Specific sodium-22 binding to a purified sodium + potassium adenosine triphosphatase. Inhibition by ouabain

Analysis of sodium-22 binding to purified sodium + potassium ion-activated adenosine triphosphatase (Na+, K+)-ATPase reveals the presence of two classes of binding sites. The higher affinity site (Kd = 0.2 mM) binds 6 to 7 nmol of sodium per mg of protein. Pretreatment of (Na+, K+)-ATPase with ouabain blocks the binding of sodium to this higher affinity site. Neither heat-denatured enzyme nor phospholipids extracted from the (Na+, K+)-ATPase contain a ouabain-inhibitable, higher affinity sodium binding site. The ouabain enzyme complex therefore appears to contain altered binding sites for cations.

Salt-induced changes in sodium transport across the skin of the euryhaline toad, Bufo viridis

1. Euryhaline toads (Bufo viridis) were adapted to either distilled water, 115 or 200 mM-NaCl solutions. Na transport across the skin of these animals was studied in in vitro preparations. 2. Salinity adaptation caused a reduction in transepithelial potential and short-circuit current across the skin, and increased its electrical resistance. 3. Na influx across the skin was decreased. The reduction accounted fairly well for the measured reduction in short-circuit current. 4. Short-term Na uptake at the outer barrier of the skin was greatly reduced in preparations from salt adapted animals. Amiloride, which usually inhibits Na uptake, did not affect it in skins from salt adapted toads. 5. Sodium conductance decreased by a factor of three in skins from 115 mM-NaCl adapted toads, and to zero in skins from 200 mM-NaCl adapted animals. Shunt conductance was only little affected by the salinity of adaptation. 6. 'Amiloride-sensitive component' of transepithelial Na transport was 55, 21-5, and 4-5 muA/cm-2 in skins from toads which were adapted to distilled water, 115, and 200 mM-NaCl solutions, respectively. 7. It is concluded that the effect of salinity adaptation on the skin of the toad is to reduce the number of Na selective sites at the outer barrier. This change is reflected in a decrease in the 'amiloride-sensitive component' of Na transport across the skin, and could not be increased by aldosterone. Other changes may occur as secondary to that.

A radioactive hapten-binding assay for measuring antibodies to the pentapeptide determinant of peptidoglycan

A major portion of the humoral immune response to peptidoglycans is directed against the non-cross-linked pentapeptide side chains of these ubiquitous bacterial antigens. At present, no specific and sensitive assay for pentapeptide antibody determination is available. Therefore, a radioimmunoassay has been developed which employs the synthetic pentapeptide hapten L-Ala-gamma-D-Glu-L-Lys-D-Ala-D-Ala, labeled by the active ester method of Bolton and Hunter to high specific activities (6.74 to 18.18 muCi/mug) with 125I, and used as a reagent for measuring pentapeptide antibody. A-variant streptococcal antisera, known to contain pentapeptide antibodies as shown by quantitative precipitation, would bind more than 95% of the radiolabeled hapten in contrast to 2 to 3% by preimmune rabbit sera. Specificity of the binding reaction was demonstrated by inhibition experiments imploying various synthetic oligopeptides related or unrelated to the pentapeptide in the radioimmunoassay. Binding curves established with serial dilutions of peptidoglycan antiserum were linear from 15 to 500 mug/ml of antibody permitting pentapeptide antibody measurement within this range. Comparative data on pentapeptide antibody determinations by quantitative precipitation and radioimmunoassay are given and the time course of the production of this antibody in 14 rabbits hyperimmunized with A-variant streptococcal vaccine is reported.

Changes in the bidirectional sodium flux across the intestinal mucosa in Crohn's disease

Bidirectional sodium flux across the intestinal mucosa was measured in a group of 10 patients with Crohn's disease treated in the past by panproctocolectomy with ileostomy and compared with a similarly treated group of 11 patients with ulcerative colitis. All of them were in good health at the time of the study and a recent radiological examination of the small intestine was normal. A significant reduction in bidirectional sodium flux was found in those patients with Crohn's disease and suggests that the intestinal mucosa is involved to a greater extent than can be judged by radiological appearances alone. This adds weight to the concept that Crohn's diseases is a diffuse rather than a focal lesion of the gastrointestinal tract.

