) injected intramuscularly doubled the rate of water uptake from sodium chloride solutions of different osmolarity.5. With solutions of potassium chloride, sodium nitrate, and potassium nitrate, in concentrations up to 150 m-osmoles/l., the rate of water uptake was found to be the same as with solutions of sodium chloride of the same osmolarity. Similarly, it was doubled by injection of vasopressin (4m-u./g).6. The effect of temperature on the rate of water uptake before and after injection of vasopressin was investigated in toads kept in distilled water, sucrose, or sodium chloride solutions. For temperatures between 20 and 37 degrees C, vasopressin (4 m-u./g) reduced the activation energy involved in the process of water uptake by 4000 cal.7. The results agree with the view that water uptake follows a diffusion process which is facilitated by vasopressin, possibly as a result of increasing the size or number of available pores.

Animals↗
PubMed1966

Water diuresis in the domestic fowl.

1. The exteriorization of ureters in domestic fowls allows the collection of urine uncontaminated by faeces.2. When water is administered by stomach tube to a fowl, water is stored in the crop, from which it is slowly released into the proventriculus.3. Immediately after water gavage, there is a sharp rise of urine flow accompanied by an increase in endogenous creatinine excretion and a fall in the osmolarity of the urine. This initial increase in urine flow is of short duration, and is followed by a normal curve of diuresis with a peak at about 90 min after hydration.4. The first rise in urine flow following the filling of the crop appears to be of reflex origin, as distension of the crop with paraffin produces an enhanced excretion of urine and of creatinine.5. Changes in urine flow and in creatinine excretion are closely correlated.6. After water deprivation for 18 hr, the urine is slightly hyptertonic to blood. The maximum urine concentration observed was of the order of 600 m-osmole/l.

Animals↗
PubMed1966

Release of vasopressin and oxytocin from isolated pituitary glands of adult and new-born rats.

1. Pituitary glands of adult rats of both sexes, of lactating female and of new-born rats, incubated in a Locke solution, release both oxytocin and vasopressin. The amount of hormones released, during a measured period of incubation, is related to the actual hormone content of the gland.2. Increasing the concentration of KCl in the incubation medium, with CaCl(2) present and in concentration of at least 2.2 mM, produces an enhanced release of both hormones from pituitary glands of adults, but does not affect the release of hormones from glands of new-born animals.3. Addition of ouabain to the incubation medium produces a marked increase of the release of the hormones from glands of both adult and new-born rats. This is accompanied by an extrusion of K ion and an influx of Na ion. The effect of ouabain on the hormone release and the shift of ions can be reversed by subsequent addition of adenosine triphosphate.4. The increased release of hormones produced by ouabain, in glands from new-born rats, is unaffected by the presence or absence of CaCl(2). In adults, however, the effect of ouabain, though present, is reduced in the absence of CaCl(2).5. It is suggested that in glands from adult animals, the hormones must be freed from their attachment on the protein-carrier, neurophysin and that this can be achieved by the entry of calcium ion into the cell. The subsequent secretion of the ;freed' hormones appears to be accompanied by a shift of ions across the cell membrane.6. In glands from neonates up to 3 weeks old, the absence of neurophysin, or its poor capacity for binding the hormones, explains the inability of calcium to operate in the same way as in the glands of adults. There is evidence suggesting that the secretion of the neurohypophysial hormones in the new-born animal consists mainly of their diffusion from the cells, without previous elution of the hormones as in adults.

Journal Article↗
PubMed1966

The isolation of hyaluronic acid and chondroitin sulphate from kidneys and their reaction with urinary hyaluronidase.

1. Extracts of the cortex and the medulla of fresh kidneys from pigs, sheep and dogs were analysed for the presence of acid mucopolysaccharides.2. Acid mucopolysaccharides were found in the kidneys of the three species and were evenly distributed between cortex and medulla.3. The acid mucopolysaccharides isolated from either the medulla or the cortex of kidneys contained equal amounts of sulphated and nonsulphated fractions; these could be identified as chondroitin sulphate and hyaluronic acid, respectively.4. Urinary hyaluronidase was isolated from urine and estimated by means of turbidity measurements.5. Urine hyaluronidase depolymerizes the acid mucopolysaccharides extracted from either the cortex or the medulla of the kidneys from pig, sheep and dog.6. The enzymic activity of urine hyaluronidase could be expressed as units/mg of protein. The optimum pH activity of the enzyme is at about 4.0.

Animals↗
PubMed1966

The effects of urea and hydrochlorothiazide on the renal functions of rat and domestic fowl.

1. Rats and domestic fowls were given by stomach tube water, urea and hydrochlorothiazide, alone or in combination, in the following amounts: water, 5 ml./100 g; urea, 4 ml. of 1.5% solution + 1 ml. water/100 g; hydrochlorothiazide, 4 ml. of 1.5% urea solution + 1 ml. containing 0.1 mg hydrochlorothiazide/100 g.2. The onset of water diuresis was faster in the fowl than in the rat. It was accompanied by a lower rate of excretion of osmotically active solutes in the former than in the latter. The rate of excretion of creatinine in rats was fourfold that in birds.3. After urea administration, the amount of urea excreted by the fowl was about one fifth that excreted by the rats. While urea produced in rats an osmotic diuresis, with enhanced excretion of osmotically active solutes, in birds it had little effect on either urine flow or solutes excretion.4. Administration of hydrochlorothiazide in rats produced a moderate antidiuresis accompanied by a marked increased excretion of Na and K; in birds, a small increase in the excretion of Na and K but no effect on the urine flow.5. The differences observed between rats and birds can be attributed to the poor development of filtration rate and the absence of a well developed counter-current system in the fowl.

Animals↗