Evidence for the presence of ion pumps in the photophores of two mesopelagic fishes: Argyropelecus and maurolicus

• 1.l. Adenosine triphosphatase (ATPase) activity has been measured on homogenates of photophores from the two mesopelagic fishes Argyropelecus and Maurolicus. This activity is equivalent for both fishes when reported to the protein content as is their O₂ consumption.
• 2.2. The activity is optimal at pH 6.8–7.5. It is not specific for ATP since GTP, ITP, UTP and CTP are also hydrolyzed to a significant extent. It is also not specific for Mg²⁺, the activity being equivalent (Argyropelecus) or higher (Maurolicus) with Ca²⁺ and high also with Co²⁺ and Mn²⁺
• 3.3. Twenty to 30 per cent of the activity measured at pH 7.4 is probably due to the mitochondrial ATPase as it is shown by oligomycin and venturicidin inhibition.
• 4.4. Activities of both fishes photophores are partly inhibited by N-N'-dicyclohexylcarbodiimide (DCCD), azide, LaCl₃, vanadate, diethylstilbestrol (DES) and N-ethylmaleimide (NEM) which are all inhibitors of ionic pumps.
• 5.5. Argyropelecus activity is sensitive to ouabaïn.
• 6.6. Our results show the presence of ionic pumps in Argyropelecus and Maurolicus photophores. If there is evidence for the absence or very low activity of a H⁺ pump, it is sure that Argyropelecus at least possess a Na⁺K⁺-ATPase.
• 7.7. The significance of a high protein content in Maurolicus photophores and of a large inorganic phosphate concentration in Argyropelecus is discussed.

     

Ionic dependence and vanadate sensitivity of (Na+, K+)-ATPase isolated from branchial sac of ascidians

• 1.1. Ion dependence and vanadium-induced inhibition on branchial sac ATPase in five species of ascidian Phlebobranchiata (vanadium-accumulating) and Stolidobranchiata (iron-accumulating) were studied.
• 2.2. The ATPase was obtained from the microsomal fraction, which was prepared from each ascidian branchial sac.
• 3.3. The ATPase was dependent on Mg²⁺ and activated by exogenous Na⁺ + K⁺.
• 4.4. Ouabain inhibited the ATPase activity in vitro, 10 μM to 100 μM vanadate, in vitro, suppressed the (Na⁺, K⁺)-ATPase.

     

The participation of ionic strength and pH in the contraction induced in Vorticella by calcium and magnesium

• 1.1. Glycerinated stalks of Vorricella convallaria may be induced to contract by the application of either Ca²⁺ or Mg²⁺, and the contractions vary complexly as a function of pH.
• 2.2. The coiling that occurs in the presence of Mg²⁺ is atypical, and the effect of ionic strength is to prevent coiling.
• 3.3. The Ca²⁺ -contractions are typical of living vorticellid coiling, and those occurring at pH 6.8 and 7.0 are inhibited at low ionic strength and enhanced at high ionic strength.
• 4.4. High concentrations of Ca²⁺ abolish the ionic strength repression of contraction.

     

Effects of K+, Ba2+ and Ca2+ on the excitable membrane in Paramecium tetraurelia

• 1.1. The effects of Ba²⁺ and K⁺ ions on the membrane currents of Paramecium tetraurelia under a voltage clamp were investigated.
• 2.2. External Ba²⁺ suppresses the inward-going K-current and the Ca-induced K-outward current and changes the activation and inactivation kinetics of transient inward current through the Ca-channel.
• 3.3. K⁺ increases the Ca-induced K-conductances but little affects the leakage conductance.
• 4.4. The resting potentials by changing those ionic concentrations shift the voltage sensitivities of all voltage sensitive channels, simultaneously.
• 5.5. The competition between ions to the channel responses was discussed.

     

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.

