Hemolymph Chloride Concentration Research Articles

Environmental hypoxia affects osmotic and ionic regulation in freshwater midge-larvae

The effect of anaerobic metabolism on the osmotic and ionic regulation of the extracellular fluid was examined. Larvae of three species, characterized by different hypoxia tolerance, were studied: Chaoborus crystallinus, Culex pipiens and Chironomus gr. plumosus. The use of the capillary electrophoresis technique made it possible to determine approximately 15 different ions from individual hemolymph samples. The hemolymph concentration of both inorganic and organic anions and cations as well as the osmolality were measured. A correlation between the hypoxia tolerance and the capability to avoid net changes in the ion concentration or in the osmolality of the three species studied here is proposed: Culex larvae, which have the lowest hypoxia tolerance, show a very large and very rapid lactate accumulation in their hemolymph under experimental hypoxia. This lactate accumulation is not compensated for by a change in the concentration of any other ion. Chaoborus larvae, with a medium hypoxia tolerance, utilize their very large hemolymph malate pool as a source of anaerobic energy. It is converted into succinate, thus inducing little net changes in the sum of the anions. There is a marked increase of the hemolymph osmolality, though. Chironomus larvae have the highest hypoxia tolerance and there are remarkably little changes in their hemolymph under hypoxia. Although these larvae are described as relying mainly on ethanol fermentation under environmental anaerobiosis, we demonstrated a marked lactate fermentation in severe hypoxia. The lactate accumulation observed in our study was compensated by a concomittant decrease of the hemolymph chloride concentration.

Responses of osmotic and chloride concentrations of Penaeus chinensis Osbeck subadults acclimated to different salinity and temperature levels

Hemolymph osmolality, chloride concentration and tissue water of Penaeus chinensis Osbeck subadults (16.40 ± 2.82 g) were determined after they were acclimated from 33 ppt to 10, 20, 30 and 40 ppt for 14 days at 24 °C, and then acclimated to 12, 18, 24 and 30 °C for 14 days. Hemolymph osmolality and chloride concentration increased with increased salinity, but decreased with increased temperature. Tissue water decreased with increased salinity. Hemolymph osmolality and chloride concentration were linearly related to medium osmolality and medium chloride concentration, respectively. The isosmotic point and isoionic point was 837, 811, 735, 707 mOsm/kg and 324, 299, 289, 278 mEq Cl −/l which was equivalent to 28.4, 27.5, 25.0, 24.1 ppt and 19.6, 18.1, 17.5, 16.9 ppt for shrimp acclimated to 12, 18, 24, 30 °C, respectively. Hemolymph chloride concentration increased with increased hemolymph osmolality, whereas tissue water decreased with increased hemolymph osmolality. Penaeus chinensis subadults at 24 and 30 °C had superior osmoregulation, and accepted less change of tissue water and hemolymph osmolality than those at 12 and 18 °C due to changes of salinity and temperature.

Changes in gill ultrastructure and haemolymph chloride concentrations in the crayfish, Astacus astacus, exposed to de-acidified aluminium-rich water

Individuals of the crayfish, Astacus astacus, exposed to aluminium-rich, de-acidified water in a crayfish farm (acid-reactive aluminium fraction 180 μg All −1, labile aluminium fraction 20 μg All −1, pH 6.7) showed symptoms such as bulging of the integument between the carapace and the abdomen, and browning of the gills, generally followed by death in the pre-molt or molting stages. Exposed individuals had a significant decrease (≈35%) in haemolymph chloride concentrations compared to unexposed control individuals. Examination of the gills by transmission electron microscopy (TEM) revealed severe morphological changes in gill epithelia and underlying tissue. By X-ray microanalysis a pronounced accumulation of aluminium was detected on the gill surface of exposed specimens. This aluminium probably interferred with the normal ion-exchange mechanisms and led to crayfish death.

