Coronary endothelial vasodilator dysfunction: clinical relevance and therapeutic implications

Endothelial function of epicardial arteries and coronary resistance vessels, as well as endothelial dysfunction and clinical symptoms of coronary artery disease and their therapeutic implications are reviewed including the presentation of the author's own results. Coronary endothelial vasodilator dysfunction represents a fundamental functional disturbance in vascular biology with the development of atherosclerosis. This functional alteration in coronary vascular reactivity appears to play an important integral part in the clinical presentation of coronary artery disease. Humoral and neuronal factors in favour of vasoconstrictor influences affect the balance between myocardial oxygen supply and demand, thus, facilitating the manifestation of myocardial ischemia. In order to identify more selective therapies the potential mechanisms underlying an impaired release or activity of EDRF/NO must be considered. Dysfunction of the endothelial L-arginine/NO pathway may involve decreased activity of NO synthase, increased inactivation of NO formed from its precursor L-arginine, impaired signal transduction mechanisms and reduced intracellular availability of L-arginine. Currently, initial therapeutic strategies include the supplementation of L-arginine, the use of antioxidants, as well as ACE-inhibitors. ACE-inhibitors have been shown not only to reduce vascular tone (and hypertrophy) by inhibition of angiotensin II formation, but also by increasing the endothelial production of NO and prostacyclin most likely due to the local accumulation of endothelium-derived bradykinin. Thus, ACE-inhibition appears to provide the potential to improve endothelial NO synthesis. Indeed, study results demonstrate that chronic ACE-inhibition is associated with an increased coronary blood flow response to acetylcholine suggesting an improvement in endothelial vasodilator functioning of coronary resistance vessels.(ABSTRACT TRUNCATED AT 250 WORDS)