ABSTRACT
The principle factors regulating coronary blood flow include myocardial metabolism, circulating vasoactive agents, direct neural effects, myogenic influences, and autoregulation. Metabolic vasodilator stimuli are generally the predominant determinants of coronary vascular resistance. This chapter defines central nervous system sites capable of producing coronary vasoconstriction upon activation. It evaluates the mechanism of the central coronary constrictor response, and searches for selective coronary vasomotor responses during central activation. Electrical activation of the stellate ganglion, emotional stress, and reflex activation of the sympathetic nervous system produce direct neurally mediated coronary constriction. The coronary blood flow response to activation of the sympathetic nerves innervating the coronary vessels may be dramatically altered in two situations: first, neural activation in conscious animals elicits an augmented coronary response; second, the coronary vasomotor response to adrenergic stimulation is much more pronounced in the presence of a coronary stenosis. Under certain pathologic circumstances, neural factors may exert a critical influence on coronary blood flow.
