Sinus

Both coils are constructed in the same way, geometry and number of windings are equal. A permanent sinus current flows through these coils and excites an electromagnetic field around each coils. 

Other Infections. The slowly excreted sulfonamides (eg, sulfamethoxypyrida2ine, sulfadimethoxine) are used for treatment of minor infections such as sinusitis or otitis, or for prolonged maintenance therapy. Soluble sulfonamides are sometimes used for proto2oal infections in combination with other agents. Pyrimethamine, combined with sulfonamides, has been used for toxoplasmosis or leishmaniasis, and trimethoprim with sulfonamides has been used in some types of malaria. In nocardiosis, sulfonamides have been used with cycloserine [68-41-7] (17). 

Rhinitis is characterized by nasal stuffiness with partial or full obstmction, and itching of the nose, eyes, palate, or pharynx, sneezing, and rhinorrhoea. If left untreated it can lead to more serious respiratory diseases such as sinusitis or asthma. Although several types of dmgs are available for treatment, nasal spray topical corticosteroids are widely regarded as the reference standard in rhinitis therapy (250). 

Arrhythmias Originating in the Sinus Node Sinus bradycardia Sick sinus syndrome Sinus tachycardia Disorders of Impulseformation ... 

Indeca.inide. Indecainide hydrochloride is a po active antiarrhythmic agent that received PDA approval in 1989, but it has not been marketed as of this writing. Chemically, it is 9-[3-(isopropylamino)propyl]fiuorine-9-carboxamide [74517-78-5]. The dmg has potent activity against premature ventricular complexes (PVCs) and ventricular tachycardias. Indecainide has no effect on sinus node function, atrial or ventricular effective refractory periods (32,33). 

Pirmenol. Pirmenol hydrochloride, a pyridine methanol derivative, is a racemic mixture. It has Class lA antiarrhythmic activity, ie, depression of fast inward sodium current, phase 0 slowing, and action potential prolongation. The prolongation of refractory period may be a Class III property. This compound has shown efficacy in converting atrial arrhythmias to normal sinus rhythm (34,35). 

Propranolol. Propranolol hydrochloride, considered the prototype of the P-adrenoceptor blocking agents, has been in use since 1964. It is a nonselective, highly Hpid-soluble P-adrenoceptor blocker having no ISA. It is a mixture of (+) and (—) enantiomers, and the (—) enantiomer is the active moiety. The local anesthetic effects of propranolol are equipotent to those of Hdocaine [137-58-6] C 4H22N20, (see Anesthetics). Therapeutic effects include termination of catecholamine-induced arrhythmias, conversion of SA nodal tachycardias (including flutter and fibrillation) and AV nodal tachyarrhythmias to normal sinus rhythm, digitahs-induced arrhythmias, and ventricular arrhythmias (1,2). The dmg also has cardioprotective properties (37,39). 

The electrophysiological effects of amiodarone may be a composite of several properties. In addition to prolonging action potential duration and refractory period in ad tissues of the heart, the compound is an effective sodium channel blocker (49), calcium channel blocker (50), and a weak noncompetitive -adrenoceptor blocking agent (51). Amiodarone slows the sinus rate, markedly prolongs the QT interval, and slightly prolongs the QRS duration (1,2). 

Greanwood. A.. Blrciriral Tnrnsiems in Bow er S < sinus. John Wiley. New York. 

Reimer, A., von Mecklenberg, C., and Toremalm, N. G. (1978). The mucociliary activity of the upper respiratory tract. III. A functional and morphological study on human and animal mare-tial with special reference to maxillary sinus diseases. Acta Otolaryngol., 1-20. 

Arcus-cosinus, m. (Math.) inverse cosine, arc cos, cos i. -sinus, m. (Math.) inverse sine, arc sin, sin i. 

Sinus, m. (Math.) sine (Anai.) sinus, sinus-ahnlich, a. sinus-like, sinusoidal, -fdnnig, a. sinus-shaped, sinusoidal. 

Sinus-kurve, -linie, /. sine curve, sinuskurvenartlg, a. sinusoidal, siphonieren, v.t. siphon. 

