| Atrial fibrillation(AF) is characterized by rapid and irregular activation of the atrium, for example, 400-600 pulses of the atrium muscular wall per minute in humans. The occurrence of AF increases with age, with a prevalence rising from 0.5% of people in their 50s to nearly 10% of the octogenarian population. Several cardiac disorders predispose to AF, including pericarditis, mitral valve disease, congenital heart disease, congestive heart failure(CHF), thyrotoxic heart disease and hypertension. Many of these are thought to promote AF by increasing atrial pressure and/or by causing atrial dilation; however, the precise mechanistic links are incompletely defined. AF also occurs in individuals without any other evidence of heart or systemic disease―a condition known as 'lone AF'. AF is a very common rhythm disturbance for which treatment remains problematic. Our understanding of AF pathophysiology has evolved greatly over the last 10 years but remains incomplete. An improved understanding of AF pathophysiology may lead to improved therapeutic approaches. Preventing the onset of AF rather than its complications is important from the point of view of public health. Yet neither its incidence nor its risk factors are well characterized in population-based studies. Several studies report on risk factors for chronic AF, but only the Framingham study has also included transitory AF as an outcome of interest. In a recent report reflecting 38 years of follow-up, the risk factors for transitory or chronic AF were male sex, age, diabetes, hypertension, congestive heart failure, valvular heart disease, and a history of myocardial infarction. Identifying risk factors might enhance efforts directed at the primary prevention of AF. People regard effect of ischemia on atrial myocardium as important, because it related to the ralationship of CAD and AF, but untill now, the conclusion is unknown. The Framingham study had reported a weak relationship between ischemic heart disease and atrial fibrillatiom, but Andrew found ischemic heart disease was a powerful risk factor of atrial fibrillation, the risk was highest for myocardial infarction, but also significant for stable and unstable angina. Krahn found congestive heart failure, an obvious potential mediator between CAD and AF, appeared to be present in only a minority of patients with AF and CAD. In addition, although the incidence is declining, AF remains a common complication of acute myocardial infarction. The possibility that atrial ischemia may contribute to the occurrence of AF has received relatively little attention, and we were unable to identify any published experimental studies examining the effects of isolated atrial ischemia on atrial electrophysiology or the maintenance of AF. The previous data explained the ralationship between CAD and AF mainly through clinical, organic, tissue, and cellular level. The aim of our research is: (1) To study the influences of ischemia on soduim ion channel current(INa), calcium ion channel current(ICa), transient outward potassium current(Ito), action potential duration(APD), to analyse its cause and discuss its possible electrophysiological mechanism. (2) To observe the reaction of rabbit left and right atrial myocardium to ischemia, to analyse its possible effect on triggering arrhythmia.The animal of our study was New Zealand pure breed healthy white rabbit, weight 1.5-2.0 kg,male or female, provided by the animal laboratory of Medical Department, Peking university. The solution formula and current stimulative schem of our study refered to pertinent literature.The study included four parts.Part I: To study the influence of ischemia on INa of left and right atrial myocardial cells. We recorded INa from six left atrial myocardial cells and six INa of right atrial cells, observed the current changes and compared the discrepancy of mean current changes between left and right atrium after ischemic stimulation. The results revealed that: 1. The mean maxium INa current density of left atrium was 0.103±0.004nA...
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