Effects of beta-adrenergic receptor stimulation on electrical and contractile activity in ventricular myocytes isolated from young adult and aged rat hearts

Cardiovascular Disease is one of the leading causes of death in Canada. The rising cost of health care and the increased incidence of cardiovascular disease are due, in large part, to the increased proportion of Canadians above the age of 65. However, despite the fact that most cardiovascular disease occurs in aging hearts, most research studies in disease models have focused on hearts from younger animals. The proposed studies will use 24 month old Fischer 344 rats, which are commonly used to model aging in humans. Hearts from aging animals have decreased sensitivity to adrenaline and this decreased sensitivity results in reduced cardiac output during periods of increased demand (i.e. during exercise). However, it is not clear whether the decreased sensitivity to adrenaline in the aged heart impacts upon the induction of abnormal heart rhythms by adrenaline. The proposed research will investigate potential changes in the cellular signaling pathway activated by adrenaline that occur with age in individual heart cells, as well as the functional consequences of these changes. The results of this study will improve our understanding of age-related changes in the response of the heart to situations such as stress and exercise, when circulating levels of adrenaline increase.