     

Inhibitors of active Ca2+ uptake by fragments of the sarcoplasmic reticulum of lobster muscle

• 1.1. Vesicles from the sarcoplasmic reticulum of lobster muscle accumulate Ca²⁺ if supplied with ATP as an energy source. A search was undertaken for inhibitors of Ca²⁺ transport.
• 2.2. p-Hydroxymercuribenzoate can completely inhibit Ca²⁺ transport and ATP hydrolysis. 2–4 Dinitrophenol inhibits uptake but not hydrolysis.
• 3.3. Sr²⁺, Ba²⁺ and Zn²⁺ inhibit uptake, perhaps by competing with Ca²⁺ for a carrier.
• 4.4. The vesicles contain acetylcholinesterase. Anticholinesterases can reduce —but not abolish—Ca²⁺ uptake. Acetylcholine has no effect on the activity of the vesicles.
• 5.5. Ca²⁺ uptake is not affected by Mn²⁺, glutamate, pilocarpine, carnosine, caffeine, strophanthidin or tetraethylammonium.
• 6.6. K⁺ is needed for maximal activity of the uptake system but not for ATP hydrolysis. Apparently K⁺ enhances the coupling between the energy supply and the carrier mechanism.

     

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.

     

Calcium-dependent potassium conductance in the photoresponse of a nudibranch mollusk

• 1.1. The response to light of Hermissenda photoreceptors when recorded intracellularly without interference from synaptic and action potentials consisted of three phases: an early depolarization (ED) followed by hyperpolarization (dip) and subsequent depolarization (tail).
• 2.2. The ED and the dip were associated with increased membrane conductance while decreased membrane conductance was involved with the tail.
• 3.3. The dip reversal potential was − 82.1 ± 5.3 mV and its amplitude varied inversely with the log of [K⁺].
• 4.4. Perfusing with agents which block K⁺ current like 4AP, Quinine, Quinidine or injection of TEA eliminated the dip and its associated increased membrane conductance, thus further supporting the role of K⁺ conductance in producing the dip.
• 5.5. The dip was enhanced by increased [Ca²⁺]_o, reduced by decreased [Ca²⁺]_o and abolished together with its associated increased membrane conductance when perfused with either D600, Cd²⁺, Mg²⁺, Mn²⁺, or Co²⁺, which block transmembrane Ca²⁺ current.
• 6.6. The dip and its associated increased membrane conductance were abolished by intracellular injection of EGTA and enhanced by perfusion with Ruthenium red.
• 7.7. Intracellular injection of Ca²⁺ mimicked the dip: membrane conductance was increased and the cell hyperpolarized.
• 8.8. These results indicate that the increase in intracellular [Ca²⁺] is primarily responsible for the light-induced increase of K⁺ conductance during the dip. The possible source of the Ca²⁺ is, at least in part, extracellular due to activation of an inward Ca²⁺ current.

     

The effects of heavy metal ions on Ca2+ ATPase extracted from fish gills

• 1.1. The gills of the freshwater fish Rutilus rutilus have been shown to contain a subcellular membrane fraction which is rich in the enzyme Ca²⁺ ATPase.
• 2.2. The enzyme is maximally activated by Ca²⁺ or Mg²⁺ ions at a concentration of about 2 mM but is not affected by Na⁺ or K⁺ ions or by ouabain.
• 3.3. In vitro the enzyme is inhibited by Cu²⁺, Pb²⁺, Zn²⁺ and Hg²⁺ ions at concentrations below 10 μM.
• 4.4. Copper ions at concentrations below 0.2 μM appear to induce the formation of additional enzyme units when applied to fish gills in vivo.

     

Osmoregulation in the brook trout,Salvelinus fontinalis—II. Effects of size,age and photoperiod on seawater survival and ionic regulation

• 1.1. Brook trout (Salvelinus fontinalis) of a single genetic stock, and hatched at the same time, were raised under two photoperiod and two feeding regimes to obtain fish of the same age but with different sizes and photoperiod experiences. In 11 experiments over 1.5 firs, fish were gradually exposed to 32 ppt seawater for 20 days to investigate the ontogeny of salinity tolerance.
• 2.2. Daily changes in plasma osmolarity, [Na⁺], [Cl⁻], [K⁺], [Mg²⁺], thyroxine, hematocrit and gill Na⁺,K⁺-ATPase during adaptation to 10, 20 and 32 ppt were examined in one experiment.
• 3.3. Size was the primary determinant of seawater survival (r² = 0.77) the effect of size on seawater survival slowed after fish reached a fork length of 14 cm. The effect of age on seawater survival (r² = 0.65) was through its covariance with size.
• 4.4. Photoperiod affected seawater survival only through its influence on the timing of male maturation, which decreased salinity tolerance.
• 5.5. Regulation of plasma osmolarity, [Na⁺], [Cl⁻], [K²⁺], [Mg²⁺] and hematocrit in sea water increased linearly with size over the entire range of sizes (6–32 em).
• 6.6. Gill Na⁺,K⁺-ATPase activity after 20 days in seawater decreased with increasing size of brook trout, possibly reflecting decreased demand for active ion transport in larger fish.
• 7.7. Plasma thyroxine concentrations declined in seawater, but no definitive role of this hormone in seawater adaptation was found.
• 8.8. Size dependent survival and osmoregulatory ability of brook trout is compared to other salmonids and a conceptual model is developed.

