Biomaterial Database

Modulation of Na+-Ca2+ exchange and Ca2+ permeability in cardiac sarcolemmal vesicles by doxylstearic acids. 1987

K D Philipson, and R Ward

We examine the effects of 5-, 12- and 16-doxylstearic acids on the Na+-Ca2+ exchange and passive Ca2+ permeability of cardiac sarcolemmal vesicles. Stearic acid is a weak stimulator of Na+-Ca2+ exchange. A doxyl moiety potentiates stimulation with the order of increasing potency being 5-, 12- and then 16-doxylstearic acid. Stearic acid has little effect on vesicle Ca2+ permeability but again the doxylstearates are more effective. The sequence of potency is reversed, however, from that for increasing Na+-Ca2+ exchange. 5-Doxylstearic acid most markedly exchanges passive Ca2+ flux followed by the 12-, and then 16-doxylstearic acids. Methyl esters of the doxylstearates have no effect on either Na+-Ca2+ exchange or Ca2+ permeability. We model the results as follows. For a fatty acid to stimulate Na+-Ca2+ exchange activity, an anionic charge is required to interact with the exchanger protein at the membrane surface. Stimulation is potentiated by a perturbation (such as provided by a doxyl group) within the lipid bilayer. The perturbation is most effective at a location towards the center of the bilayer. To increase passive Ca2+ permeability an anionic charge is again essential. Disorder within the bilayer is also important, but now the most important site is near the membrane surface. Results of experiments with linolenic and gamma-linolenic acid and previous studies with other fatty acids also support this model.

UI	MeSH Term	Description	Entries
D008042	Linolenic Acids	Eighteen-carbon essential fatty acids that contain three double bonds.
D008051	Lipid Bilayers	Layers of lipid molecules which are two molecules thick. Bilayer systems are frequently studied as models of biological membranes.	Bilayers, Lipid,Bilayer, Lipid,Lipid Bilayer
D009206	Myocardium	The muscle tissue of the HEART. It is composed of striated, involuntary muscle cells (MYOCYTES, CARDIAC) connected to form the contractile pump to generate blood flow.	Muscle, Cardiac,Muscle, Heart,Cardiac Muscle,Myocardia,Cardiac Muscles,Heart Muscle,Heart Muscles,Muscles, Cardiac,Muscles, Heart
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
D002463	Cell Membrane Permeability	A quality of cell membranes which permits the passage of solvents and solutes into and out of cells.	Permeability, Cell Membrane
D003497	Cyclic N-Oxides	Heterocyclic compounds in which an oxygen is attached to a cyclic nitrogen.	Heterocyclic N-Oxides,Cyclic N Oxides,Heterocyclic N Oxides,N Oxides, Cyclic,N-Oxides, Cyclic,N-Oxides, Heterocyclic,Oxides, Cyclic N
D004058	Diffusion	The tendency of a gas or solute to pass from a point of higher pressure or concentration to a point of lower pressure or concentration and to distribute itself throughout the available space. Diffusion, especially FACILITATED DIFFUSION, is a major mechanism of BIOLOGICAL TRANSPORT.	Diffusions
D004285	Dogs	The domestic dog, Canis familiaris, comprising about 400 breeds, of the carnivore family CANIDAE. They are worldwide in distribution and live in association with people. (Walker's Mammals of the World, 5th ed, p1065)	Canis familiaris,Dog
D006352	Heart Ventricles	The lower right and left chambers of the heart. The right ventricle pumps venous BLOOD into the LUNGS and the left ventricle pumps oxygenated blood into the systemic arterial circulation.	Cardiac Ventricle,Cardiac Ventricles,Heart Ventricle,Left Ventricle,Right Ventricle,Left Ventricles,Right Ventricles,Ventricle, Cardiac,Ventricle, Heart,Ventricle, Left,Ventricle, Right,Ventricles, Cardiac,Ventricles, Heart,Ventricles, Left,Ventricles, Right
D000001	Calcimycin	An ionophorous, polyether antibiotic from Streptomyces chartreusensis. It binds and transports CALCIUM and other divalent cations across membranes and uncouples oxidative phosphorylation while inhibiting ATPase of rat liver mitochondria. The substance is used mostly as a biochemical tool to study the role of divalent cations in various biological systems.	4-Benzoxazolecarboxylic acid, 5-(methylamino)-2-((3,9,11-trimethyl-8-(1-methyl-2-oxo-2-(1H-pyrrol-2-yl)ethyl)-1,7-dioxaspiro(5.5)undec-2-yl)methyl)-, (6S-(6alpha(2S,3S),8beta(R*),9beta,11alpha))-,A-23187,A23187,Antibiotic A23187,A 23187,A23187, Antibiotic