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Cellular and humoral effects of naftopidil in man
1Department of Pathophysiology, University of Leuven, Belgium.
Abstract:
The effects of naftopidil on the intracellular concentration and transmembrane fluxes of Na+ and K+ in erythrocytes and on the intracellular Na+, K+ and free cytosolic Ca2+ concentration in platelets were studied in twenty-four normal male subjects, using a double-blind study design. After a run-in period on placebo for 1 week, the subjects were treated with either placebo (n = 8) or naftopidil 25 mg (n = 8) or 50 mg (n = 8) once a day for 4 weeks. Intraerythrocyte Na+ concentration and the erythrocyte anion carrier were decreased during naftopidil administration. No significant effect of naftopidil could be demonstrated on ouabain-sensitive Na+ efflux, bumetanide-sensitive Na+ efflux, ouabain, bumetanide-resistant Na+ and K+ efflux and Na+, Li(+)-countertransport activity in red blood cells or on the intraerythrocyte K+ and Mg2+ concentration. The free cytosolic Ca2+ and Na+ concentration in platelets was also decreased during naftopidil administration while no effect of naftopidil was found on the intracellular K+ and Mg2+ concentration in platelets.
Insights
Naftopidil treatment reduced intracellular sodium (Na+) and calcium (Ca2+) concentrations in erythrocytes and platelets. This study investigated naftopidil
Area of Science:
- Pharmacology
- Cell Physiology
- Cardiovascular Research
Background:
- Intracellular ion concentrations, particularly sodium (Na+) and potassium (K+), are critical for erythrocyte and platelet function.
- Dysregulation of ion transport can contribute to various cardiovascular conditions.
- Naftopidil is an alpha-1 adrenergic receptor antagonist with potential effects on ion homeostasis.
Purpose of the Study:
- To investigate the effects of naftopidil on intracellular Na+, K+, and Ca2+ concentrations in human erythrocytes and platelets.
- To assess the impact of naftopidil on transmembrane ion fluxes in red blood cells.
Main Methods:
- A double-blind, placebo-controlled study involving 24 healthy male subjects.
- Subjects received either placebo, 25 mg, or 50 mg of naftopidil daily for 4 weeks.
- Measurements included intraerythrocyte ion concentrations, erythrocyte anion carrier activity, and platelet cytosolic ion concentrations.
Main Results:
- Naftopidil administration led to decreased intraerythrocyte Na+ concentration and erythrocyte anion carrier activity.
- Platelet free cytosolic Ca2+ and Na+ concentrations were significantly reduced by naftopidil.
- No significant effects of naftopidil were observed on erythrocyte K+ and Mg2+ concentrations or various Na+ and K+ efflux pathways.
Conclusions:
- Naftopidil influences intracellular Na+ and Ca2+ levels in erythrocytes and platelets.
- The findings suggest a potential role for naftopidil in modulating cellular ion transport mechanisms.
- Further research is warranted to explore the clinical implications of these observed effects.