Changes in erythrocyte morphology induced by imipramine and chlorpromazine

Erythrocytes as model cells for biocompatibility assessment, cytotoxicity screening of xenobiotics and drug delivery

Erythrocytes (RBCs) represent the main cell component in circulation and recently have become a topic of intensive scientific interest. The relevance of erythrocytes as a model for cytotoxicity screening of xenobiotics is under the spotlight of this review. Erythrocytes constitute a fundamental cellular model to study potential interactions with blood components of manifold novel polymer or biomaterials. Morphological changes, subsequent disruption of RBC membrane integrity, and hemolysis could be used to determine the cytotoxicity of various compounds. Erythrocytes undergo a programmed death (eryptosis) which could serve as a good model for evaluating certain mechanisms which correspond to apoptosis taking place in nucleated cells. Importantly, erythrocytes can be successfully used as a valuable cellular model in examination of oxidative stress generated by certain diseases or multiple xenobiotics since red cells are subjected to permanent oxidative stress. Additionally, the antioxidant capacity of erythrocytes, and the activity of anti-oxidative enzymes could reflect reactive oxygen species (ROS) generating properties of various substances and allow to determine their effects on tissues. The last part of this review presents the latest findings on the possible application of RBCs as drug delivery systems (DDS). In conclusion, all these findings make erythrocytes highly valuable cells for in vitro biocompatibility assessment, cytotoxicity screening of a wide variety of substances as well as drug delivery.

Detergent effects on membranes at subsolubilizing concentrations: transmembrane lipid motion, bilayer permeabilization, and vesicle lysis/reassembly are independent phenomena

Soluble amphiphiles, or detergents, are known to produce a number of structural and dynamic effects on membranes, even at concentrations below those causing membrane solubilization (i.e. in the so-called stage I of detergent-membrane interaction). The main subsolubilizing detergent effects on membranes are transmembrane lipid motion (flip-flop), breakdown of the membrane permeability barrier (leakage), and vesicle lysis/reassembly. For a proper understanding of membrane solubilization by detergents, it is important to assess whether the various effects seen at subsolubilizing surfactant concentrations occur independently from each other or are interconnected by cause-effect relationships so that they can be interpreted as necessary steps in the overall process of solubilization. To answer this question, we have explored the three above-mentioned effects (i.e., flip-flop, leakage, and lysis/reassembly) apart from solubilization in model (large unilamellar vesicles) and cell (erythrocyte) membranes. Five structurally different surfactants, namely, chlorpromazine, imipramine, Triton X-100, sodium dodecylsulfate, and sodium deoxycholate have been used. Each of them behaves in a unique way. Our results reveal that lipid flip-flop, vesicle leakage, and vesicle lysis/reassembly occur independently between them and with respect to bilayer solubilization so that they cannot be considered to be necessary parts of a higher-order unified process of membrane solubilization by detergents.

Kinetics membrane disruption due to drug interactions of chlorpromazine hydrochloride

Drug-membrane interactions assume considerable importance in pharmacokinetics and drug metabolism. Here, we present the interaction of chlorpromazine hydrochloride (CPZ) with supported phospholipid bilayers. It was demonstrated that CPZ binds rapidly to phospholipid bilayers, disturbing the molecular ordering of the phospholipids. These interactions were observed to follow first order kinetics, with an activation energy of approximately 420 kJ mol(-1). Time-dependent membrane disruption was also observed for the interaction with CPZ, such that holes appeared in the phospholipid bilayer after the interaction of CPZ. For this process of membrane disruption, "lag-burst" kinetics was demonstrated.