Cardiovascular system circulation

Jaffer, E.A. and Weissleder, R. (2004) Seeing within molecular imaging of the cardiovascular system. Circulation Research, 94,433-45. 

Atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), and C-type natriuretic peptide (CNP) are members of a family of so-called natriuretic peptides, synthesized predominantly in the cardiac atrium, ventricle, and vascular endothelial cells, respectively (G13, Y2). ANP is a 28-amino-acid polypeptide hormone released into the circulation in response to atrial stretch (L3). ANP acts (Fig. 8) on the kidney to increase sodium excretion and glomerular filtration rate (GFR), to antagonize renal vasoconstriction, and to inhibit renin secretion (Ml). In the cardiovascular system, ANP antagonizes vasoconstriction and shifts fluid from the intravascular to the interstitial compartment (G14). In the adrenal cortex, ANP is a powerful inhibitor of aldosterone synthesis (E6, N3). At the hypothalamic level, ANP inhibits vasopressin secretion (S3). It has been shown that some of the effects of ANP are mediated via a newly discovered hormone, called adreno-medullin, controlling fluid and electrolyte homeostasis (S8). The diuretic and blood pressure-lowering effect of ANP may be partially due to adrenomedullin (V5). 

The most important actions of the (3-blocking drugs are on the cardiovascular system. -Blockers decrease heart rate, myocardial contractility, cardiac output, and conduction velocity within the heart. These effects are most pronounced when sympathetic activity is high or when the heart is stimulated by circulating agonists. 

Any implications for the reproductive system arising from an effect on the homeostasis of the major body systems should be considered. For example, compounds that affect the contractility of smooth muscle might be expected to affect the reproductive tract compounds affecting the cardiovascular system might be expected to have an effect in gestation via the maternal circulation or directly on the embryonic cardiovascular system as it develops. 

A complication of diabetes where painful nerve damage can affect the limbs (especially causing ulcers in the feet if the patient has poor blood circulation), intestinal and cardiovascular system. 

Several epidemiological studies show that fine and ultrafine (<0.1 pm) particulate matter and air pollution can pose adverse health effects including respiratory, cardiovascular, allergic, and carcinogenic diseases (Kiinzli et al., 2000 Donaldson et al., 2003 Bernstein et al., 2004). It appears also that ultrafine particles, after deposition in the lung and gain access to the pulmonary interstitium, can penetrate the systemic circulation and exert more toxicity than coarse and fine particles (Oberdorster, 2001 Bernstein et al., 2004). 

The system that circulates blood is the cardiovascular system, shown in schematic form in Figure 9.1. It consists of two major components the muscular part of the heart, called the myocardium, and the network of blood vessels composed of arteries, veins, and capillaries. Blood circulation is the body s transportation system that supplies tissues with the oxygen, nutrients and their metabolites, and hormones that they need for their function. Blood carries carbon dioxide, encapsulated dead cell matter, and other wastes away from tissues. Circulating blood is crucial to maintaining body homeostasis, with temperature, pH, and other crucial parameters kept within the narrow ranges required for good health. A number of toxicants have adverse effects on the cardiovascular system. 

K. Lagana et al Multiscale modeling of the cardiovascular system application to the study of pulmonary and coronary perfusions in the univentricular circulation. J. Biomech. 38, 1129-141 (2004)... 

Cocaine may directly affect the fetal cardiovascular system or do so by increasing the concentrations of circulating catecholamines and activating the sympathetic nervous system. 

Atracurium is unique in that it is altered spontaneously in the body to an inactive form (t 30 min) by a passive chemical process (Hofmann elimination). The duration of action (15-35 min) is thus uninfluenced by the state of the circulation, the liver or the kidneys, a significant advantage in patients with hepatic or renal disease and in the aged. It has very little direct effect on the cardiovascular system... 

Apart from rare reports of variant angina pectoris and vasculitis theoretically related to thromboxane, aspirin is not associated with adverse effects on the cardiovascular system (17,18), except an increase in circulating plasma volume after large doses. 

The respiratory and cardiovascular adverse effects of topical therapy with timolol or betaxolol have been studied in a randomized, controlled trial in 40 elderly patients with glaucoma (83). Five of the 20 allocated to timolol discontinued treatment for respiratory reasons, compared with three of the 20 patients allocated to betaxolol There were no significant differences in mean values of spirometry, pulse, or blood pressure between the groups. This study confirms that beta-blockers administered as eye-drops can reach the systemic circulation and that serious adverse respiratory events can occur in elderly people, even if they are screened before treatment for cardiac and respiratory disease. These events can occur using either the selective betaxolol agent or the non-selective timolol. 

Caffeine can have profound effects on the cardiovascular system. At least four mechanisms have been proposed for the pro-arrhythmic potential of caffeine in overdose. First, caffeine increases circulating catecholamines. Second, caffeine inhibits phosphodiesterase. Increased circulating catecholamines after caffeine overdose increase jSl-receptor stimulation. Stimulation of jSl-receptors increases intracellular cAMP by G protein stimulation of adenylate cyclase. The activity of cAMP is prolonged due to its decreased metabolism as phosphodiesterase is inhibited by caffeine. Subsequently, jSl-receptor effects are exaggerated and tachydysrhythmias are induced. Third, caffeine increases myocardial intracellular calcium. Caffeine both induces release of calcium... 

Phosphorus can be absorbed into the systemic circulation from the skin, lungs, and intestinal tract. For all practical purposes, white and yellow phosphorus are readily absorbed while red phosphorus is not. The target organs of toxicity include the gastrointestinal tract, liver, kidney, bone, and the cardiovascular and central nervous systems. 

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