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M F Villamil

Publications and source records attributed to M F Villamil.

32 records · Page 2Linked to original sources
PubMed1969

The effect of ouabain and external potassium on the ion transport of rabbit red cells.

Na efflux of rabbit RBC is approximately 10 mmoles/kg wet weight. hr. One-half of this consists of a ouabain-insensitive exchange diffusion component. Ouabain inhibits 2.5 mmoles/kg.hr of Na efflux. K influx is 3.0 mmoles/kg.hr; 2.2 mmoles/kg.hr are inhibited by ouabain. In contrast with human RBC, ouabain inhibition of Na efflux and K influx of rabbit RBC is easily reversible. After 2 hr, ouabain inhibition of Na efflux is completely compensated for by increased internal Na concentration and Na efflux returns to initial levels. Removal of ouabain at this stage results in stimulation of the efflux by 4.3 mmoles/kg.hr. Na influx is initially not affected by ouabain but is increased by 2.4 mmoles/kg.hr after 2 hr incubation with the drug. Removal of K from normal Ringer does not affect Na efflux and increases Na influx by 1.6 mmoles/kg.hr. Addition of ouabain to K-free Ringer inhibits Na efflux and influx to the same extent (1.6 mmoles/kg.hr). Removal of Na from K-free Ringer has an inhibitory effect on efflux similar to that of ouabain. These findings suggest that the fraction of Na efflux inhibited by removal of external K is completely replaced by a new, ouabain-sensitive exchange diffusion of Na ions.

Animals↗
PubMedDate not supplied

Role of extracellular volume expansion in the development of DOC-salt hypertension in the rat.

Changes in inulin space, plasma and blood volume, exchangeable and "noninulin" sodium were studied during the prehypertensive, early and late hypertensive stages of deoxycorticosterone (DOC)-salt administration in the rat. The effect of an acute water load in previously nephrectomized animals was also studied. Hypertension developed after 1 to 2 weeks of the DOC-salt regimen and was always preceded by enlargement of the inulin space and increased plasma and blood volume. Expansion of extracellular fluids receded when blood pressure started to rise but reappeared after 4 to 6 weeks of treatment. Plasma sodium was high only in the hypertensive groups. An acute water load increased blood pressure of normal rats and decreased blood pressure of DOC-salt early hypertensive rats. These findings suggest that extracellular volume expansion inhibits a vasopressor mechanism that involves vasopressin and could be stimulated by hypernatremia.

Animals↗