Cl− fluxes across isolated,perfused gills of the chinese crab Eriocheir sinensis (M.Edw.) acclimated to fresh water

• 1.1. The movements of Cl⁻¹ have been studied in the so-called anterior and posterior gills of E. sinensis using radioactive ³⁶Cl⁻¹.
• 2.2. The anterior gills hardly show any significant movements of Cl⁻¹. They thus have a very low (if any) permeability to that ion. On the contrary, the posterior gills show both passive fluxes and an active inward movement of Cl⁻¹.
• 3.3. The Cl⁻¹ influx in the posterior gills is largely sensitive to the amount of K⁺ in the perfusion saline.

     

Proteolytic cleavage of band 3 protein in relation to anion transport in fish (Oncorhynchus mykiss) red blood cells

• 1.1. The effects of trypsin and chymotrypsin on HCO₃⁻/Cl⁻ exchange through red blood cell membranes of humans and trout were studied.
• 2.2. To measure the anion exchange we used a right-angle light-scattering technique by applying the Jacobs-Stewart cycle in ammonium solution and the osmotiration method at constant cell volume.
• 3.3. The Cl⁻ flux in human red blood cells remained unaltered after treatment with external trypsin and chymotrypsin while in trout red blood cells the flux decreased.
• 4.4. This partial inhibition of anion transport in fish, ranging from 30 to 40%,suggest that one or several of the cleavage sites in band 3 protein, essential for anion transport function, are exposed in fish red blood cells.
• 5.5. In human red blood cells the fragments of band 3 which are affected by proteolytic digestion, retain their tertiary structure because there is no influence on anion transport.

     

Sea-water tolerance in freshwater-resident arctic charr (Salvelinus alpinus)

• 1.1. Freshwater-resident Arctic charr acclimated for 2 months at 8°C, 15% were divided into four experimental groups in July and exposed to 1 and 8°C in 15 and 34% salinity.
• 2.2. Only slight changes in gill Na-K-ATPase activity, blood plasma osmolality and blood plasma concentrations of Cl⁻ and Mg²⁺ were found for the fish exposed to 1 or 8°C in brackish water.
• 3.3. When exposed to sea-water at 8°C, an increase in osmolality and in concentrations of Cl⁻ and Mg²⁺ took place during the first 2–3 days, after which it levelled off.
• 4.4. If exposed to sea-water at 1°C, however, marked increases were found for all parameters measured and all the fish were dead within 5 days of exposure.
• 5.5. These results show that freshwater-resident Arctic charr—if acclimated to brackish water—can survive in sea-water during summer if the environmental temperature is not too low.

     

Intestinal l-methionine transport in the cultured gilthead bream (Sparus aurata)

• 1.1. The influx and transepithelial movements of l-methionine and its effects on the electrophysiology and Na-Cl-transport in upper and lower intestine of the cultured fish, Spanis aurata, were measured.
• 2.2. The K_m and V_max of l-methionine influx into the tissues were higher in lower intestine than in upper intestine. A prominent diffusion-like transport component was also measured in both segments during influx experiments.
• 3.3. Net transepithelial fluxes of l-methionine (1 mM) were observed in both upper and lower intestine, this transport being Na⁺-dependent.
• 4.4. The two intestinal segments exhibited an electrical potential difference (PD) and a short circuit current (I_sc) serosa negative or near zero. Tissue conductance (G_t) was higher in posterior than in lower intestine.
• 5.5. Addition of l-methionine to the mucosal side of lower or upper intestine did not induce changes in PD in either part.
• 6.6. Isotopic fluxes of Cl⁻ or Na⁺ measurements under short circuit conditions showed that there were no net Cl⁻ or Na⁺ transport in either part.
• 7.7. l-Methionine additions to the mucosa did not induce changes in unidirectional fluxes of Cl⁻ or Na⁺ or in the (I_sc) in either the anterior or posterior intestine.

