Osmotic Factors Research Articles

Prolactin and Osmoregulation

The actions of prolactin in hydromineral metabolism in all vertebrate classes are reviewed, and the impact of the studies on nonmammalian vertebrates in providing impetus for comparable research in mammals is emphasized. The teleost bladder is a model system for analyzing the interaction of prolactin and cortisol in transport processes; a parallelism is suggested between this model and the prolactin/cortisol regulation of ion and water movements during milk secretion. The immediate osmoregulatory effects claimed for prolacti in vitro are questioned; however, under organ-culture conditions the action of the hormone is readily demonstrable. Progress in the isolation of teleost prolactin and the role of osmotic factors in regulating prolactin secretion are briefly described.

Die Proteinverteilung im postischämischen Ödem des Hundes als Hinweis zur Ödemgenese*

A postischemic edema in hind limbs of dogs occurred after a 5 hours tourniquet ischemia. The protein distribution of edematous liquid, serum and lymph has been investigated by immunoelectrophoretic analysis. Using different identification reactions it could be demonstrated, that edematous liquid only differs from serum because of additional appearance of fibrinogen, so corresponding qualitatively and in so far estimated quantitatively to serum plasma. In connection with the osmotic pressure factors and postischemic hyperemia, as they have been demonstrated up to now, the severe changes of permeability seem to be a main factor in pathogenesis of postischemic edemas.

A method for studying reactions to microorganisms added to the soft cuticle of aquatic arthropods

Superficial wounding of crayfish soft cuticle by removal of the epicuticle caused hemocyte aggregation beneath the wound. The aggregation seemed to be induced by osmotic factors. Subsequently, melanin was only formed in parts of the wound region. Swimming zoospores of the fungal parasite Aphanomyces astaci preferentially encysted in the near vicinity of fresh superficial wounds. Cysts attached onto the naked endocuticle became encapsulated by melanin and were mostly killed during the process. The induced melanization reactions may have antifungal effects. The intermolt cuticle of a highly resistant crayfish species, Pacifastacus leniusculus, was easily penetrated by the fungus only via wounds. The cell walls of the penetrating hyphae became heavily melanized, growth was visibly disturbed, and they grew sparsely in the wound region. As soon as they reached outside the wound region they grew profusely. In susceptible crayfish Astacus astacus melanization was slower and the wound reactions prevented fungal growth much less as evidenced by microscopy. The preferential direction of hyphal growth is parallel to the chitin fibrils in both the resistant crayfish P. leniusculus and the susceptible A. astacus.

Oviposition and development of two intertidal snails, Littorina sitkana and Littorina scutulata

At San Juan Island, Littorina scutulata spawns in the summer, releasing pelagic egg capsules with planktotrophic development, whereas Littorina sitkana spawns in the spring and autumn and lays benthic egg masses with lecithotrophic development. The larval development of each species is described and the chronological events from fertilization to hatching are tabulated.L. scutulata veligers hatch by a combination of mechanical and osmotic factors but L. sitkana juveniles utilize the foot and shell to rupture the capsular wall and capsular membrane. It was postulated that rows of tubercles on the larval shell of L. sitkana form an abrasive surface which facilitates hatching.Embryonic and juvenile growth was studied in L. sitkana. A rapid growth phase is observed when the young veliger begins to feed on the albumen.

Osmotic factors of hardiness in flowering dogwood

Osmotic factors of hardiness in flowering dogwood

Conjoint action of sodium and angiotensin on brain mechanisms controlling water and salt balances.

AbstractAndersson, B. and L. Eriksson, Conjoint action of sodium and angiotensin on brain mechanisms controlling water and salt balances. Acta physiol. scand. 1971. 81. 18–29.The effects on water and salt balances of a simultaneous infusion of angiotensin and hypertonic NaCl into the 3rd brain ventricle were studied in goats in normal water balance and in hydrated animals. For comparison similar infusions of angiotensin alone (solved in slightly hypotonic saline) and of hypertonic NaCl were made. Like the hypertonic NaCl, 30 min infusions of angiotensin alone induced drinking in animals in normal water balance, and an inhibition of the water diuresis in the hydrated goat. The simultaneous infusion of both substances resulted in a marked potentiation of the dipsogenic and the antidiuretic effects. A possible explanation may be that angiotensin facilitates the transport of Na+ into brain cells regulating thirst and ADH release, and that the intracellular Na+ concentration rather than strictly osmotic factors determines the activity of these cells. In the hydrated goat a central effect of angiotensin strongly enhanced the natriuretic response to intraventricular infusions of hypertonic NaCl, and extreme natriuresis developed as result of the combined infusions in hydrated, salt‐supplemented animals. During normal water balance this sodium‐angiotensin synergism was less obvious, which suggests that both an expanded fluid volume and an elevated intracellular Na+ concentration are needed for optimal activation of a brain mechanism which stimulates renal Na' excretion, The time course of the centrally induced natriuresis indicates that the effect on the kidney may be mediated by a humoral agent.

