Autonomic nervous system and coronary blood flow changes related to emotional activation and sleep. Experimental models have been developed to investigate the influences of anger, fear, and sleep on coronary blood flow. Studies of anger in dogs with coronary stenosis indicate that the postarousal phase is particularly conducive to myocardial ischemia. Specifically, a delayed coronary vasoconstrictor response has been observed within 1-3 minutes after cessation of behavioral arousal. The response is prevented by bilateral stellectomy and can be elicited in anesthetized animals by electrical stimulation of the right or left stellate ganglion. The latter effect is averted by alpha-adrenergic blockade with prazosin. Although the basis for the protracted nature of the delayed vasoconstriction remains to be clarified, the current hypothesis is that the phenomenon results from a time-dependent imbalance between the vasoconstrictor effects of adrenergic input and the vasodilator influences of coronary pressure and/or cardiac metabolic activity. A behavioral model emulating the fear state has also been developed. When dogs that fail to exhibit anger are placed in a food-access confrontation protocol, the animals demonstrate a fearlike state evidenced by a cowering posture and somatic tremor. There is a distinct plasma catecholamine profile that is characterized by a predominant increase in epinephrine compared with norepinephrine. This is in contrast to the pattern observed during anger, in which a prevalent increase in norepinephrine is observed. Fear results in significant increases in heart rate, arterial blood pressure, and coronary arterial flow. Sleep is also associated with substantial alterations in coronary hemodynamic function. 