     

Influence of deionized water supplemented or not with different ions on prolactin cell activity and osmotic regulation in the goldfish

• 1.1. Goldfish were kept in deionized water (DW), DW + Na⁺ (0.35 mM), DW + K⁺ (0.05 mM), DW + Ca²⁺ (2mM) and DW + Mg²⁺ (0.2 mM). In Ca-free environments, prolactin cells appear unaffected. Stimulated calcium-sensitive cells (pars intermedia) may elaborate a hypercalcemic factor.
• 2.2. Fecal excretion, reduced in all groups, remains noticeable in DW + Ca²⁺
• 3.3. Ionic losses, very low in all groups, are minimal in DW. Supplementation with K⁺ increases Na⁺ loss.
• 4.4. Plasma Na⁺ Ca²⁺, and osmolarity decrease in DW, and still more in DW + K⁺. Ca²⁺' and Mg²⁺ partly suppress hyponatremia.
• 5.5. In goldfish kept in DW and subsequently in DW + Ca²⁺, calcemia increases.

     

A comparison of the effect of alternating current electronarcosis,rectified current electronarcosis and chemical anaesthesia on the blood physiology of the freshwater bream Oreochromis mossambicus (peters)—III. The effect on the plasma electrolytes Ca2+, Na+ and K+ and on the osmotic pressure of the blood

• 1.1. The effects of alternating current electronarcosis, rectified current electronarcosis and chemical anaesthesia (benzocaine hydrochloride) on plasma electrolytes and on the osmotic pressure of the blood of the freshwater bream Oreochromis mossambicus were evaluated.
• 2.2. Plasma Ca²⁺, Na⁺ and K⁺ concentrations and the osmotic pressure of the blood were monitored over a period of 7 days.
• 3.3. The results showed that the different electrolytes respond differently to the different techniques.
• 4.4. Chemical anaesthesia exhibited the least effects on the parameters studied.

     

Body temperature response of young chicks to intraventricular injections of various cations and EGTA

• 1.1. The effect of intraventricular injections of various cations or ethylene glycol bis [β-amino ethyl ether]-N,N,N'N-tetra acetic acid (EGTA) on cloacal body temperature (T_c) of young chicks (Gallus domesticus) was investigated.
• 2.2. K⁺ and Mg²⁺ had no effect on T_c while Mn²⁺ caused a significant decrease.
• 3.3. Na⁺ and EGTA caused a significant increase in T_c.
• 4.4. The control of the set point for body temperature of chicks is similar to that observed in mammals.

     

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.

     

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.

     

Effect of repetitive cortisol and thyroxine injections on chloride cell number and Na+/K+-ATPase activity in gills of freshwater acclimated rainbow trout,Salmo gairdneri

• 1.1. Freshwater nonanadromous rainbow trout, Salmo gairdneri, were injected three times a week with either saline, 10μg cortisol/g, 1.0μg thyroxine/g or 10μg cortisol/g + 1.0μg thyroxine/g during a period of 28 days (12 injections). A separate group was derived as a subgroup from the thyroxine group on day 14 and received Cortisol + thyroxine from day 14 until day 28 (six injections).
• 2.2. Gill chloride cell number and Na⁺/K⁺-ATPase activity increased by cortisol treatment, the changes being significant on days 7 and 14, respectively.
• 3.3. Thyroxine treatment did not affect gill Na⁺/K⁺-ATPase activity or chloride cell number directly. Neither did it modify the stimulatory effect of cortisol on these parameters.
• 4.4. Muscle water decreased in cortisol-treated fish and increased in thyroxine-treated fish, while no changes were observed in the combined hormone groups.
• 5.5. No changes were observed in plasma chloride in any group during the experiment.
• 6.6. The results demonstrate a putative role of cortisol in stimulating hypo-osmoregulatory mechanisms and suggest that thyroxine is without a direct or a supportive effect for cortisol action.

