Temporary peritoneal sequestration of NaCl and persistent NaCl appetite.
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Slightly halophilic marine Vibrio alginolyticus grown in the range of NaCl from 0.2 to 1.5 M maintained the total internal solute concentration always higher than the external medium by about 0.25 osM. The concentrations of macromolecules such as DNA, RNA, and protein were little affected by the increase in medium NaCl. The internal K+ concentration was kept to about 400 mM in the range of medium NaCl from 0.4 to 0.8 M; it rose to 510 mM when the bacterium was grown in 1.5 M NaCl, indicating that K+ increased only slightly in response to the large increase in medium NaCl. Thus, in contrast to the case of nonhalophilic and extremely halophilic bacteria, K+ was unlikely to act as a major component to regulate the internal solute concentration of marine V. alginolyticus. The internal Na+ and Cl- concentrations were maintained always lower than those in the growth medium, but they increased in response to the increase in medium NaCl. The concentration of internal Na+ was close to that of K+ at the concentration of medium NaCl that supports the optimal growth of this organism. The total amino acid content of V. alginolyticus increased from 76 to 413 mM by the increase in medium NaCl from 0.2 to 1.5 M. The concentrations of glutamic acid and prolined were 254 and 72 mM, respectively, when grown in 1.5 M NaCl. These results indicated that Na+, Cl- and amino acids, especially glutamic acid and proline, contributed to the regulation of internal solute concentration of V. alginolyticus in response to the increased external NaCl.
The interrelationship of blood pressure, cardiac output, and peripheral resistance was studied in Dahl "S" and "R" rats after 3 days on a high (8%) NaCl diet. Both "S" and "R" rats were normotensive when fed a normal (0.3%) NaCl diet. After 3 days of the high NaCl diet, the "R" rats remained normotensive (BP 112 mm Hg), while the "S" rats had an elevation of arterial pressure (BP 133 mm Hg) (p less than 0.001). The cardiac outputs of both "S" and "R" rats were similar on the low NaCl diet. After 3 days of high NaCl feeding, the cardiac output of the "R" rats rose 18% above the "R" control level (p less than 0.0001), while the peripheral resistance declined 14% below the "R" control level (p less than 0.005), and the blood pressure (BP) did not change, a pattern quite contrary to the concept of "whole-body" autoregulation. With a similar 3-day high NaCl feeding in "S" rats, cardiac output (p less than 0.005) and peripheral resistance (p less than 0.05) both increased 10%, while BP rose 20%. After 7 days of high NaCl feeding, the cardiac output of the "S" rats had returned to normal, while blood pressure and peripheral resistance both continued to be elevated. This pattern of response in "S" rats could be compatible with the concept of "whole-body" autoregulation. However, since both NaCl hypertension and Goldblatt hypertension can occur in settings in which "whole-body" autoregulation appears not be to causally related, one cannot be certain whether "whole-body" autoregulation is playing a causal role in the mechanism of NaCl-induced hypertension in "S" rats. It is a striking dichotomy that 3 days of high salt feeding produces vasoconstriction in "S" rats and vasodilation in "R" rats.
The solubilisation of Epstein-Barr virus (EBV)-associated nuclear antigen (EBNA) by treatment with various molarities of NaCl was investigated using the 125I--IgG absorption assay. Ninety percent of the antigenic activity detected using the 125I--IgG absorption assay was insoluble at 0.15 M NaCl. It could be rendered soluble by treatment with 2.0 M NaCl, but reprecipitated upon return to 0.15 M NaCl. EBNA was partially extracted from Raji chromatin by treatment with 0.35 M NaCl. The efficiency of extraction was increased by homogenisation in 2.0 M NaCl followed by dialysis to 0.35 M NaCl. The data demonstrate the close association of EBNA with Raji chromatin and suggest that it may be a chromatin-associated non-histone protein.
The effects of a wide concentration range of NaCl solutions containing either ouabain, ethanol, para-nitroacetophenone (PNAP), N-ethylmaleimide (NEM), cysteamine or dimethyl sulphoxide (DMSO) on cellular radiosensitivity have been examined. Ouabain and NEM treatment increased the radiosensitivity of V79 Chinese hamster cells, but the action of these chemicals did not depend on the concentration of NaCl. PNAP increased cellular radiosensitivity with increasing NaCl concentration reaching a maximum effect at 0.6 to 0.7 M NaCl. The radioprotective properties of cysteamine, DMSO and ethanol were all strongly dependent on the NaCl concentration in a complex but qualitatively similar manner. DMSO (2.0 M) increased radiation survival of cells after a 1380 rad dose by a factor of about 10(4) when present in 0.075 M NaCl and by a factor of 8.7 when present in 1.2 M NaCl.
