Changes in myocardial thiamine in arteriosclerotic and non-arteriosclerotic rats subjected to isoprenaline induced myocardial infarction.

Thiamine is essential for myocardial aerobic metabolism and contractural energy. Changes in myocardial thiamine during the acute stages of isoprenaline (isoproterenol) induced infarction were investigated using male and female breeder rats with well established arteriosclerosis vs male and female virgin rats with normal arteries. Paradoxically, the arteriosclerotic rats survived better and manifested less untoward signs of acute myocardial ischaemia than the non-arteriosclerotic rats. Male rats developed much more severe myocardial necrosis than female rats and concomitantly exhibited significantly greater reduction in myocardial thiamine during acute ischaemia compared with female subjects. The greatly reduced cardiac thiamine stores in the male subjects as well as in the non-arteriosclerotic subjects is indicative of the deterioration of their capacity to affect adequate cardiac oxidative energy metabolism and is in keeping with their manifestion of much more severe pathophysiological changes during the course of acute myocardial ischaemia. Either the preexisting arterial disease in the breeder rats affords the development of protective extracollateral coronary circulation or there is less cardiac embarrassment due to vital cardiac thiamine loss in arteriosclerotic animals, or the decreased availability of thiamine affects the production of vital adrenal steroids in a different manner in arteriosclerotic vs non-arteriosclerotic rats.