Normal rhythmic activity is the result of the activity of the sinus node generating action potentials that are conducted via the atria to the atrioventricular node, which delays further conduction to the His-Tawara-Purkinje system. From the Purkinje fibres, action potentials propagate to the ventricular myocardium. Arrhythmia means a disturbance of the normal rhythm either resulting in a faster rhythm (tachycardia, still rhythmic) or faster arrhythmia (tachyarrhythmia) or slowed rhythm (bradycardia, bradyarrhythmia). 

In the following, the cardiac action potential is explained (Fig. 1) An action potential is initiated by depolarization of the plasma membrane due to the pacemaker current (If) (carried by K+ and Na+, which can be modulated by acetylcholine and by adenosine) modulated by effects of sympathetic innervation and (3-adrenergic activation of Ca2+-influx as well as by acetylcholine- or adenosine-dependent K+-channels [in sinus nodal and atrioventricular nodal cells] or to dqjolarization of the neighbouring cell. Depolarization opens the fast Na+ channel resulting in a fast depolarization (phase 0 ofthe action potential). These channels then inactivate and can only be activated if the membrane is hyperpolarized... 

Not all cells in the heart express the fast sodium channel. Thus, sinus nodal and atrioventricular nodal cells lack the fast Na+ channel and instead generate their action potentials via opening of Ca2+ channels. This is the basis for their sensitivity to Ca2+ antagonists. 

Class II drugs are classical (3-adrenoceptor antagonists such as propranolol, atenolol, metoprolol or the short-acting substance esmolol. These drugs reduce sinus rate, exert negative inotropic effects and slow atrioventricular conduction. Automaticity, membrane responsiveness and effective refractory period of Purkinje fibres are also reduced. The typical extracardiac side effects are due to (3-adrenoceptor blockade in other organs and include bronchospasm, hypoglycemia, increase in peripheral vascular resistance, depressions, nausea and impotence. 

Class II antiarrhythmic drugs are (3-adrenoceptor antagonists such as propranolol, metoprolol or atenolol. (3-adrenoceptor antagonists slow sinus rate and atrioventricular conduction and exert negative inotropic effects. 

Class IV antiarrhythmic drugs are Ca2+ channel blockers, which predominantly slow sinus rate and atrioventricular conduction and thus are used in the treatment of supraventricular tachyarrhythmias. These drugs exert a pronounced negative inotropic effect. 

The regulation of the total peripheral resistance also involves the complex interactions of several mechanisms. These include baroreflexes and sympathetic nervous system activity response to neurohumoral substances and endothelial factors myogenic adjustments at the cellular level, some mediated by ion channels and events at the cellular membrane and intercellular events mediated by receptors and mechanisms for signal transduction. As examples of some of these mechanisms, there are two major neural reflex arcs (Fig. 1). Baroreflexes are derived from high-pressure barorecep-tors in the aortic arch and carotid sinus and low-pressure cardiopulmonary baroreceptors in ventricles and atria. These receptors respond to stretch (high pressure) or... 

Inhibition of the Na+/K+-ATPase leads to a loss of potassium and an increase of sodium within the cell. Secondary intracellular calcium is increased via the Na VCa -exchanger. This results in a positive inotropic effect in the myocardium, with an increase of peak force and a decrease in time to peak tension. Besides this, cardiac glycosides increase vagal activity by effects on the central vagal nuclei, the nodose ganglion and increase in sensitivity of the sinus node to acetylcholine. 

Cardiac glycosides have a small ratio of toxic to therapeutic concentration. Possible adverse effects are nausea, vomiting, abdominal pain, diarrhoea, fatigue, headache, drowsiness, colour vision disturbances, sinus bradycardia, premature ventricular complexes, AV-block, bigeminy, atrial tachycardia with AV-Block, ventricular fibrillation. There are several mechanisms relevant for their toxic action (Table 2). 

The sinus rhythm is the heart rhythm in which the sinus node generates an electrical impulse that travels through specialized cells (that form a conduction system) and leads to a ventricular contraction. 

The LVA channels are expressed in a wide variety of tissues. In the cardiac sinus node and the thalamus, activation of LVA channels seems to be necessary to generate action potentials upon depolarising the membrane. 

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