Active chloride secretion by in vitro guinea-pig seminal vesicle and its possible relation to vesicular function in vivo

1. The guinea-pig seminal vesicle in vivo is characterized by a transmural electrical potential difference of approximately 11 mV with the lumen electrically negative with respect to the interstitial fluid. The concentrations of Na, Cl and K in the vesicular fluid are 13, 15, and 0-4 mM, respectively. 2. When mounted as a flat sheet in a short-circuit apparatus, guinea-pig seminal vesicles initially undergo a decline in the transmural electrical potential difference and short-circuit current ('low phase') followed by a spontaneous increase in these parameters ('high phase'). 3. During the low phase, net C1 movements across the tissue do not differ significantly from zero, and there is a small 'residual' current that is unaccounted for. 4. During the high phase, there is a significant active C1 secretion into the mucosal solution, not detectable net movement of Na and an unaccounted for or 'residual' current that is equal to that found in the low phase. 5. Theophylline, dibutyryl-3'-5' cyclic adenosinemonophosphate,prostaglandin E1 and prostaglandin F2alpha markedly stimulate the transmural electrical potential difference and short-circuit current during the low phase, but have no effect when added to the bathing solution during the high phase. 6. Diffusion potentials determined across in vitro seminal vesicles suggest that the spontaneous transmural electrical potential difference in vivo may be attributable to the large ionic asymmetries between the vesicular fluid and the plasma. 7. It is postulated that two phases are involved in the elaboration of seminal vesicular fluid. The initial phase, following emptying of the vesicle, is characterized by the secretion of electrolytes, organic molecules and water. Active C1 secretion presumably regulated by intracellular cyclic adenosinemonophosphate and/or prostaglandins may be the driving force for this initial secretion of electrolytes. Following this secretory phase, electrolytes and water are reabsorbed, thereby concentrating the organic components in the vesicular reservoir.

Analysis of unidirectional fluxes of sodium during diarrhea induced by Clostridium perfringens enterotoxin in the rat terminal ileum

Net intestinal transport of sodium in vivo, in control and enterotoxin (Clostridium perfringens)-treated rats, was resolved into two unidirectional fluxes, influx from and efflux into the lumen of the terminal ileum. In rats treated with the toxin, sodium influx remained similar to control values even during fluid and electrolyte loss to the lumen. Net loss of sodium was shown to be due to nearly a twofold increase in sodium efflux to the lumen in toxin-treated animals. There was only slight histopathological damage to the mucosa, especially noticeable at the tips of villi.

Effect of histamine on immunoreactive gastrin in gastric juice and in serum

Due to recent reports claiming that gastrin is present in the gastric juice, the method for gastrin determination has been evaluated. Separate experiments showed that gastrin added to gastric juice disappears rapidly if the juice is not boiled or neutralized. A total of 82 patients with various abdominal disorders were examined. No or only a trace amount of gastrin was found in untreated, boiled, or boiled and neutralized gastric juice in every patient, including three patients with achlorhydria. Histamine injection (0.04 mg. per kilogram, subcutaneously) did not influence this and was without effect upon serum gastrin concentrations of nine duodenal ulcer patients. Because gastrin apparently is degraded rapidly by gastric juice, this study does not necessarily disprove that gastrin is secreted into the stomach. However, the virtual absence of gastrin in all specimens examined, including some collected directly upon boiling water bath during continuous gastric aspiration lends no support to this speculation. Because gastrin does not survive even a short exposure to gastric juice without degradation, we suggest that earlier reports on the presence of gastrin within the stomach are questionable.

Distribution of sodium and potassium in chronic obstructive pulmonary disease

The body electrolyte composition of 34 patients with severe chronic obstructive pulmonary disease and without complications or medications known to influence body sodium or potassium was studied. Exchangeable sodium, exchangeable potassium, extracellular water, and total body water were measured using radioisotope dilution techniques. From these values and serum sodium and potassium levels, the intracellular water, intracellular concentrations of sodium and potassium, and factors to estimate lean body mass were calculated. Normal values were predicted for factors that vary with weight, age, and sex--exchangeable sodium, exchangeable potassium, total body water, extracellular water, intracellular water, and estimates of lean body mass--for each subject using regression equations that took into account the variables. For values that do not vary with weight or age--residual sodium and intracellular concentration of potassium--comparisons were made with values from our control subjects. The patients with chronic obstructive pulmonary disease showed a slower rate of potassium exchange than the control subjects, requiring at least 48 hours. There was also an increase in residual sodium composed of intracellular sodium and exchangeable bone sodium. The possibilities that the abnormalities could be ascribed to congestive heart failure, loss of lean tissue, or to a slowly functioning sodium pump were considered.