Osmotic and chloride regulation in the hemolymph of the tiger prawn Penaeus monodon during molting in various salinities

The effect of molting on osmotic and chloride concentrations in the blood of the prawn Penaeus monodon Fabricius (20±3 g) at various salinities was investigated. Prawns were obtained from ponds in Iloilo, Philippines, in 1984. They were stocked in salinities of 8, 20, 32 and 44‰, and their hemolymph was sampled during molt (Time 0), and then 0.125, 0.25, 0.5, 1, 2, 4, 6, 10 and 14 d after molting. Prawns during and immediately after molt tended to conform to the environmental osmolality. Subsequent postmolt (≧0.5 d) stages displayed more divergence from external salinity. The isosmotic point was higher (940±30 mOsm kg-1) during molt than during intermolt (663±8 mOsm/kg-1), suggesting different osmotic requirements in early molt. Hyperregulation of hemolymph chloride below 20‰ S, as well as isoionic point (301±6 mM), were independent of molting stage. At 20‰ S and above, newly molted (0 to 0.25 d post-molt) individuals tended to conform to the external chloride concentration while intermolt (≧0.5 d) post-molt individuals did not. Contribution of hemolymph chloride to hemolymph osmolality was greater during intermolt than during ecdysis, suggesting an important role for other negatively charged ions during molt. When molt occurred in 20‰ S (the test salinity most similar to the isoionic salinity), there was little or no change in hemolymph osmolality or chloride concentration from 0 to 14 d postmolt. At 8, 32 and 44‰ S, the change from molt to intermolt values in hemolymph osmotic and chloride concentrations was hyperbolic. Non-linear least-squares regression showed that prawns generally achieved intermolt values within 1 d after molting. Prawns at intermolt regulated hemolymph osmolality (620 to 820 mOsm kg-1) and chloride concentration (300 to 450 mM) at a much narrower range than during molt (520 to 1 170 mOsm kg-1 and 250 to 520 mM, respectively). Hemolymph osmolality was a more sensitive indicator of physiological response than hemolymph chloride concentration. Distribution and culture of P. monodon might be limited in low salinities by its ability to maintain a hemolymph osmolality ≧500 mOsm kg-1 during molt and ≧600 mOsm kg-1 in intermolt, and in high salinities by its capacity to reduce the hemolymph osmolality from values at molt to those in intermolt. Osmotic and chloride concentrations in the blood of P. monodon clearly varied with both molt stage and salinity of the medium. Dependence on external factors, however, gradually declined in older molt stages, suggesting a reduction in integument permeability and greater development of ion absorption/secretion mechanisms as the exoskeleton hardened.

Ion and CO₂ Regulation in the Freshwater Water Boatman, Cenocorixa blaisdelli (Hung.) (Hemiptera, Corixidae)

Isolated Malpighian tubules of the freshwater Cenocorixa blaisdelli secrete an alkaline urine following stimulation of fluid flow with cAMP. To determine the importance of this avenue of CO₂ loss for pH and ion regulation, corixids raised in fresh water were compared to those acclimated to alkaline (pH 9.8) conditions, with respect to whole organism ion balance. The high-pH insects exhibited an increase in hemolymph chloride concentration and a reduced rate of drinking. Urinary loss of ions and CO₂ could not balance the higher intake of sodium and CO₂ in the alkaline-acclimated insects, although hemolymph concentrations of these components were not significantly different from those concentrations in insects maintained in fresh water. Isolated Malpighian tubules from the two groups of insects did not exhibit differences in their ability to secrete ions or CO₂. Extrarenal avenues may account for the increased chloride concentration and the constant sodium and CO₂ concentrations. It is suggested that chlori...

Effect of salinity on the osmotic, chloride, total protein and calcium concentrations in the hemolymph of the prawn Peneaus monodon (fabricius)

1. 1. Osmolality and chloride concentrations in the hemolymph of Penaeus monodon became stable 1 day after molting in 32 ppt, while total protein and calcium concentrations remained stable throughout the molting cycle. When intermolt (≥ 36 hr postmolt) animals were transferred from control (32 ppt) to experimental (8–40 ppt) salinities, osmolality, chloride and total protein, but not calcium, concentrations in the hemolymph achieved steady state values 24–48 hr after transfer. 2. 2. The hemolymph osmolality was a linear function (slope = 0.28) of medium osmolality at salinities between 8 and 40 ppt. It was isosmotic to seawater at 698 mOsm (10 g prawns) and 752 mOsm (30 g), and was hyperosmotic to the medium below isosmotic concentrations, and hypoosmotic to those above. 3. 3. Hemolymph chloride concentration was isoionic to seawater at 334 mM, and was hyperregulated below isoionic concentrations, and hyporegulated to those above. 4. 4. P. monodon maintained its hemolymph calcium concentration between 6.4 and 10 mM when medium salinities increased from 8 to 40 ppt. 5. 5. Total protein concentration in the hemolymph was independent of medium salinity (8–40 ppt) and hemolymph osmolality (540–850 mOsm).