     

Ionic selectivity of excitable neurone membrane: Are there any separate potential-dependent channels for Na+,Ca2+, Mg2+?

• 1.1. The dependence of the action potential overshoot and inward currents on ionic concentration has been studied on both intact and completely isolated neurones of Limnaea stagnalis.
• 2.2. The dependence of action potential on ion concentration in the medium is similar to that of intact ones.
• 3.3. The overshoot dependence on the log of Ca²⁺ Mg²⁺ and Na⁺ concentration in the medium is linear. This and the character of inward current dependence on ion concentration allow us to suppose the existence of separate channels for Ca, Na and Mg ions along which they move under the action of their own electrochemical potentials. Conductance of these channels depends slightly on ionic concentration in the medium.
• 4.4. If the medium contains both Ca and Sr ions the overshoot dependence on the log of their concentration is of a non-linear character. This indicates that both these kinds of ions pass through the same channel.
• 5.5. A physiological role of different ion mechanisms of action potential generation is discussed.

     

Crayfish retinular cells: Influence of extracellular sodium and calcium upon receptor potential

• 1.1. In crayfish, light stimulation of the retinular cells induces a depolarizing receptor potential.
• 2.2. Experiments were designed to determine the role of Na⁺ and Ca²⁺ on receptor potential during dark And light states.
• 3.3. Depolarization depends on Na⁺ and Ca²⁺ availability to the retinular cell.
• 4.4. Repolarization velocity and response duration depend on extracellular Ca²⁺ availability.
• 5.5. Light adaptation increases receptor potential dependence on calcium and sodium ions.
• 6.6. We analyse these results with respect to other invertebrate photoreceptors.

     

The exchange of radioactive cations by somatic and cardiac muscles of the crayfish

• 1.1. Intracellular concentrations of Na⁺, K⁺, Ca²⁺ and Mg²⁺ were measured in a somatic muscle and in the heart of the crayfish. The uptake and the efflux of Na²⁴, K⁴², Ca⁴⁵ and of Sr⁸⁹ were also measured.
• 2.2. The initial influx rates of the ions from van Harreveld's solution into resting somatic muscle (in μEq/g cell water/hr) are: K⁺ = 25; Na⁺ = 56; Ca²⁺ = 38. Similar figures were obtained for the heart muscle.
• 3.3. The calculated permeability constants (× 10⁸ cm/sec) are: P_K = 64; P_Na = 30 P_Ca = 10; P_Sr = 1·5.
• 4.4. The stimulation of the muscle fiber leads to an additional Ca²⁺ influx of about 2·8 pEq/cm² fiber surface. The additional Ca²⁺ uptake is sufficient to account for the change in potential on the membrane.
• 5.5. When muscles were immersed in Sr²⁺ solutions, no additional Sr⁸⁹ uptake was found with stimulation. However, there is a high resting Sr⁸⁹ uptake and the muscle in Sr²⁺ has a long refractory period, so a reasonable increase in Sr⁸⁹ uptake would not be detectable.
• 6.6. The results are discussed in relation to the divalent cation mechanism for generating action potentials and to the part played by Ca²⁺ in triggering contraction.

     

Alkaline phosphatase from Basidiobolus haptosporosus: Comparison with alkaline phosphatases from rainbow lizard and man

• 1.1. DEAE-cellulose chromatography of mycelial alkaline phosphatase (orthophosphoric monoester phosphohydrolase, EC 3.1.3.1) from Basidiobolus haptosporosus, produced three iso-enzymes “A”, “B” and “C”.
• 2.2. Fraction “A” was further characterized and showed maximum activity at pH 10 in 0.1 M sodium carbonate-bicarbonate buffer.
• 3.3. The enzyme was stimulated by Mg²⁺, Co²⁺ and Mn²⁺ and inactivated by Zn²⁺, Cu²⁺, EDTA, citrate and tartrate.
• 4.4. Phosphate ions inhibited it competitively, phenylalanine uncompetitively and urea noncompetitively.
• 5.5. It was heat stable for 60 min at 37°C but labile above 55°C.
• 6.6. Its K_m with p-nitrophenylphosphate was 0.5 mM; its estimated molecular weight was 160,000.
• 7.7. The results are compared with the properties of alkaline phosphatases from the rainbow lizard and man and discussed in terms of a triadic association between the fungus, the lizard and man.