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Biomedical subjects

G Mujica

Publications and source records attributed to G Mujica.

5 recordsLinked to original sources
PubMed2000

Neonatal red blood cells: amiloride-insensitive Na+-H+ transport isoform would express Na+-Li+ exchange.

Neonatal red cells (umbilical cord blood) were in vitro incubated in isotonic media (thiocyanate as predominant anion). This experimental condition was selected as it was known that this chaotropic anion induced activation of Na+-H+ exchange. The transport amiloride-sensitive mechanism, that decreased the acidic intracellular pH change occurring in this medium, would correspond to Na+-H+ exchange (NHE1 isoform). However, the Na+-Li+ exchange, also determined in the cells in the above-mentioned medium was not affected by amiloride. The present data suggest that an amiloride insensitive Na+-H+ exchange isoform would express Na+-Li+ countertransport in these cells.

Amiloride↗
PubMed2000

Na+/Li+ exchange kinetic characterization. Red blood cells from normotensive individuals.

The plasma membrane Na+/Li+ exchange is of research interest because it is involved in some pathologic states. A kinetic analysis of this transport system would be of greater importance as compared to the flux determination under "standard" conditions (reactants saturating levels) as a way to define normal values. Unidirectional lithium fluxes in red blood cells from normal adults were determined as a function of "trans" (contralateral) sodium ion concentration. Relating Li+ efflux and influx (Na+ "trans") kinetic parameters we found free carrier reorientation between the two phases (asymmetry).

Cations, Monovalent↗
PubMed1996

Human red cells from prenatal stages of hemopoiesis. Lithium flux components.

Red cells from umbilical cord with increased lithium content were submitted to different experimental conditions in order to study lithium flux components. There appeared three components: First, an ouabain-sensitive component, related to Na+ replacement with Li+ in the primary active Na+/K+ transport system. The magnitude of this fraction is greater than in adults' red cells. Second, an outside sodium-dependent Li+ efflux fraction, corresponding to the Li+/Na+ countertransport system with Vmax and K(m) values of 0.1 (mmol/l cells.h) and 2.58 (mmol/l), respectively. The Na+o-affinity for lithium efflux in this system is greater in neonatal than in adults' red cells. Third, a leak fraction with an equal value to that reported in adults' red cells. Furthermore, the possible non-existence of a bumetanide-sensitive lithium flux fraction was shown in neonatal red cells.

Adult↗
PubMed1984

Incorporation of phospholipids in Ehrlich ascites tumor cells.

Ehrlich ascites tumor cells (EATC) were incubated with unilamellar vesicles (UV) or multilamellar vesicles (MV). UV and MV were incorporated differently into EATC. The increase in 32P-phospholipid in EATC in the presence of UV was 12% in 300 min. Absorption of phospholipid from MV could account for only 3%. About 50% of the UV incorporation of 32P was by endocytosis and/or fusion.

Animals↗