     

Biomines-stimulated phosphorylation and (Na+, K+-ATPase in the gills of the chinese crab,Eriocheir sinensis

• 1.1. Subcellular distribution of (NA⁺, K⁺-ATPase and ouabain-insensitive ATPase (Mg²⁺-ATPase) are compared in branchial tissues of the euryhaline crab, Eriocheir sinensis, acclimated to fresh water.
• 2.2. Both the anterior and posterior gills contain cAMP-dependent protein kinase and endogenous protein substrate for phosphorylation.
• 3.3. Phosphorylation occurs in both “particulate” and “soluble” subcellular fractions but its stimulation by cAMP is restricted to the “soluble” fraction.
• 4.4. serotonin (5-HT) and dopamine receptors are present only in the “light particulate” fraction isolated from the posterior gills.

• 1.(a) Serotonin and dopamine have no effect on the phosphorylation observed in a subcellular fraction alone.
• 2.(b) Activation of the phosphorylation by serotonin and dopamine is found when the soluble fraction (source of cAMP-dependent protein kinase) is added to the fraction P₃ from the posterior gills.
• 3.(c) No activation occurs with the fractions P₃ as well as P₁ or P₂ (not shown) from anterior gills of fresh water crab.
• 4.(d) Cyproheptadine, a serotonin receptor antagonist, inhibits the 5-HT dependent increase in phosphorylation.
• 5.(e) The dopamine receptor antagonist, chlorpromazine, inhibits dopamine-stimulated phosphorylation.
• 6.5. Ouabain mimics the effect of cyproheptadine on the serotonin-stimulated phosphorylation found in the posterior gills.

     

Sodium transport in red blood cells of lamprey LAmpetra fluviatilis

• 1.1. Unidirectional Na⁺ influx in lamprey red blood cells was determined using ²²Na as a tracer.
• 2.2. Total Na⁺ uptake and amiloride-inhibitable Na⁺ influx increased in a saturable fashion as a function of external Na⁺ concentration (Na_e).
• 3.3. At 141 mM Na_e, the average value of net Na⁺ influx was 13 ± 1.1 and the amiloride-sensitive Na⁺ influx was 5.3±1.1 mmol/l cells per hr (±SE).
• 4.4. The amiloride-sensitive component of Na⁺ influx was significantly activated by 10⁻⁵ M isoproterenol, by 2 × 10⁻⁵ M DNP, and by cell shrinkage.
• 5.5. Furosemide (1 mM) had no effect on the Na⁺ transport in red cells.
• 6.6. The residual amiloride-insensitive component of Na⁺ transport was a linear function of Na_e in the range of 5–141 mM. This transport seems to be accounted for by simple diffusion.

     

Peritubular Na-K exchange ion pump in maleate-treated frog kidney proximal tubular cells

• 1.1. After perfusion of isolated frog kidneys for 1 hr with 10⁻³ or 10⁻² M maleate Ringer, the peritubular membrane potential gradually declined in a dose-dependent manner.
• 2.2. The ouabain-like effects of maleate on cell Na and K activities were dose-dependent and smaller than the effects of zero K or 10⁻⁴M ouabain. Intracellular pH was not altered in the presence of 10⁻²M maleate.
• 3.3. The driving force for Na entry into the cell was reduced, respectively, to 81.4 and 58.4% (of control) in the presence of 10⁻³ and 10⁻² M maleate.
• 4.4. There was no histochemically detectable inhibition of proximal tubule Na-K ATPase activity during 3 hr of perfusion with 10⁻² M maleate.

     

Comparative nuclear magnetic resonance studies of diffusional water permeability of red blood cells from different species. V—Rabbit (Oryctolagus Cuniculus)

