Biomaterial Database

Calmodulin-mediated effects of loperamide on chloride transport by brush border membrane vesicles from human ileum. 1988

R Stoll, and H Ruppin, and W Domschke

Department of Medicine, University of Erlangen-Nuremberg, Federal Republic of Germany.

We investigated whether the synthetic opiate loperamide-HCl is able to regulate specific transport systems for sodium and chloride in brush border membrane vesicles (BBMVs) from human ileum and whether such activities are mediated by calcium/calmodulin. In BBMVs we studied Na+/H+ antiport, Cl+/OH- antiport, Na+/Cl- cotransport, and the Cl- conductive pathway. Brush border membrane vesicles were incubated with 10 microM loperamide over 4 h at 5 degrees C before the uptake experiments. In ileal BBMVs, loperamide stimulated intravesicular accumulation of Na+ in the presence of Cl- and vice versa. After 1 min of incubation, the stimulatory effect was 35% +/- 5% (p less than 0.005) of the control without loperamide. Loperamide also stimulated Cl-/OH- antiport by 30% +/- 5% (p less than 0.005) in BBMVs of ileum. In addition, we studied the role of Ca2+/calmodulin in the action of loperamide on chloride transport by human BBMVs. In loperamide-pretreated BBMVs, calmodulin activity was significantly decreased (12 +/- 2 vs. 38 +/- 4 pmol/mg protein). When loperamide-pretreated vesicles were incubated with 2 microM calcium (free concentration) plus 5 microM calmodulin for 1 h at 5 degrees C, complete inhibition of the stimulatory effect of loperamide on Cl-/OH- antiport and Na+/Cl- cotransport was observed. Increasing the Ca2+/calmodulin activity of loperamide-pretreated BBMVs with 2 microM calcium plus 5 microM calmodulin led to a significant inhibition of Cl-/OH- antiport and Na+/Cl- cotransport by 40% +/- 5% (p less than 0.005).

UI	MeSH Term	Description	Entries
D007082	Ileum	The distal and narrowest portion of the SMALL INTESTINE, between the JEJUNUM and the ILEOCECAL VALVE of the LARGE INTESTINE.
D008139	Loperamide	One of the long-acting synthetic ANTIDIARRHEALS; it is not significantly absorbed from the gut, and has no effect on the adrenergic system or central nervous system, but may antagonize histamine and interfere with acetylcholine release locally.	Imodium,Loperamide Hydrochloride,Loperamide Monohydrochloride,R-18553,Hydrochloride, Loperamide,Monohydrochloride, Loperamide,R 18553,R18553
D008871	Microvilli	Minute projections of cell membranes which greatly increase the surface area of the cell.	Brush Border,Striated Border,Border, Brush,Border, Striated,Borders, Brush,Borders, Striated,Brush Borders,Microvillus,Striated Borders
D010880	Piperidines	A family of hexahydropyridines.
D002118	Calcium	A basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.	Coagulation Factor IV,Factor IV,Blood Coagulation Factor IV,Calcium-40,Calcium 40,Factor IV, Coagulation
D002147	Calmodulin	A heat-stable, low-molecular-weight activator protein found mainly in the brain and heart. The binding of calcium ions to this protein allows this protein to bind to cyclic nucleotide phosphodiesterases and to adenyl cyclase with subsequent activation. Thereby this protein modulates cyclic AMP and cyclic GMP levels.	Calcium-Dependent Activator Protein,Calcium-Dependent Regulator,Bovine Activator Protein,Cyclic AMP-Phosphodiesterase Activator,Phosphodiesterase Activating Factor,Phosphodiesterase Activator Protein,Phosphodiesterase Protein Activator,Regulator, Calcium-Dependent,AMP-Phosphodiesterase Activator, Cyclic,Activating Factor, Phosphodiesterase,Activator Protein, Bovine,Activator Protein, Calcium-Dependent,Activator Protein, Phosphodiesterase,Activator, Cyclic AMP-Phosphodiesterase,Activator, Phosphodiesterase Protein,Calcium Dependent Activator Protein,Calcium Dependent Regulator,Cyclic AMP Phosphodiesterase Activator,Factor, Phosphodiesterase Activating,Protein Activator, Phosphodiesterase,Protein, Bovine Activator,Protein, Calcium-Dependent Activator,Protein, Phosphodiesterase Activator,Regulator, Calcium Dependent
D002352	Carrier Proteins	Proteins that bind or transport specific substances in the blood, within the cell, or across cell membranes.	Binding Proteins,Carrier Protein,Transport Protein,Transport Proteins,Binding Protein,Protein, Carrier,Proteins, Carrier
D002712	Chlorides	Inorganic compounds derived from hydrochloric acid that contain the Cl- ion.	Chloride,Chloride Ion Level,Ion Level, Chloride,Level, Chloride Ion
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D001692	Biological Transport	The movement of materials (including biochemical substances and drugs) through a biological system at the cellular level. The transport can be across cell membranes and epithelial layers. It also can occur within intracellular compartments and extracellular compartments.	Transport, Biological,Biologic Transport,Transport, Biologic