Slow phase hemolysis in hypotonic electrolyte solutions

When a population of erythrocytes is partially hemolyzed the time course of hemolysis can be divided into a fast phase and a slow phase. The slow phase occurs with both rapid and gradual addition of the hypotonic medium (rapid and gradual hemolysis). There is no difference in the osmotic fragility of erythrocytes remaining at 60 minutes after rapid or gradual hemolysis. Erythrocytes near their critical hemolytic volume have an equimolar ouabaininsensitive sodium-potassium exchange. Critical non-hemolytic swelling with resulting stress on the membrane appears requisite to slow phase hemolysis since more non-penetrant sucrose is required to prevent slow phase lysis rather than that which would be predicted from the intracellular colloid osmotic pressure due to hemoglobin. Sucrose protection from slow phase hemolysis thus depends not only on counter-balancing the colloid osmotic pressure, but also removal of sufficient intracellular water to prevent critical membrane strain. This model is consistent with that proposed by Katchalsky. Irreversible membrane changes associated with hypotonic stress manifested by persistent stomatocytic shape change and membrane wrinkling on return of cells to isotonicity appear to be due to critical changes in membrane components. Such cells, having normal indices and specific gravity are less deformable than control cells in 2.8 mum pore size polycarbonate filters.

Use of radioimmunoassays to determine the concentration of streptococcal group-specific antibodies in rabbit antisera

A radioimmunoassay was developed for the quantitation of antibodies to the Group A, A-variant, and C carbohydrates in rabbit streptococcal antisera. The assay employs radiolabeled purified Group carbohydrate which has been tyrosylated to allow for incorporation of 125-I. This assay has an advantage over the intitative precipitin test because it measures non-precipitating antibody in addition to precipitating antibody. Furthermore, 7S anti-IgG in rabbit antisera give a falsely elevated value for the antibody concentration in the quantitative precipitin test. This did not occur with the radioimmunoassay. The assay described is reproducible, sensitive, and uses little antisera.

Firearm residue detection by instrumental neutron activation analysis

Work leading to an improved technique for firearm discharge residue detection by neutron activation is described. The troublesome and time-consuming postirradiation chemistry has been eliminated; also, sample size has been minimized to accommodate some 130 samples per irradiation capsule. To put the method in a proper perspective, previous work has been referenced and discussed.

The interaction of ATP-analogues possessing a blocked gamma-phosphate group with the sodium pump in human red cells

1. The (Na++K+)-ATPase of red cell membranes is unable to hydrolyse ATP-analogues in which the oxygen atom linking the beta- and gamma-phosphate groups is replaced by a minusCH2minus or minusNH-bridge. 2. In resealed ghosts both these ATP-analogues support K:K exchange but not Na:K exchange. ATP supports both modes of operation of the sodium pump, whereas neither occurs without any nucleotide. 3. These results support the hypothesis that ATP is needed as a cofactor for K:K exchange to occur, and make it extremely unlikely that phosphorylation from ATP is involved.

The Compu-pet 100: a versatile dispenser-diluter for the mechanization of microbiological techniques

The Compu-pet 100 diluter/dispenser is a versatile and accurate instrument which can be employed for a wide variety of microbiological tests and techniques. Time in performing tests is often more than halved when the diluter is used. Large numbers of tests can be performed with minimal fatigue.

Ionic relations and electrical properties of isolated oocytes of Bufo bufo with special reference to removal of extracellular chloride

1. The efflux rate coefficients of sodium, potassium and chloride from immature oocytes of the toad Bufo bufo have been measured and found to be respectively, 0.0069, 0.0023 and 0.0034 min(-1).2. Replacement of external chloride by sulphate resulted in a fall in chloride efflux of about 50%. This has been interpreted in terms of exchange diffusion.3. The membrane conductance has been measured and found to be 0.14 x 10(-3) mhos cm(-2) in good agreement with the value calculated from the flux data, 0.12 x 10(-3) mhos cm(-2), after taking account of the chloride exchange diffusion fraction.

Effects of cytochalasin B on the response of toad urinary bladder to vasopressin

A combined physiological and morphological study of the effects of cytochalasin B (CB) on the toad urinary bladder has been carried out. CB inhibits the hydro-osmotic response to vasopressin without altering basal water permeability or diffusion, or the increase in (3)H(2)O diffusion observed after hormone addition. Although CB increases [(22)Na]-, [(36)Cl]-, and [(14)C]urea fluxes, and decreases transepithelial potential, no alteration in basal short-circuit current, the vasopressin-induced increase in this parameter, or [(14)C]inulin permeability occurs. In the absence of hormone, CB does not markedly alter the structure of the toad bladder. However, in the presence of vasopressin, CB induces the formation of large intracellular vacuoles. These results suggest a possible coupling of solute and water movement across the tissue.

Purified acetylcholine receptor: its reconstitution to a chemically excitable membrane

Association of purified acetylcholine receptor from Torpedo californica electroplax with lipids from the same organism results in a vesicular membrane system in which the receptor protein is oriented so that all neurotoxin binding sites appear to be on the outer surface. The reconstituted system is chemically excitable by acetylcholine and carbamylcholine, as measured by (22)Na(+) efflux. This excitability is specifically blocked by the antagonist alpha-bungarotoxin. These results demonstrate that the purified receptor macromolecule contains not only the specific neurotransmitter binding site but also the molecular elements necessary for ion translocation in order to effect postsynaptic depolarization.