1. Two distinct patterns of tryptic modification of the catalytic functions of purified (Na+ + K+)-ATPase can be related to the two previously described patterns of enzyme inactivation and cleavage of the large chain seen with NaCl and KCl (Jorgensen, P.L. (1975) Biochim. Biophys. Acta 401, 399-415). 2. With NaCl, in phase A, the rapid inactivation of 50-55% of the (Na+ + K+)-ATPase activity is associated with loss of 85% of the K+-phosphatase activity and an increase in Na+-ADP-ATP exchange activity to 150% of control. ATP binding and phosphorylation are unchanged and the inactivation may result from cleavage of bonds within the large chain which are involved in dephosphorylation reactions. In phase B with NaCl, ATP binding and phosphorylation are lost slowly in parallel to inactivation of (Na+ + K+)-ATPase and cleavage of the large chain to a fragment with Mr=78 000. 3. With KCl, cleavage of the large chain to almost equal fragments abolish ATP binding and phosphorylation in parallel to the inactivation of (Na+ + K+)-ATPase. An additional split seems required for inactivation of the K+-pNPPase activity. 4. After completion of the digestion in phase A with NaCl a stable preparation can be isolated in which the activity of (Na+ + K+)-ATPase is 40%. ATP binding and phosphorylation are 90%, K+-phosphatase is 15%, and Na+-ADP-ATP exchange is 150% of control. We currently examine if these levels are related to changes in phosphorylation kinetics. 5. The ATP binding area is much more stable to trypsin with NaCl than with KCl, but loss of the binding capacity is in both cases correlated to a distinct cleavage of the large chain. The relationship between the fractional loss of ATP binding and cleavage of the large chain suggests that the nucleotide binding area is confined to one of the two large chains in the protein complex with Mr=270 000 which binds one molecule of ATP. 6. The data also suggest that the phosphatase site is remote from the ATP binding area. It is proposed that the protein complex with Mr=270 000 contains two large chains with different catalytic functions and that each chain forms a cation channel.
Adaptation of Ehrlich ascites tumor cells to serial cultivation in media with progressively elevated (hypertonic) NaCl content ("high NaCl"-tolerant cells) has resulted in progressive increases of the cellular activities of NAD-dependent glycerol-3-phosphate dehydrogenase (EC 1.1.1.8), NAD-dependent malate dehydrogenase (EC 1.1.1.37), glutamate--oxalacetate transaminase (EC 2.6.1.1), NAD (P)-dependent glutamate dehydrogenase (EC 1.4.1.3), NADP-dependent isocitrate dehydrogenase (EC 1.1.1.42). The activities of glutamate-pyruvate transaminase (EC 2.6.1.2.) and of glycolytic enzymes as phospho-fructokinase (EC 2.7.1.11), glyceraldehydephosphate dehydrogenase (EC 1.2.1.12) and lactate dehydrogenase (EC 1.1.1.27) were only slightly and not in progressive manner (in response to the progressive increase of the environmental NaCl concentration) affected. These changes are discussed with respect to a metabolic pattern of these "high NaCl"-tolerant cells which is compatible with increased energy requirements, especially for active cation transport. It is suggested that these increased cellular enzyme activities reflect an increased transfer of reducing equivalents across mitochondrial membranes (via the "glycerophosphate cycle and the malate-aspartate shuttle") and possibly a stimulated lipid metabolism. These alterations in the level of enzyme activities must be regarded asan adaptive cellular response to the "high NaCl" environment, since readaptation to growth in regular isotonic media resulted in a reversion to the enzyme pattern characteristic of the parent cells.
