Studies of the physiological and pathophysiological characteristics of the stable hypertrophied heart will be pursued. Particular attention is paid to the studies of the coronary blood flow and its regional distribution in hypertrophy, as well as the effects of stress, anemia, and pharmacologic agents on flow and distribution. Scintigraphic studies with Thallium uptake during hypertrophy as well as with regression of hypertrophy are to be characterized, and segmental function in the hypertrophied myocardium at rest and under stress is to be defined. Estimation of myocardial blood flow by hydrogen polarographic technique, developed in our laboratory, will be pursued and compared with other means of measuring or estimating myocardial blood flow, in particular microspheres and electromagnetic methods. This would serve to define the limitations and advantages of the polarographic technique and its performance under various conditions with an aim to its application in chronic conscious animals. Such application has been instituted in our laboratory, and has proven to have a tremendous practical value. Further studies to evaluate the meaning of heart rate pressure product as an index of myocardial oxygen consumption in normal and hypertrophied hearts will also be pursued.