• 1.1. The diffusional water permeability (P_d) of rabbit red blood cell (RBC) membrane has been monitored by a doping nuclear magnetic resonance (NMR) technique on control cells and following inhibition with p-chloromercuribenzene sulfonate (PCMBS).
• 2.2. The values of P_d were around 6.3 × 10⁻³ cm/sec at 15°C, 7.0 × 10⁻³cm/sec at 20°C, 8.0 × 10⁻³ cm/sec at 25°C, 9.1 × 10⁻³ cm/sec at 30°C and10.7 × 10⁻³ cm/sec at 37°C.
• 3.3. Systematic studies on the effects of PCMBS on water diffusion indicated that the maximal inhibition was reached in 15 min at 37°C with 0.5 mM PCMBS.
• 4.4. The values of maximal inhibition were around 71–74% at all temperatures.
• 5.5. The basal permeability to water was estimated as 1.6 × 10⁻³cm/sec at 15°C, 2.0 × 10⁻³cm/sec at 20°C, 2.4 × 10⁻³cm/sec at 25°C, 2.6 × 10⁻³cm/sec at 30°C, and 3.1× 10^{−3 cm/secat 37°C}.
• 6.6. The activation energy of water diffusion was around 18 kJ/mol and increased to 27 kcal/mol after incubation with PCMBS in conditions of maximal inhibition of water diffusion.
• 7.7. The membrane polypeptide electrophoretic pattern of rabbit RBCs has been compared with its human counterpart.
• 8.8. The rabbit membrane contained a higher amount of spectrin (bands 1 and 2), while the band 6 (glyceraldehyde-3-phosphate dehydrogenase) was markedly less intense.
• 9.9. Considerable differences in the electrophoretic patterns of the two sources of RBC membranes appeared in the bands migrating in the band 4.5 region and in front of band 7, where some polypeptides were apparent in higher amounts in the rabbit RBC membrane.

     

Evidence for extracellular deamination of adenosine in the rat heart

• 1.1. In rat heart perfused with adenosine (10⁻⁶M), dilazep (10⁻⁴M) inhibited incorporation of adenosine into nucleotides (an index of nucleoside transport and phosphorylation) to a greater extent (70%) than metabolism to inosine and uric acid (40%) and actually increased the recovery of inosine to 30% of the adenosine infused.
• 2.2. Extrapolating for complete inhibition of transport suggested that 60% of adenosine metabolism was intracellular and 40% extracellular.
• 3.3. Static incubations of atria also gave an estimate for extracellular metabolism of 40%.
• 4.4. Adenosine deaminase was localised by immunocytochemistry to the extracellular surface of endothelial cells of small coronary arteries.
• 5.5. Extracellular deamination may explain the lack of effect of nucleoside transport inhibitors on responses to adenosine in rat heart.

     

Renal response to hypoxia in carp,Cyprinus carpio: Changes in glomerular filtration rate,urine and blood properties and plasma catecholamines of carp exposed to hypoxic conditions

• 1.1. Changes in glomerular nitration rate (GFR), urine and blood properties and plasma catecholamines of carp were investigated during and following hypoxia.
• 2.2. GFR and urine flow decreased with increased urinary concentrations of bio-components, except protein, in the course of hypoxia.
• 3.3. Decreases in blood pH, and increases in haematocrit value and plasma K⁺, Ca²⁺, Mg²⁺, inorganic phosphate (P_i), ammonia, lactic acid and catecholamines (CAs) were observed as hypoxia progressed.
• 4.4. Increased GFR and urine flow, and higher values for urinary components, except protein, compared with those of the control were found in the initial post-stress stage.
• 5.5. The possible significance of increased plasma CAs in relation to changes in renal function in hypoxic carp is discussed.

     

Sea water drinking as a homeostatic response to dehydration in hatchling loggerhead turtles Caretta caretta

• 1.1. Hatching Caretta caretta may lose up to 12% of their initial hatched weight from water loss during emergence from the nest.
• 2.2. After subsequent osmotic and excretory water loss in sea water, hatchlings will drink sea water (166 μl 100 g⁻¹ hr⁻¹) and return to their initial weight within 10–15 days, without feeding.
• 3.3. There were no significant changes in plasma osmolarity or sodium levels over this period.
• 4.4. This osmoregulatory strategy is in marked contrast to that seen in the estuarine crocodile, Crocodylus porosus.

     

Effects of aluminium and pH on calcium fluxes,and effects of cadmium and manganese on calcium and sodium fluxes in brown trout (Salmo trutta L.)