Dahl 'S' rats become hypertensive when fed a high NaCl diet but remain normotensive on a low NaCl diet. Dahl 'R' rats are normotensive on either diet. For a given perfusion pressure, isolated 'S' kidneys excrete 50% less Na than 'R' kidneys. Therefore, we searched for a Na-retaining hormone in 'S' rats. Kidneys were isolated without ischemia from normal rats and were continuously perfused at 125 mm Hg with blood from Dahl 'S' and 'R' rats, all on low NaCl diets. Kidneys and adrenals had been extirpated from the perfusing rats. During 15 min of perfusion, the isolated 'normal' kidneys excreted a mean of 164 micronEq of Na/min/100 g during 26 perfusion experiments with blood from 'R' rats. The 'normal' kidneys excreted a mean of 84 micronEq Na during 24 perfusions with blood from 'S' rats. Thus, the normal kidneys excreted half as much Na when perfused with 'S' blood compared with 'R' blood (p less than 0.02). Seemingly, a Na-retaining humoral agent is present in the blood of 'S' rats on a low Na diet in the absence of renal and adrenal tissue. Moreover, in these normal kidneys, perfusion with 'S' blood induced a 16% higher renal vascular resistance than perfusion with 'R' blood (p less than 0.01), indicating vasoconstricting agents in 'S' blood. However, the Na-retaining humoral effect in 'S' blood could lead to Na retention by 'S' kidneys in vivo, which could partially account for the susceptibility of 'S' rats to NaCl hypertension. Hypertension in Dahl 'S' rats can be almost completely prevented by concomitant treatment with thiazide diuretics which act mainly on the kidney to facilitate Na excretion. This result is in agreement with the hypothesis that a shift in the pressure natriuresis curve, reducing Na excretion for a given arterial pressure, is partially responsible for the great sensitivity to NaCl hypertension in the 'S' rat. The Na-retaining hormone may contribute to this shift.
The colon and coprodeum of anaesthetised laying hens was perfused luminally with solutions of varying compositions, to elucidate the influence of three levels of dietary NaCl and of luminal NaCl concentrations on coprodeal and colonic transport of NaCl. Net Na+ and Cl- absorption rates were increased in response to low dietary Na+ levels and higher luminal NaCl concentrations. Net Na+ absorption was always against the prevailing electrochemical gradient, saturably dependent on luminal Na+ concentrations in low Na+ diet birds, and linearly dependent on luminal concentrations in medium and high Na+ diet birds. Net Cl- absorption was usually down its electrochemical gradient. The Cl- flux rates were strongly linearly dependent on Na+ flux rates, and statistically this relationship could account for all significant variation of Cl- fluxes associated with dietary and perfusate treatments. Transmural electrical potential differences were invariably serosa positive, and partly correlated with Na+ fluxes.
The results of the present study that NaCl transport by in vitro rabbit gallbladder must be a consequence of a neutral coupled carrier-mediated mechanism that ultimately results in the active absorption of both ions; pure electrical coupling between the movements of Na and Cl can be excluded on the grounds of electrphysiologic considerations. Studies on the unidirectional influxes of Na and Cl have localized the site of this coupled mechanism to the mucosal membranes. Studies on the intracellular ion concentrations and the intracellular electrical potential are consistent with the notion that (a) the coupled NaCl influx process results in the movement of Cl from the mucosal solution into the cell against an apparent electrochemical potential difference; (b) the energy for the uphill movement of Cl is derived from the Na gradient across the mucosal membrane which is maintained by an active Na extrusion mechanism located at the basolateral membranes; and (c) Cl exit from the cell across the basolateral membranes is directed down an electrochemical potential gradient and may be diffusional. Finally, as for the case of rabbit ileum, the coupled NaCl influx process is inhibited by elevated intracellular levels of cyclic 3',5'-adenosine monophosphate. A working model for transcellular and paracellular NaCl transport by in vitro rabbit gallbladder is proposed.
Prepubescent male and female rats (N = 56) were surgically thyroidectomized and given stomach loads of .9% or 6.0% NaCl. The 6.0% NaCl, thyroidectomized S s responded by decreasing food intake and losing weight 24 hours after loading. Normal S s did not, and no sex difference was found. The .9% NaCl thyroidectomized S s drank significantly less than the normals. The results were interpreted in terms of thyroid hormone activity which affects renal function.
The effects of phenylalanine, NaCl and pH on the conformation of chorismate mutase/prephenate dehydratase have been investigated, using measurements of far and near-ultraviolet circular dichroic spectra and ultraviolet difference spectra. At pH 8.2 in 20 mM Tris-Cl buffer the enzyme was found to contain 10-20% helix and 40-50% beta-structure. There was little or no change in these values on the addition of 1 mM phenylalanine (the allosteric effector) or 0.4 M NaCl or by decreasing the pH to 7.4. Both phenylalanine and NaCl caused significant changes in the conformation of the enzyme. The most prominent of these was the movement of a tryptophan residue into a more hydrophobic environment. There was also a slight perturbation of this tryptophan when the pH was decreased to 7.4. The conformational changes can explain sigmoidal kinetic behaviour observed previously [Gething et al. (1976) Eur. J. Biochem. 71, 317-325].
