calcimycin and nonactin

The interactions of carrier ionophores, nonactin, A23187, and lasalocid A with liposomes formed from the synthetic lipids dimyristoylphosphatidylcholine and dipalmitoylphosphatidylcholine are investigated by differential scanning calorimetry and 1H and 31P nuclear magnetic resonance techniques. The results indicate that the mode of interaction of these ionophores is dependent on the fluidity of the bilayer and on the chemical nature of these ionophores. The 31P NMR studies are suggestive of the formation of small particles that are probably intervesicular lipid-ionophore aggregates in multilamellar vesicles when they are incorporated with these ionophores at high concentrations. The results are interpreted on the basis of the chemical structure and conformations of the ionophores in membrane mimetic media. The 1H NMR line-width measurements indicate that the aromatic rings containing the carboxyl groups of lasalocid A and A23187 are located near the membrane interface while the rest of the molecule is buried in the membrane interior.

Topics: 1,2-Dipalmitoylphosphatidylcholine; Anti-Bacterial Agents; Calcimycin; Calorimetry, Differential Scanning; Dimyristoylphosphatidylcholine; Lasalocid; Lipid Bilayers; Macrolides; Magnetic Resonance Spectroscopy; Membrane Fluidity; Models, Biological; Molecular Conformation; Valinomycin

The inhibitory effect of five ionophores, namely, A23187, nonactin, nigericin, monensin and m-chlorocarbonyl cyanide phenylhydrazone, on human sperm motility were measured with a trans-membrane migration method. The concentrations of A23187 and nigericin that decreased sperm motility to 50% of control were 20 microM (10.5 mg/l) and 8 microM (5.8 mg/l), respectively. Because these two ionophores were more potent than previously reported membrane-active sperm-immobilizing agents, we propose that ionophores could be a new category of vaginal contraceptive if a pharmaceutical preparation that is safe to be administered in vivo can be developed.

Topics: Anti-Bacterial Agents; Calcimycin; Carbonyl Cyanide m-Chlorophenyl Hydrazone; Contraceptive Agents, Female; Humans; Ionophores; Macrolides; Male; Monensin; Nigericin; Sperm Motility

Peripheral models using blood cells might be biochemical markers in various psychiatric illnesses. In previous papers we reported a deficit of tyrosine and tryptophan transport in red cells incubated in plasma from depressed patients. In the present study we investigated the role played by sodium and calcium in these transports by using inhibitors and ionophores of the main movements of these electrolytes. We also studied the contribution of phloretin-sensitive countertransport, which has been described as low in psychiatric conditions.

Topics: 4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; 4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; Alkaloids; Anti-Bacterial Agents; Benzophenanthridines; Biological Transport; Calcimycin; Calcium; Erythrocyte Membrane; Female; Furosemide; Humans; In Vitro Techniques; Ionophores; Isoquinolines; Lanthanum; Macrolides; Male; Phloretin; Sodium; Tryptophan; Tyrosine

Topics: Animals; Anti-Bacterial Agents; Calcimycin; Chromosomes; Dinitrophenols; Drosophila melanogaster; Hot Temperature; Hydrogen-Ion Concentration; Macrolides; Membrane Potentials; Potassium; Salivary Glands