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Biomedical subjects

M Bornancin

Publications and source records attributed to M Bornancin.

At least 19 recordsLinked to original sources
PubMed1991

Measurement of branchial vascular space of trout, Oncorhynchus mykiss: effects of adrenaline.

Using the isolated-perfused head preparation at a constant flow rate, hemodynamic effects of adrenaline were studied in trout gills. The calculation of the vascular spaces was performed with the isotopic pulse technique allowing measurement of the distribution space of the tracer. The results show that the branchial arterial circuit was cleared more quickly than the branchial venous and cephalic circuits. Adrenaline addition significantly increased the volume of the branchial arterial circuit at the expense of the venous circuit, illustrating the closing of arterio-venous sphincters under catecholamine control. The increase of the arterial volume could be explained by a vasodilation of the arterial circuit, rather than resulting from lamellar recruitment. Furthermore, the flow rate of the cephalic circuit represented 5% of the total branchial flow rate.

Animals↗
PubMed1991

Kinetics of potassium transport across trout gills.

1. Kinetics of potassium transport across trout gills was studied, using an isolated-head preparation. 2. Potassium exchanges were shown to take place across secondary lamellae only. 3. Influx of potassium was saturable and fitted satisfactorily the lineweaver-Burk linear plot. 4. Results suggest that these exchanges occur through potassium channel. 5. Kinetics of potassium exchanges is discussed in relation to the maintenance of the osmoregulation in fish.

Animals↗
PubMed1987

The effects of starvation and sexual maturation on Na+ transbranchial fluxes following direct transfer from fresh water to sea-water in rainbow trout (Salmo gairdneri).

1. The perfused isolated head technique has been used to measure sodium arterial fluxes following direct transfer from fresh water to sea-water. 2. A starvation-related decrease in net sodium flux is reported. 3. Sexual maturation slackens the decrement of this net flux. 4. In starved fish, the cytological modifications of chloride cells following such a transfer are delayed. 5. This effect of starvation is discussed in terms of lamella sodium imperviousness.

Animals↗
PubMed1985

Estimation of sodium uptake through the gill of the rainbow trout Salmo gairdneri.

Sodium exchanges through the gill epithelia were estimated in the rainbow trout, Salmo gairdneri, using the perfused head technique. The head tissues accumulate radioactivity. In addition there exists an extrabranchial entry of sodium, which is 20 times smaller than the branchial one. The study of the evolution of venous and arterial sodium specific activities as a function of time is necessary before flux measurements are achieved. Contrary to previous studies, an uptake at the primary lamella level is demonstrated. Uptake of sodium through the secondary lamellae can be measured rapidly while at least 30 min are needed for measurement of uptake through the primary lamellae. Chloride cells of the primary lamellae contribute to about 20% of the total sodium uptake.

Animals↗
PubMed1983

Extraintestinal calcium uptake in the killifish, Fundulus heteroclitus.

Extraintestinal calcium influxes were measured in the killifish, Fundulus heteroclitus, in solutions with different calcium concentrations, from distilled water level (near 0) to seawater level (approximately 12 mM). The extraintestinal influx is modified by the concentration of calcium in the medium during the adaptive period. In freshwater-adapted fish, calcium depletion resulted in an increase in calcium uptake. Such an adaptation was not observed in calcium-depleted fish in artificial calcium-deficient seawater. Calcium depletion in either medium seems to increase the calcium permeability. No correlation was found between Ca-ATPase activity in the gill tissue and calcium uptake.

Adaptation, Physiological↗
PubMed1981

Cl- -HCO3- dependent ATPase in gills of freshwater and seawater adapted eels (Anguilla anguilla L.).

The gills of both seawater and freshwater adapted eels have an ATPase activity which is stimulated by anions in the presence of Mg2+. Plasma membranes were distinguished from mitochondrial membranes with specific enzyme markers, the membrane fractions separated on a discontinuous sucrose gradient, and the ATPase activity of the plasma membranes studied. Activation by the anions of Cl- or HCO3- followed Michaelis-Menten kinetics and was competitively inhibited by SCN-. The Cl- and HCO3- activation characteristics were determined: no differences between the plasma membrane ATPase activities of freshwater and seawater-adapted fishes were observed. Maximal activity measurements after solubilization of the enzymes by Triton X 100 confirmed these findings. The function of a membrane anion-dependent ATPase in the brachial epithelium of euryhaline fish is discussed.