The rates of fluid and NaCl absorption are greater in the proximal than in the distal colon. Prolactin treatment caused significant increases in fluid and NaCl absorption in the proximal but not in the distal colon. This suggests that only the proximal colon region, where most of the fluid and sodium absorption takes place, is responsive to prolactin.
Multiple-unit recordings were taken from the lateral preoptic region during a series of hypertonic and isotonic NaCl and sucrose intracarotid injections. Subjects were 11 hooded rats (8 males and 3 ovariectomized females) under urethane anesthesia. The data showed that under favorable cannulation conditions there were strong multiple-unit responses to hypertonic sucrose injections, and that under these conditions NaCl injections were not significantly more effective than sucrose injections. The possible bearing of these findings on hypotheses concerning central receptors for thirst is discussed.
Rats received an ad lib choice of food, water, and a solution containing saccharin, glucose, and NaCl solutes either as single stimuli or in combinations. Ethanol was gradually added to these vehicles or water from 0.5--15% w/v. Ethanol intakes of all groups with vehicles containing glucose were higher than intakes of the water vehicle group. Ethanol intakes of the 0.125% saccharin + 3.0% glucose + 1.0% NaCl + ethanol group were highest, peaking at greater than 9.0 g/kg/day, and this group displayed the highest blood ethanol levels. However, there was no evidence of withdrawal syndrome, nor of increased intake of unflavored ethanol by groups previously receiving flavored ethanol. It is suggested that ethanol eliminative capacity limits free-choice ethanol intake when maximized by the addition of sapid congeners.
Plasma renin activities (PRA) and aldosterone concentrations increased in parallel over a wide range of plasma volume deficits produced in unanesthetized rats by extravascular administration of polyethylene glycol (PEG) solution. When PEG-treated rats were given water to drink, their intakes were proportional to PRA; when given water and 0.5 M NaCl, PRA and the steroid concentrations diminished concurrently in association with sodium consumption. Aldosterone concentrations and NaCl intakes were markedly enhanced after PEG treatment in rats maintained on a sodium-deficient diet for 4 days. On the other hand, a clear relation between PRA and water intake, and between circulating aldosterone levels and sodium intake, was not suggested by other experiments in this series. For example, bilateral nephrectomy abolished the rise in PRA during hypovolemia yet rats drank water normally. Moreover, aldosterone concentrations were substantially elevated by PEG treatment in the nephrectomized rats yet sodium appetite was abolished. These and other findings suggest that neither angiotensin nor aldosterone plays a prominent role in stimulating water and saline intakes during hypovolemia.
The glutamate dehydrogenase and glutamine synthetase activities of an obligate halophyte, Suaeda maritima var. macrocarpa and a glycophyte. Phaseolus vulgaris are compared in function of salinity (increasing concentrations of NaCl) of the culturing solution. In culture, addition of NaCl stimulates glutamine synthetase activity and lowers glutamine dehydrogenase activity in the aerial organs and in the roots of Suaeda as opposed to what is observed in the glycophyte. Hence the obligatory halophily of Suaeda is related to an increase of the glutamine synthetase activity in a sal-trich medium corresponding to the stimulation of nitrate reductase and proteogenesis.
The effect of 0.05 M and 1.5 M NaCl treatments on CHO cells during and after irradiation has been examined. Treatment with either hypotonic or hypertonic salt solutions during and after irradiation resulted in the fixation of radiation damage which would otherwise not be expressed. The half time for fixation was 4 to 5 min, and the increased expression of the potentially lethal damage by anisotonic solutions was mainly characterized by large decreases in the shoulder of the survival curve, as well as by decreases in DO. Fixation of radiation damage at 37 degrees C occurred to a much greater extent for the hypertonic treatment than for the hypotonic treatment and was greater at 37 degrees C than at 20 degrees C. Although both the hypotonic and hypertonic treatments during and after irradiation reduced or eliminated the repair of sublethal and potentially lethal damage, treatment during irradiation only, radiosensitized the cells when the treatment was hypotonic, and radioprotected the cells when the treatment was hypertonic. These observations are discussed in relation to salt treatments and different temperatures altering competition between repair and fixation of potentially lethal lesions, the number of which depends on the particular salt treatment at the time of irradiation.