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Biomedical subjects

P Pic

Publications and source records attributed to P Pic.

33 records · Page 2Linked to original sources
PubMed1977

[Origin of ammonia excreted by trout gill (Salmo gairdneri)].

In the perfused head of Trout the gills are the site of ammonia clearance which corresponds exactly to the appearance rate of ammonia in the external medium. Thus metabolic production of ammonia by the gill apparently does not participate to its excretion. Under ammonia-free Ringer perfusion however, endogenous production is observed and ammonia is excreted in both external and internal media.

Ammonia↗
PubMed1977

Microtubules in the "chloride cell" of the gill and disruptive effects of colchicine on the salt balance of the sea water adapted Mugil capito.

Electron-microscopic examination of the gill of the grey mullet, Mugil capito adapted to sea water, reveals the presence of numerous microtubules in the apical region of the mitochondria-rich cells. No microtubules are found in other types of epithelial cell. Exposure of the fish to colchicine (10(-4)M) for four hours induces a 20% increase of plasma Na and Cl. Colchicine leaves the water permeability of the gill unchanged but Cl and Na exchange fluxes are inhibited by 30-50% and the gill potential pattern is altered. Salt gain replaces salt excretion across the gill. The K dependent Na and Cl efflux components, independent of the gill potential shift produced by K, are totally inhibited by colchicine. Exposure to lumicolchicine is not followed by a significant change of these Na and Cl efflux-components and potential pattern. The possibility that microtubules intervene in the salt excretion process across the chloride cells is discussed.

Adaptation, Physiological↗
PubMed1975

Branchial effects of epinephrine in the seawater-adapted mullet. II. Na+ and Cl- extrusion.

Injection of epinephrine into Mugil capito adapted to seawater is followed by a 40-60% inhibition of the Na and Cl effluxes. Simultaneously the Na influx is decreased by 30%, the overall result being a reduction of the net sodium extrusion rate by the gill. The change in Na influx is in part explained by a 75-80% decrease of the oral ingestion of seawater. This branchial adrenergic response is sensitive to alpha-blockade by phentolamine and tolazoline and insensitive to beta-blockade by propranolol. Both alpha-blockers are ineffective when injected alone. Propranolol injected alone mimics epinephrine while simultaneous injection of phentolamine blocks the response to propranolol. Rapid transfer experiments suggest that epinephrine inhibits the branchial Cl pump and its associated Na/K exchange mechanism. The leak pathway for these ions remains insensitive to epinephrine.

Adaptation, Physiological↗
PubMed1973

Adrenoceptors and adenyl cyclase in gills.

The content of cyclic 3',5'-adenosine monophosphate (cAMP) in the gills of the mullet (Mugil capito) has been measured. The basal level was found to be 2.9+/-0.3 pmol/mg wet weight. When fish were first anaesthetized with MS222 (tricaine) and the gills perfused to remove blood, the concentration of cAMP was raised to 14.3+/-1.9 pmol/mg wet weight.Adrenaline caused a significant increase in cAMP content, an effect that was blocked by propranalol, a beta-adrenoceptor antagonist. In the presence of the alpha-adrenoceptor block- ing agent phentolamine, adrenaline still caused an increase in nucleotide content.The results are discussed in relation to adrenaline and the adenyl cyclase system.

Adenylyl Cyclases↗
PubMedDate not supplied

Two fetal hemoglobin variants affecting the same residue: Hb F-Emirates [G gamma 59(E3)Lys-->Glu] and Hb F-Sacromonte [G gamma 59(E3)Lys-->Gln].

Two fast-moving fetal hemoglobin variants were discovered in hematologically normal newborn babies; the first originated in the United Arab Emirates and the second in France. The structural study, carried out by miniaturized techniques of protein chemistry, showed that these two mutations affected the same residue of the G gamma chain, the lysine at position 59(E3) was replaced by glutamic acid in Hb F-Emirates, and by glutamine in Hb F-Sacromonte.

Amino Acid Sequence↗