Synergistic action of sodium and angiotensin on brain mechanisms controlling fluid balance

The effects on water and salt turnover of the simultaneous infusion of angiotensin and hypertonic NaCl into the 3rd brain ventricle were studied in goats in normal water balance and in hydrated animals. Angiotensin strongly potentiated the dipsogenic and antidiuretic effects of hypertonic saline. A possible explanation may be that angiotensin facilitates the transport of Na + into brain cells involved in the regulation of thirst and ADH release, and that the intracellular Na + concentration (rather than strictly osmotic factors) may determine the activity of these neurons. In the hydrated goat a central effect of angiotensin also enhanced the natriuretic response to intraventricular infusions of hypertonic NaCl, suggesting that both an expanded fluid volume and an elevated intracellular Na + concentration may be needed to obtain optimal activation of a brain mechanism which stimulates renal sodium excretion.

Osmotic factors determining the release of catecholamines from isolated chromaffin cell granules.

AbstractLishajko, F. Osmotic factors determining the releme of catecholamines from isolated chromaffin cell granules. Acta physiol. scand. 1970. 79. 64–75.On incubation of bovine adrenal medullary granules in isotonic sucrose, KCl, NaCl or K‐phosphate, noradrenaline (NA) is initially released at a rapid rate followed by a slow exponential release. Adrenaline (A) release in the same media does not show the rapid initial phase. In hypotonic media both NA and A show a rapid initial release while in hyper‐tonic solutions both NA and A are released at a constant slow rate (t/2 = 115–185 min at 37°). Partial replacement of sucrose or dextrose media by NaCI, KCl or K‐phosphate decreases the release rate of Na and A. Addition of 6 mM Mg2+ or Ca2+ prevents the initial rapid fall of NA and of A in hypotonic solution. ATP‐Mg2+ inhibits the release rate of catecholamines in chloride free media more than ATP or Mg2+ alone. The granules were shown to shrink in the presence of divalent ions, as well as on addition of ATP or ATP‐Mg2+. During partial lysis or “osmotic shock” the granules lose slightly more A than NA. The results suggest that the NA containing granules from chromaffin cells initially possess a higher osmotic pressure than that of the A granules, possibly depending on the rate of splitting of an amine‐ATP‐complex. The release may depend partly on the ensuing osmotic equilibration process.

Ion transport by heart mitochondria. XV. Morphological changes associated with the penetration of solutes into isolated heart mitochondria

1. The morphology of isolated beef heart mitochondria has been compared with the water content, cation content, and mannitol-permeable water volume. Mitochondria suspended in isotonic potassium acetate take up K + and acetate spontaneously by an energy-linked reaction. The ion uptake is accompanied by extensive swelling of the mannitol (or sucrose)-impermeable water volume and by a dilation of the matrix space in electron micrographs. A similar ion uptake, increase in mannitol-impermeable water, and dilation of the matrix is seen in isotonic potassium acetate in the absence of energy when the membrane is made permeable to K + by the addition of gramicidin. 2. Expansion of the matrix and increases in the mannitol-impermeable water volume similar to those noted above for osmotic swelling in potassium acetate also occur when mitochondria are suspended in hypotonic solutions of sucrose or KCl. 3. In isotonic KCl the impermeant Cl − prevents the accumulation of K + either by the energy-linked reaction or by the passive, gramicidin-induced reaction. The uptake of K +, increases in mannitol-impermeable water, and dilation of the matrix do not occur in this medium in the presence of a source of energy or in the absence of energy when gramicidin is added. Dilation of the matrix can be seen in isotonic KCl only when the membrane is made permeable to Cl − by either the addition of p-hydroxymercuribenzoate or by the combination of gramicidin and metabolic energy. 4. It can be concluded that the matrix space in electron micrographs correlates well with the mannitol-impermeable water volume which is observed in isotope experiments. It can also be concluded that the morphological changes reported here are closely related to osmotic factors.

