title: Effect of oral levodopa and carbidopa on coronary spasm in variant angina pectoris.
abstract: The effect of oral administration of 500 mg of levodopa with 50 mg of carbidopa, a peripheral dopadecarboxylase inhibitor, on coronary vasomotion during vasoconstrictor stimuli was examined in 15 patients with variant angina presenting with hyperventilation-induced myocardial ischemia. Patients were studied during 3 noninvasive sessions and 1 angiographic session. In all sessions the basic protocol consisted of provocation of coronary spasm by hyperventilation before and 2 hours after levodopa and carbidopa administration. During angiography, great cardiac vein blood flow, right atrial and aortic pressures were measured, and coronary angiograms were recorded at baseline and 1 to 4 minutes after each hyperventilation. Samples for dopamine plasma levels were drawn before and throughout the studies. In 3 selected patients, levodopa and carbidopa were associated with 30 mg of domperidone, an antagonist of dopamine peripheral receptors. Levodopa and carbidopa consistently prevented the occurrence of ischemia after hyperventilation in 6 of the 15 patients. This was due to inhibition of local coronary spasm in 2 patients and reduced coronary constriction in 4. Ischemia due to hyperventilation was still prevented despite addition of domperidone with levodopa and carbidopa. Plasma dopamine levels were 23 +/- 15 before and 739 +/- 284 pg/ml 2 hours after administration of levodopa and carbidopa. These findings are consistent with either a decreased central dopaminergic activity and associated disregulation of vasomotor tone, or a peripheral vasodilatory effect of increasing dopamine.(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D000284:Administration, Oral; D000788:Angina Pectoris, Variant / Q000188:drug therapy*; D002230:Carbidopa / Q000008:administration & dosage / Q000627:therapeutic use*; D006328:Cardiac Catheterization; D017023:Coronary Angiography; D003329:Coronary Vasospasm / Q000188:drug therapy*; D004298:Dopamine / Q000502:physiology; D006801:Humans; D007980:Levodopa / Q000008:administration & dosage / Q000627:therapeutic use*; D013997:Time Factors
chemical_list: D007980:Levodopa; D002230:Carbidopa; D004298:Dopamine