Sodium Exchange in the Cytoplasm and Nucleus of Amphibian Oocytes

Oocytes of Rana pipiens were incubated in 22Na-Ringer's solution and 22Na-23Na exchange in the nucleus and cytoplasm followed by low-temperature microdissection. Cytoplasmic sodium consists of 2 kinetic fractions: the larger (88%) slowly exchanging (t½ ∼ 2 days), and the smaller (12%) rapidly exchanging (t½ ∼ 53 min). Nuclear sodium consists of a single fraction whose concentration is similar and whose rate constant is identical with that of the rapidly exchanging cytoplasmic fraction. Our findings are consistent with a model of compartmentalization in which rapidly exchanging sodium is nearly uniformly distributed in the water of the nucleus and cytoplasm and its exchange limited by movement through the cell surface. On the other hand, slowly exchanging sodium is restricted to the cytoplasm, sorbed to or sequestered in some as yet unidentified cytoplasmic constituent.

Volume reabsorption, transepithelial potential differences, and ionic permeability properties in mammalian superficial proximal straight tubules

This paper describes experiments designed to evaluate Na(+) and Cl(-) transport in isolated proximal straight tubules from rabbit kidneys. When the perfusing solution was Krebs-Ringer buffer with 25 mM HCO(3) (-) (KRB) and the bath contained KRB plus 6% albumin, net volume reabsorption (J(v), nl min(-1) mm(-1) was -0.46 +/- 0.03 (SEM); V(e), the spontaneous transepithelial potential difference, was -1.13 +/- 0.05 mV, lumen negative. Both J(v), and V(e), were reduced to zero at 21 degrees C or with 10(-4) M ouabain, but J(v), was not HCO(3) (-) dependent. Net Na(+) reabsorption, measured as the difference between (22)Na(+) fluxes, lumen to bath and bath to lumen, accounted quantitatively for volume reabsorption, assuming the latter to be an isotonic process, and was in agreement with the difference between lumen to bath (22)Na(+) fluxes during volume reabsorption and at zero volume flow. The observed flux ratio for Na(+) was 1.46, and that predicted for a passive process was 0.99; thus, Na(+) reabsorption was rationalized in terms of an active transport process. The Cl(-) concentration of tubular fluid rose from 113.6 to 132.3 mM during volume reabsorption. Since V(e), rose to +0.82 mV when tubules were perfused with 138.6 mM Cl(-) solutions, V(e) may become positive when tubular fluid Cl(-) concentrations rise during volume reabsorption. The permeability coefficients P(Na) and P(Cl) computed from tracer fluxes were, respectively, 0.23 x 10(-4) and 0.73 x 10(-4) cm s(-1). A P(Na)/P(Cl) ratio of 0.3 described NaCl dilution potentials at zero volume flow. The magnitudes of the potentials were the same for a given NaCl gradient in either direction and P(Na)/P(Cl) was constant in the range 32-139 mM NaCl. We infer that the route of passive ion permeation was through symmetrical extracellular interfaces, presumably tight junctions, characterized by neutral polar sites in which electroneutrality is maintained by mobile counterions.

Diffusion of sucrose, sodium, and water in ventricular myocardium

The cumulative fluxes of radioactive sucrose, sodium, and water across a sheet of cat right ventricle were studied simultaneously to obtain the apparent tissue diffusion coefficients for extravascular diffusion at 37°C. The sucrose data fitted the equations for diffusion in tortuous channels in a plane sheet with a tortuosity factor, λ, of 2.11 ± 0.11 (mean ± SE, n = 10). The fit of the earliest data before attainment of steady state was improved by assuming a Gaussian distribution of diffusion path lengths through the extracellular space, but λ was only changed by a few percent. The sucrose diffusion channel contained 0.27 ± 0.03 ml of total tissue water, which is more than measured by others but still less than the expected sucrose space. The steady-state data for sodium agreed with the model for extracellular diffusion using λ and the area available for diffusion for sucrose when sodium equilibration with a dead-end pore volume (presumed to be intracellular) was taken into account. The cumulative flux data for water were monotonic and lacked secondary inflections. Thus the apparent tissue diffusion coefficients for sucrose, sodium, and water were (in 10⁻⁶ cm²/s) 1.77 ± 0.23, 5.13 ± 0.68, and 7.39 ± 0.99, respectively, representing a reduction to 23% of the free diffusion coefficient for sucrose and sodium and 22% for water.