• 1.1. Simultaneous measurement of calcium fluxes in brown trout, at low external [Ca] (20 μ mol 1⁻¹), provided evidence of active uptake of Ca from the medium.
• 2.2. At pH 4.5, calcium influx was inhibited and efflux was stimulated.
• 3.3. Cd and Mn, but not Al, at concentrations within the ranges found in acid waters experiencing fish population decline, inhibited calcium influx. Efflux was unaffected.
• 4.4. Cd and Mn stimulated sodium influx and efflux.

     

The mechanism of interaction of ceruloplasmin with superoxide radicals

• 1.1. The mechanism of interaction of CP with O₂ radicals in chemical and enzymatic systems of Superoxide radical generation as well as in the pulse radiolysis technique was studied.
• 2.2. It is found that CP does not exert any kinetic influence on the decomposition of Superoxide radical and, unlike SOD, cannot catalyze the reaction of disproportionation of these radicals in systems with chemical and enzymatic generation of O₂⁻.
• 3.3. The data obtained confirm the suggestion that CP interacts with precursors of ₂⁻ radicals.
• 4.4. The irradiation of CP does not change its inhibiting activity in the reaction of the formation of Superoxide radicals in systems with enzymatic O₂⁻ generation, but decreases its oxidase activity.
• 5.5. The results obtained demonstrated that the increase in the radiation dose resulted in the decrease of the inhibiting activity of SOD, whereas the activity of CP did not change.

     

Purification and properties of tetralysine endopeptidase from Escherichia coli AJ005

• 1.1. A new tetralysine endopeptidase from Escherichia coli AJ005 has been purified about 135-fold.
• 2.2. The peptidase seems to be specific to tetralysine among lysine homopolymers.
• 3.3. The optimal pH was about 7.5
• 4.4. The activity was inhibited by KCN but not inhibited by soybean trypsin inhibitor.
• 5.5. The apparent K_m value was 2.5 × 1O⁻³ M for tetralysine.

     

Thermostability and activation by divalent cations of the membrane-bound inorganic pyrophosphatase of Rhodospirillum rubrum

• 1.1. The activation energy of the membrane bound H⁺-pyrophosphatase is 44.9 k J·mol⁻¹, for the detergent solubilized enzyme is 55.9 kJ·mol⁻¹.
• 2.2. The Arrhenius plots obtained for pyrophosphatases of Rhodospirillum rubrum show no breaks.
• 3.3. At 70°C, the membrane-bound pyrophosphatase is more stable in the presence of either Mg²⁺ or Zn²⁺ than in their absence.
• 4.4. At 65°C, an activator effect of Mg²⁺ or Zn²⁺ was observed. Nevertheless, at 70°C no activation was obtained.
• 5.5. The activator effects of Mg²⁺ or Zn²⁺ were depended of their concentration.

     

A halogenated amino acid-containing sperm activating peptide and its related peptides isolated from the egg jelly of sea urchins,Tripneustes gratilla,Pseudoboletia maculata,Strongylocentrotus nudus,Echinometra mathaei and Heterocentrotus mammillatus

• 1.1. Twenty-eight peptides were isolated from the egg jelly of sea urchins, Tripneustes gratilla, Pseudoboletia maculata, Strongylocentrotus nudus, Echinometra mathaei (type A and B) and Heterocentrotus mammillatus and their amino acid sequences were determined.
• 2.2. Two of the peptides obtained from T. gratilla egg jelly possessed a bromophenylalanine (Br-Phe) residue in their sequences (Gly-(Br-Phe)-Asn-Leu-Asn-Gly-Gly-Gly-Val-Gly and Gly-(Br-Phe)-Asp-Leu-Asn-Gly-Gly-Gly-Val-Gly).
• 3.3. All of the peptides elevated cyclic GMP concentrations in the spermatozoa of the respective sea urchin and caused a shift in the apparent mol. wt of a major sperm protein of the respective sea urchin.
• 4.4. They stimulated respiration rates of the spermatozoa of Hemicentrotus pulcherrimus as well as their own species.
• 5.5. One-half maximal concentrations of the peptides for respiratory stimulation of H. pulcherrimus spermatozoa were between 10⁻¹¹ M and 10⁻⁹ M except a methionine-containing peptide which was about 10⁻⁷ M.

