Inhibition of erythrocyte membrane ATPases with antisickling and anaesthetic substances and ionophoric antibiotics

Phytomedicines and nutraceuticals: alternative therapeutics for sickle cell anemia

Sickle cell anemia is a genetically inherited disease in which the "SS" individual possesses an abnormal beta globin gene. A single base substitution in the gene encoding the human β -globin subunit results in replacement of β 6 glutamic acid by valine, leading to the devastating clinical manifestations of sickle cell disease. This substitution causes drastic reduction in the solubility of sickle cell hemoglobin (HbS) when deoxygenated. Under these conditions, the HbS molecules polymerize to form long crystalline intracellular mass of fibers which are responsible for the deformation of the biconcave disc shaped erythrocyte into a sickle shape. First-line clinical management of sickle cell anemia include, use of hydroxyurea, folic acid, amino acids supplementation, penicillinprophylaxis, and antimalarial prophylaxis to manage the condition and blood transfusions to stabilize the patient's hemoglobin level. These are quite expensive and have attendant risk factors. However, a bright ray of hope involving research into antisickling properties of medicinal plants has been rewarding. This alternative therapy using phytomedicines has proven to not only reduce crisis but also reverse sickling (in vitro). The immense benefits of phytomedicines and nutraceuticals used in the management of sickle cell anemia are discussed in this paper.

A study of the perturbation effects of the local anesthetic procaine on human erythrocyte and model membranes and of modifications of the sodium transport in toad skin

The interaction of the local anesthetic procaine with human erythrocytes, isolated unsealed human erythrocyte membranes (IUM), isolated toad skins, and molecular models is described. The latter consisted of phospholipid multilayers built-up of dimyristoylphosphatidylcholine (DMPC) and of dimyristoylphosphatidylethanolamine (DMPE), representatives of phospholipid classes located in the outer and inner monolayers of the human erythrocyte membrane, respectively. Optical and scanning electron microscopy of human erythrocytes revealed that procaine induced the formation of stomatocytes. Experiments performed on IUM at 37 degrees C by fluorescence spectroscopy showed that procaine interacted with the phospholipid bilayer polar groups but not with the hydrophobic acyl chains. X-ray diffraction indicated that procaine perturbed DMPC structure to a higher extent when compared with DMPE, its polar head region being more affected. Electrophysiological measurements disclosed a significant decrease in the potential difference (PD) and in the short-circuit current (Isc) after the application of procaine to isolated toad skin, reflecting inhibition of active ion transport.

Structural effects of the local anesthetic bupivacaine hydrochloride on the human erythrocyte membrane and molecular models

The interaction of the local anesthetic bupivacaine with the human erythrocyte membrane and molecular models is described. The latter consisted of isolated unsealed human erythrocyte membranes (IUM), large unilamellar vesicles (LUV) of dimyristoylphosphatidylcholine (DMPC), and phospholipid multilayers built-up of DMPC and dimyristoylphosphatidylethanolamine (DMPE), representatives of phospholipid classes located in the outer and inner monolayers of the human erythrocyte membrane, respectively. Optical and scanning electron microscopy revealed that bupivacaine induced erythrocyte spheroechinocytosis. According to the bilayer couple hypothesis, this result implied that bupivacaine inserted in the outer monolayer of the erythrocyte membrane. Experiments performed on IUM and DMPC LUV by fluorescence spectroscopy and X-ray diffraction on DMPC and DMPE multilayers confirmed this result. Changes in the molecular organization of membranes alter lipid-protein interactions and induce functional perturbation of membrane proteins such as Na(+) channels. Since local anesthetics may control the influx of Na(+) into the human erythrocyte, in order to relate the structural perturbations induced by bupivacaine in these systems to Na(+) transport, the interaction of this anesthetic with isolated toad skin was also studied. Electrophysiological measurements indicated a significant decrease in the potential difference and in the short-circuit current of the skin after the application of the anesthetic, reflecting inhibition of the active transport of ions. These results suggest that bupivacaine-induced conformational changes of the lipid molecules alter the lipid-protein boundaries of the outer moiety of the erythrocyte membrane, thus interfering with the function of neighboring sodium channels.