Thirst and artificial heat acclimatization in man

The purpose of this study was to investigate the relationship between serum osmotic changes, water intake and water balance in four, fit young men during and after exercise in the heat, before and after artificial heat acclimatization. During exercise, before steady-state conditions were reached, voluntary water intakes generally paralleled but were not proportional to the serum osmotic pressure. In steady-state conditions, drinking was approximately proportional to the effective osmotic pressure of the serum. During the post-exercise recovery period, when serum osmolarity returned to normal levels, water intake also subsided even though there was a total body water (wt) deficit of about 3%. Body weight did not return to control levels until 62 to 86 hr following the exercise. This slow recovery could not be accounted for by a loss of water associated with glycogen utilization during exercise or by sweat electrolyte depletion. In general, the results supported Dill's hypothesis but plasma volume changes, in addition to osmotic factors,are very likely operative in the initiation and satiation of drinking under these conditions. Perhaps slower acting volume control mechanisms mediate the slow recovery of total body water.

A model for renal-electrolyte regulation

The present report provides a detailed systems analysis of the kidney and the associated electrolyte regulatory mechanism, which will be referred to, for purposes of brevity, as the renal chemostat. The model explicitly incorporates the effect of water and salt intake, pulmonary CO 2 tension, as well as the main features of renal physiology as it is presently understood. Thus the regulatory function of both aldosterone and antidiuretic hormone are included as well as the effect of such parameters as pH, salt concentration, plasma volume and osmotic factors. The present work thus provides a basis for the development of an electronic analog of the renal-electrolyte system.

Taste-Discrimination in the Monkey

Taste-discrimination in animals has been investigated traditionally by the use of some variant of the 'preference method' in which the discrimination is evidenced by the relative amount of a fluid that is consumed in a free-choice situation. The limitations of this procedure as a way of determining taste-sensitivity are, by now, well organized.1 It confounds the discriminative function of the taste-stimuli with a reinforcing function, since the reinforcement is obtained directly from the solutions to be discriminated. Consequently, it becomes uncertain whether a failure to discriminate relates to factors of taste-sensitivity or to the reinforcing role of the stimuli, or both. Moreover, under conditions which involve the consumption of appreciable amounts of hypertonic fluids, taste and preference become further confounded with post-ingestional osmotic factors as determinants of the discriminative behavior.2

Moderate level x-ray effect on active transport mechanism in dog intestine.

SummaryEarlier reports of this group have described the basic model for analysis of tracer data in the Thiry-Vella preparation using 24Na and 3H as tracers. At that time, it was reported also that the lumen-to-plasma transfer rate of sodium was increased on the third day following 600 r whole-body irradiation (1 MVP). It has since also been possible to demonstrate (1) the active transport of water and (2) increases in the magnitude of active water transport on the second to third day. Active water transport is normally about 20 per cent of the total unidirectional efflux. After irradiation, active water transport is significantly increased by a factor of 1·7. In accordance with a more recent fluid circuit theory of ion accumulation, the increase in active water transport is observed to be accompanied by the increase in sodium efflux. While diffusional and osmotic factors are still operative, conclusions about active water transport were deduced from independent manipulations of osmotic and diffusional dif...

The Behaviour of sterilised exsheathed infective Trichostrongylid larvae in sterile media resembling their environment in Ovine hosts

1. Attempts were made to cultivate in sterile artificial media the sterilised first parasitic larva of intestinal nematodes of sheep. These larvae were obtained by artificial production of the second ecdysis in 1 in 20 dilutions of Milton hypochlorite in distilled water.2. Over 1,500 larvae were thus isolated, usually in hanging drops, in more than 200 different sterile media, containing ingredients likely to be present in the normal environment of these larvae inside their hosts.3. None of the larvae showed any growth. Most formed the next sheath and were ready for the third ecdysis, but only 10 larvae actually performed this. The parasitic third larva thus liberated always emerged by a rent at the side of the eosophageal region of the sheath, and never by detachment of a cap like that characteristic of the second ecdysis. In every instance the parasitic third larva died immediately after the third ecdysis, which set it free. Two of these 10 larvae underwent the second and third ecdyses simultaneously.4. The methods used by the writer (1933b) to induce artificially the second ecdysis always failed to produce the third ecdysis. No method of producing this at will was found.5. The longest time any first parasitic larva lived was 41 days. Few of them lived, however, less than 8–10 days. A life of 18–30 days was more usual before visible signs of physiological abnormality appeared, such as the gradual vacuolation and emptying of the intestinal cells which usually preceded their death.6. Those which were ready with a loose sheath for the third ecdysis, showed, as infective larvae also do, remarkable powers of resistance to changes produced in them by osmotic factors.7. None of the larvae showed any particular reaction to blood, mucosa of the stomach or duodenum, nor, indeed, to any of the ferments or tissues these larvae encounter in their hosts. They seemed to be as indifferent in this respect as the sheathed infective larvae are.8. A comparative physiological study of the sheathed infective and the exsheathed first parasitic phases of the second larva would verify, and perhaps modify, our knowledge of the functions of the so-called protective sheath of the infective larva.