Myocardial Contraction
Contractile activity of the MYOCARDIUM.
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.
Ventricular Function
The hemodynamic and electrophysiological action of the HEART VENTRICLES.
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.
Systole
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.
Ventricular Function, Left
Ventricular Dysfunction, Left
A condition in which the LEFT VENTRICLE of the heart was functionally impaired. This condition usually leads to HEART FAILURE; MYOCARDIAL INFARCTION; and other cardiovascular complications. Diagnosis is made by measuring the diminished ejection fraction and a depressed level of motility of the left ventricular wall.
Echocardiography
Ultrasonic recording of the size, motion, and composition of the heart and surrounding tissues. The standard approach is transthoracic.
Coronary Circulation
The circulation of blood through the CORONARY VESSELS of the HEART.
Calcium
A basic element found in nearly all organized 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.
Dogs
Myocytes, Cardiac
Striated muscle cells found in the heart. They are derived from cardiac myoblasts (MYOBLASTS, CARDIAC).
Isometric Contraction
Muscle, Smooth
Unstriated and unstriped muscle, one of the muscles of the internal organs, blood vessels, hair follicles, etc. Contractile elements are elongated, usually spindle-shaped cells with centrally located nuclei. Smooth muscle fibers are bound together into sheets or bundles by reticular fibers and frequently elastic nets are also abundant. (From Stedman, 25th ed)
Muscle, Skeletal
Isotonic Contraction
Vasoconstriction
Guinea Pigs
Muscle Fatigue
A state arrived at through prolonged and strong contraction of a muscle. Studies in athletes during prolonged submaximal exercise have shown that muscle fatigue increases in almost direct proportion to the rate of muscle glycogen depletion. Muscle fatigue in short-term maximal exercise is associated with oxygen lack and an increased level of blood and muscle lactic acid, and an accompanying increase in hydrogen-ion concentration in the exercised muscle.
Electromyography
Potassium Chloride
Trachea
Peristalsis
A movement, caused by sequential muscle contraction, that pushes the contents of the intestines or other tubular organs in one direction.
Urinary Bladder
Norepinephrine
Precursor of epinephrine that is secreted by the adrenal medulla and is a widespread central and autonomic neurotransmitter. Norepinephrine is the principal transmitter of most postganglionic sympathetic fibers and of the diffuse projection system in the brain arising from the locus ceruleus. It is also found in plants and is used pharmacologically as a sympathomimetic.
Dose-Response Relationship, Drug
Acetylcholine
Rabbits
Atropine
An alkaloid, originally from Atropa belladonna, but found in other plants, mainly SOLANACEAE. Hyoscyamine is the 3(S)-endo isomer of atropine.
Phenylephrine
Vas Deferens
Ileum
Nifedipine
A potent vasodilator agent with calcium antagonistic action. It is a useful anti-anginal agent that also lowers blood pressure.