Ventricles of the heart

The direct injection of potent vasodilatory agents such as papaverine or isosor-bide dinitrate, into the ventricles of the heart reverses the action of palytoxin in approximately one-half of the animals. These extreme measures are required because palytoxin kills quickly. Antidotes injected into the venous circulation were not able to reach the heart because the stagnation of venous blood occurs so rapidly that antidotes are simply pooled on the venous side of the circulation and never reach the heart. In these studies isosorbide dinitrate appeared to be approximately twice as effective as papaverine in reversing the toxic effects of palytoxin. 

Continual pumping of blood by muscles of the atria and ventricles of the heart. 

Amiodarone s antiarrhythmic action is connected to its ability to block K, Na, and Ca channels while noncompetitively blocking a- and j3-adrenergic receptors of the heart, thus prolonging the action potential and effective refractive period of atrial cells, atrioventricular junctions, and ventricles of the heart, which is accompanied by decreased automatism of sinus node and slowing of atrioventricular conductivity. 

Pharmacology Procainamide, a class lA antiarrhythmic, increases the effective refractory period of the atria, and to a lesser extent the bundle of His-Purkinje system and ventricles of the heart. 

Pulse The rhythmical expansion and contraction of an artery produced by waves of pressure caused by the ejection of blood from the left ventricle of the heart as it contracts. 

Historically and romantically, the heartbeat is recognized as the quintessential hallmark of life. Normally, the heart beats at 60-100 beats per minute (bpm), with each beat yielding a ventricular contraction that ejects blood out to the body. Each heartbeat is an electrical event that originates from a collection of electrically excitable cells within the heart called the sinoatrial node (SA), anatomically located at the upper pole of the heart. The sinoatrial node is the primary pacemaker of the heart. The electrical impulse generated in the sinoatrial node spreads rapidly downward from the atria chambers of the heart and reaches the atrioventricular node (AV), a collection of electrically excitable cells that constitutes the electrical interface between the atria and ventricles of the heart. Erom the AV node, the impulse propagates throughout the ventricles via an electrical conduction system referred to as the His-Purkinje system. The electrical transmission... 

His tendency was the same as that of nearly all medical chemists of his period—to accept a plausible analogy instead of waiting for more basis in facts for his conclusions. Especially notable was his attempt to make the chemical function of the body depend on action between acids and alkalies. So for instance he said that in the right auricle and ventricle of the heart, the blood in its circulation meets the blood charged with bile. The mixture of these two effervesces on contact like iron and oil of vitriol. This is the source of animal heat. The function of respiration he concludes is to temper the heat produced by this effervescence, and expiration from the lungs carries away the vapors produced by the effervescense. 

Olcott CT. 1950. Experimental argyrosis. V. Hypertrophy of the left ventricle of the heart. Archives of Pathology 49 138-149. 

Preparation of Microsomal and Cytosolic Fractions. At the end of the 5 week period on experimental diets, all animals were killed via sodium pentobarbital anesthesia (120mg/kg body weight). The tissues were perfused in situ with ice-cold normal saline via the right ventricle of the heart, excised, trimmed free of connective tissue, minced, and washed thoroughly with ice-cold deionized water. The subcellular fractions of liver, lungs, kidneys, etc., were prepared as previously described (26). 

A fairly new observation shows the ability of omega-3 fatty acids to lower blood pressure. They appear to do so by reducing resistance to surges of blood flow in the arteries. That, in turn, improves performance of the left ventricle of the heart, the muscular pump. What we have, as a result, is healthier arteries that are less stiff and more flexible, as well as a more powerful heart muscle, both of which improve blood flow and hence reduce blood pressure. 

Peripheral venous blood reaches the pulmonary circulation from the right ventricle of the heart and is arterialized in the capillaries of the lungs by uptake of O2 and loss of CO2. Pulmonary venous blood then returns to the left ventricle by way of the left atrium and is pumped through the aorta to the peripheral tissues. In the capillaries of peripheral tissues, the arterial blood releases O2 to the tissue cells and takes up CO2. With return of blood to the lungs, the cycle is completed. 

Perform a thoracotomy to expose the thoracic organs and to gain access to the heart. Cut a small hole in the right ventricle of the heart. 

Insert a 25-gauge butterfly infusion needle into the left ventricle of the heart and perfuse the animal with 60 mL of PBS (seeNotes 17 and 18). 

It has been shown in some instances that extremely small fractions of the cellular surfaces need to be affected to elicit a drug response. It can be calculated that the dose of acetylcholine needed to reduce the heartbeat of a toad by 50% would cover only 0.016% of the surface area of the cells in the ventricle of the heart. 

Elastin is the major protein found in elastic fibers, which are located in the ECM of connective tissue of smooth muscle cells, endothelial and microvascular cells, chondrocytes, and fibroblasts. Elastic fibers allow tissues to expand and contract this is of particular importance to blood vessels, which must deform and reform repeatedly in response to the changes in intravascular pressure that occur with the contraction of the left ventricle of the heart. It is also important for the lungs, which stretch each time a breath is inhaled and return to their original shape with each exhalation. In addition to elastin, the elastic fibers contain microfibrils, which are composed of a number of acidic glycoproteins, the major ones being fibrillin-1 and fibrillin-2. 

A cardiac muscle cell beneath the endocardium of the ventricles of the heart. These extend from the bundle branches to the ventricular myocardium and form the last part of the cardiac conduction system. 

---