Biomaterial Database

Studies on the mechanism of the positive inotropic effect of ATX II (Anemonia sulcata) on isolated guinea pig atria. 1982

C Alsen, and T Peters, and E Scheufler

The basic polypeptide ATX II (MW 4,770) isolated from the sea anemone Anemonia sulcata evokes a pronounced and dose-dependent positive inotropic effect in different mammalian heart preparations. The mechanism of this effect is so far unknown. (a) Investigations on isolated guinea pig atria indicate that changes of the steady state cellular Na, K and Ca concentrations cannot account for the positive inotropic effect. (b) An increase of the surface pressure of phospholipid monolayers was observed only at cardiotoxic ATX II concentrations. However, the 45Ca binding to phosphatidylserine, as the essential Ca-binding phospholipid, was not changed even at cardiotoxic ATX II concentrations. (c) Neither the enzymatic activity nor the ouabain inhibition kinetic of an isolated Na/K-ATPase preparation was affected by ATX II. (d) In intact electrically stimulated (1 Hz) guinea pig atria the binding of [3H]ouabain increases by about 50% at a positive inotropic ATX II concentration. The results suggest that the positive inotropic effect of ATX II is not caused by an unspecific membrane damaging action or by a direct interaction with the Na/K-ATPase. The increased binding of [3H]ouabain to intact heart muscles indirectly reflects an increased pump activity of the Na/K-ATPase, which is caused by an elevated Na transient due to the electrophysiologically well-established mechanism of the ATX II action on fast Na channel, i.e., delayed inactivation of the fast Na flux. However, the exact mechanism of the ATX II induced positive inotropic effect remains unknown.

UI	MeSH Term	Description	Entries
D009200	Myocardial Contraction	Contractile activity of the MYOCARDIUM.	Heart Contractility,Inotropism, Cardiac,Cardiac Inotropism,Cardiac Inotropisms,Contractilities, Heart,Contractility, Heart,Contraction, Myocardial,Contractions, Myocardial,Heart Contractilities,Inotropisms, Cardiac,Myocardial Contractions
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
D009498	Neurotoxins	Toxic substances from microorganisms, plants or animals that interfere with the functions of the nervous system. Most venoms contain neurotoxic substances. Myotoxins are included in this concept.	Alpha-Neurotoxin,Excitatory Neurotoxin,Excitotoxins,Myotoxin,Myotoxins,Neurotoxin,Alpha-Neurotoxins,Excitatory Neurotoxins,Excitotoxin,Alpha Neurotoxin,Alpha Neurotoxins,Neurotoxin, Excitatory,Neurotoxins, Excitatory
D010042	Ouabain	A cardioactive glycoside consisting of rhamnose and ouabagenin, obtained from the seeds of Strophanthus gratus and other plants of the Apocynaceae; used like DIGITALIS. It is commonly used in cell biological studies as an inhibitor of the NA(+)-K(+)-EXCHANGING ATPASE.	Acocantherin,G-Strophanthin,Acolongifloroside K,G Strophanthin
D010743	Phospholipids	Lipids containing one or more phosphate groups, particularly those derived from either glycerol (phosphoglycerides see GLYCEROPHOSPHOLIPIDS) or sphingosine (SPHINGOLIPIDS). They are polar lipids that are of great importance for the structure and function of cell membranes and are the most abundant of membrane lipids, although not stored in large amounts in the system.	Phosphatides,Phospholipid
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
D003063	Cnidaria	A phylum of radially symmetrical invertebrates characterized by possession of stinging cells called nematocysts. It includes the classes ANTHOZOA; CUBOZOA; HYDROZOA, and SCYPHOZOA. Members carry CNIDARIAN VENOMS.	Cnidarians,Cnidarian,Cnidarias
D003064	Cnidarian Venoms	Venoms from jellyfish; CORALS; SEA ANEMONES; etc. They contain hemo-, cardio-, dermo- , and neuro-toxic substances and probably ENZYMES. They include palytoxin, sarcophine, and anthopleurine.	Chironex Venoms,Jellyfish Venoms,Nematocyst Venoms,Sea Anemone Venoms,Chironex Venom,Cnidarian Venom,Jellyfish Venom,Portuguese Man-of-War Venom,Sea Anemone Venom,Portuguese Man of War Venom,Venom, Chironex,Venom, Cnidarian,Venom, Jellyfish,Venom, Portuguese Man-of-War,Venom, Sea Anemone,Venoms, Chironex,Venoms, Cnidarian,Venoms, Jellyfish,Venoms, Nematocyst,Venoms, Sea Anemone
D004573	Electrolytes	Substances that dissociate into two or more ions, to some extent, in water. Solutions of electrolytes thus conduct an electric current and can be decomposed by it (ELECTROLYSIS). (Grant & Hackh's Chemical Dictionary, 5th ed)	Electrolyte
D006168	Guinea Pigs	A common name used for the genus Cavia. The most common species is Cavia porcellus which is the domesticated guinea pig used for pets and biomedical research.	Cavia,Cavia porcellus,Guinea Pig,Pig, Guinea,Pigs, Guinea