Adenosine Triphosphatases↗
PubMed1980

Cl--HCO3--ATPase in gills of the rainbow trout: evidence for its microsomal localization.

The intracellular localization of a Cl--HCO3--ATPase, which is inhibited by SCN-, was studied in the gills of the rainbow trout, Salmo gairdneri. This activity can be measured in the absence of contamination by mitochondria (i.e., in the absence of succinate dehydrogenase or cytochrome c oxidase activities). The distribution of the 5'-nucleotidase and of the ATPase stimulated by Cl- and HCO3- after sucrose density gradient centrifugation of the microsomal fraction was compared. Because those activities cannot be separated, it is postulated that the anion-stimulated ATPase is located in the plasma membrane. The activation of this microsomal anion ATPase by chloride has been studied extensively. The possible role of the Cl--HCO3--ATPase of trout gills in the Cl-/HCO3- exchange and in the regulation of the internal acid-base balance is discussed.

Adenosine Triphosphatases↗
PubMed1977

A Cl-/HCO-3-ATPase in the gills of Carassius auratus. Its inhibition by thiocyanate.

An ATPase is demonstrated in plasma membrane fractions of goldfish gills. This enzyme is stimulated by Cl- and HCO-3, inhibited by SCN-. Biochemical characterization shows that HCO-3 stimulation (Km = 2.5 mequiv./l) is specifically inhibited in a competitive fashion by SCN- (Ki = 0.25 mequiv./l). This residual Mg2+-dependent activity is weakly affected by SCN-. In the microsomal fraction chloride stimulation of the enzyme occurs in the presence of HCO-3 (Km for chloride = 1 mequiv/l); no stimulation is observed in the absence of HCO-3. Thiocyanate exhibits a mixed type of inhibition (Ki = 0.06 mequiv./l) towards the Cl- stimulation of the enzyme. Bicarbonate-dependent ATPase from the mitochondrial fraction is stimulated by Cl-, but this enzyme has a relatively weak affinity for this substrate (Km = 14 mequiv./l).

Adenosine Triphosphatases↗
PubMed1975

Environmental salinity and sodium and chloride exchanges across the gill of Tilapia mossambica.

10 Freshwater-(FW)-adapted, one-third seawater (1/3 SW)-adapted and seawater (SW) adapted Tilapia mossambica were compared for their branchial Na+ influx and efflux as well as Cl- efflux. Na+ and Cl- effluxes were identical. Rates of effluxes were in 1/3 SW- and in SW-adapted fish 10 times and 200 times higher respectively than in FW specimens. 20 Shock due to handling and transfer to small experimental chambers induced, within 20 to 45 min., a considerable increase in Na+ efflux and a more discrete augmentation of the Na+ influx. 30 Branchial Mg++-and Na+-K+ activated ATPase activities increased significantly upon adaptation from FW to 1/3 SW. No significant increase was apparent upon adaptation from 1/3 SW to SW. 40 The trans-branchial potential observed in SW Tilapia resembled the pattern previously described in other species of teleosts.

Adaptation, Physiological↗
PubMed1972

The effects of calcium on branchial sodium fluxes in the sea-water adapted eel, Anguilla anguilla, L.

1. The sodium influx through the gills of eels placed in calcium-free sea water for 15 hr was double that of controls. The effect was reversed in 1 hr by addition of calcium.2. The total sodium outflux through the gills of fish placed in calcium-free sea water for 15 hr was double that of controls. The effect was only partially reversed in 15 hr by addition of calcium.3. The passive outflux component of the total outflux was increased fourfold when calcium was removed and was restored to normal in 15 hr by addition of calcium. The active (exchange) outflux component of the total outflux was halved by calcium removal and increased above normal following calcium addition.4. The inability of calcium to restore the total outflux to normal within 15 hr in calcium-depleted fish, together with the raised plasma sodium concentration at this time, suggests that the raised outflux is caused by homoeostatic mechanisms, rather than permeability changes in the gill epithelium.

Adaptation, Physiological↗