     

Aluminium and calcium affect the perivitelline fluid in fish eggs

• 1.1. Microelectrodes have been used to measure K⁺ activities and electrical potential differences between the perivitelline fluid (pvf) of the eggs of pike (Esox lucius) and surrounding water in a range of pH, calcium and aluminium concentrations.
• 2.2. Potential differences between pvf and water are decreased by Ca²⁺ (10⁻³ M) while Al³⁺ (18 × 10⁻⁶ M) reverses the polarity of the potential difference.
• 3.3. K⁺ activities in the pvf of eggs in 10⁻⁴M KCl + 10⁻⁵M NaCl are decreased by Ca²⁺(10⁻³ M).
• 4.4. The results are discussed with reference to ion-exchange theory and chorion permeability.

     

Bioelectrical potentials across the mantle epithelium of Achatina fulica

• 1.1. The shell side of the mantle of Achatina fulica is several millivolts positive to the blood side in vitro.
• 2.2. The electrical potential does not depend on Na⁺, Ca²⁺, Mg²⁺, K⁺ or HCO₃⁻ but requires the presence of chloride on the shell side.
• 3.3. The potential difference and short-circuit current ranged from 3.0 to 30.0 mV and 15.0 to 75 μA/cm² with averages at 10m V and 50 μA/cm² respectively.
• 4.4. The electrical gradient is reduced by 2,4-dinitrophenol, thiocyanate and furosemide but not by ouabain, CO₂ or acetozolamide.
• 5.5. It is suggested that the nature and mechanism of electrogenesis in Achatina parallels that of the Helix mantle.

     

Blood changes in japanese eels,Anguilla japonica,experimentally infected with typical or atypicalAeromonas salmonicida

• 1.1. Changes in the blood and in the rate of oxygen consumption of Japanese eels injected intramuscularly in the head with a lethal dose of typical or atypical Aeromonas salmonicida at 20°C were investigated.
• 2.2. Eels infected with the bacteria became moribund within 4 to 6 days, and then died within 1 day.
• 3.3. The O₂ consumption rate and blood parameters changed markedly with infections. The responses of hosts to infection by the two kinds of bacteria differed with regard to the following four points: blood pH, plasma Cl⁻, lactic acid, and the numbers of granulocytes and lymphocytes.
• 4.4. The responses of eels infected with atypical A. salmonicida were larger and more rapid than those of eels infected with typical A. salmonicida.

     

The effect of triiodothyronine on glucose utilization in adipocytes from obese rats

• 1.1. In the presence of insulin, 10⁻⁵ M 3,3',5-triiodothyronine (T₃) treatment for 1/2 hr decreased fatty acid synthesis 35% only in adipocytes from lean rats, whereas at 10⁻¹¹ M through 10⁻⁷M T₃ the obese adipocytes had nearly a 20% increase in fatty acid synthesis.
• 2.2. A 2 hr pretreatment of adipocytes with 10⁻⁹ and 10⁻⁷ M T₃ decreased insulin-stimulated fatty acid synthesis by nearly 20% in both lean and obese adipocytes.
• 3.3. In the absence of insulin, the 2 hr pretreatment with 10⁻⁹ M T₃ resulted in a 45% increase in lean adipocyte fatty acid synthesis, though the obese adipocytes required at least 10⁻⁷ M T₃ for 2 hr to increase the non-insulin-stimulated fatty acid synthesis by 50%.
• 4.4. At 10⁻⁹M T₃ concentrations non-insulin-stimulated fatty acid synthesis was increased by 200% in lean adipose tissue explants, but obese adipose expiants were not significantly affected under these conditions.
• 5.5. The addition of 10⁻⁹ M T₃ plus insulin to the explant media decreased fatty acid synthesis by 35% in both the lean and obese tissues.
• 6.6. The results also imply that the low T₃ status of the obese rat may be contributory to the elevated fatty acid synthesis observed in obese adipocytes.