Biomaterial Database

Emodin-induced muscle contraction of mouse diaphragm and the involvement of Ca2+ influx and Ca2+ release from sarcoplasmic reticulum. 1998

Y W Cheng, and J J Kang

Institute of Toxicology, College of Medicine, National Taiwan University, Taipei, ROC.

1. The effects on skeletal muscle of emodin, an anthraquinone, were studied in the mouse isolated diaphragm and sarcoplasmic reticulum (SR) membrane vesicles. 2. Emodin dose-dependently caused muscle contracture, simultaneously depressing twitch amplitude. Neither tubocurarine nor tetrodotoxin blocked the contraction suggesting that it was caused myogenically. 3. The contraction induced by emodin persisted in a Ca2+ free medium with a slight reduction in the maximal force of contraction. The contraction induced by emodin in the Ca2+ free medium was completely blocked when the internal Ca2+ pool of the muscle was depleted by ryanodine. These data suggest that the contraction caused by emodin is due to the release of Ca2+ from the intracellular ryanodine-sensitive pool. 4. In contrast to the effect seen in the Ca2+ free medium, emodin induced a small but consisted contraction in the ryanodine-treated muscle in Krebs medium. The contraction was blocked in the presence of dithiothreitol and was partially blocked by nifedipine, suggesting that oxidation of a sulphhydryl group on the external site of dihydropyridine receptor is involved. 5. Emodin dose-dependently increased Ca2+ release from actively loaded SR vesicles and this effect was blocked by ruthenium red, a specific Ca2+ release channel blocker, and the thiol reducing agent, DTT, suggesting that emodin induced Ca2+ release through oxidation of the critical SH of the ryanodine receptor. 6. [3H]-ryanodine binding was dose-dependently potentiated by emodin in a biphasic manner. The degree of potentiation of ryanodine binding by emodin increased dose-dependently at concentrations up to 10 microM but decreased at higher concentrations of 10-100 microM. 7. These data suggest that muscle contraction induced by emodin is due to Ca2+ release from the SR of skeletal muscle, as a result of oxidation of the ryanodine receptor and influx of extracellular Ca2+ through voltage-dependent Ca2+ channels of the plasma membrane.

UI	MeSH Term	Description	Entries
D008297	Male		Males
D008813	Mice, Inbred ICR	An inbred strain of mouse that is used as a general purpose research strain, for therapeutic drug testing, and for the genetic analysis of CARCINOGEN-induced COLON CANCER.	Mice, Inbred ICRC,Mice, ICR,Mouse, ICR,Mouse, Inbred ICR,Mouse, Inbred ICRC,ICR Mice,ICR Mice, Inbred,ICR Mouse,ICR Mouse, Inbred,ICRC Mice, Inbred,ICRC Mouse, Inbred,Inbred ICR Mice,Inbred ICR Mouse,Inbred ICRC Mice,Inbred ICRC Mouse
D009119	Muscle Contraction	A process leading to shortening and/or development of tension in muscle tissue. Muscle contraction occurs by a sliding filament mechanism whereby actin filaments slide inward among the myosin filaments.	Inotropism,Muscular Contraction,Contraction, Muscle,Contraction, Muscular,Contractions, Muscle,Contractions, Muscular,Inotropisms,Muscle Contractions,Muscular Contractions
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
D003964	Diaphragm	The musculofibrous partition that separates the THORACIC CAVITY from the ABDOMINAL CAVITY. Contraction of the diaphragm increases the volume of the thoracic cavity aiding INHALATION.	Respiratory Diaphragm,Diaphragm, Respiratory,Diaphragms,Diaphragms, Respiratory,Respiratory Diaphragms
D004642	Emodin	Purgative anthraquinone found in several plants, especially RHAMNUS PURSHIANA. It was formerly used as a laxative, but is now used mainly as a tool in toxicity studies.	Casanthranol,Frangula Emodin,Peristim,Rheum Emodin,Archin,Frangulic Acid,Emodin, Frangula,Emodin, Rheum
D005260	Female		Females
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D012433	Ryanodine	A methylpyrrole-carboxylate from RYANIA that disrupts the RYANODINE RECEPTOR CALCIUM RELEASE CHANNEL to modify CALCIUM release from SARCOPLASMIC RETICULUM resulting in alteration of MUSCLE CONTRACTION. It was previously used in INSECTICIDES. It is used experimentally in conjunction with THAPSIGARGIN and other inhibitors of CALCIUM ATPASE uptake of calcium into SARCOPLASMIC RETICULUM.
D012519	Sarcoplasmic Reticulum	A network of tubules and sacs in the cytoplasm of SKELETAL MUSCLE FIBERS that assist with muscle contraction and relaxation by releasing and storing calcium ions.	Reticulum, Sarcoplasmic,Reticulums, Sarcoplasmic,Sarcoplasmic Reticulums