OBJECTIVE: To clarify whether endothelium derived nitric oxide contributes to exogenous bradykinin induced dilatation of human epicardial and resistance coronary arteries in vivo. DESIGN: Quantitative coronary angiography and Doppler flow velocity measurements were used to determine the effects of the nitric oxide synthesis inhibitor, NG-monomethyl-L-arginine (L-NMMA), on bradykinin induced dilatation of the epicardial and resistance coronary arteries. SETTING: Hiroshima University Hospital. PATIENTS: 20 patients (16 men and four women, mean (SD) age 56 (9) years) with angiographically normal smooth epicardial coronary arteries. INTERVENTIONS: Serial infusions of bradykinin (0.5, 1.5, and 2.5 micrograms/min) were given into the left coronary ostium before and after L-NMMA infusion (60 mumol/min). MAIN OUTCOME MEASURES: Epicardial coronary diameter, coronary blood flow, and coronary vascular resistance. RESULTS: Bradykinin-induced epicardial coronary vasodilatation after L-NMMA (dilatation by 2.5 micrograms/min, 3.8(1.4)% in the proximal and 5.9(1.8)% in the distal segments, mean (SEM)) was less (p < 0.001, respectively) than before L-NMMA (11.7(2.5)% and 15.1(2.0)%, respectively). In contrast, L-NMMA did not affect the bradykinin induced increase in coronary blood flow and decrease in coronary vascular resistance. CONCLUSIONS: Endothelium derived nitric oxide contributes to bradykinin induced dilatation of epicardial coronary arteries, but may be less important in coronary resistance vasodilatation.
OBJECTIVE: To clarify whether endothelium derived nitric oxide contributes to exogenous bradykinin induced dilatation of human epicardial and resistance coronary arteries in vivo. DESIGN: Quantitative coronary angiography and Doppler flow velocity measurements were used to determine the effects of the nitric oxide synthesis inhibitor, NG-monomethyl-L-arginine (L-NMMA), on bradykinin induced dilatation of the epicardial and resistance coronary arteries. SETTING: Hiroshima University Hospital. PATIENTS: 20 patients (16 men and four women, mean (SD) age 56 (9) years) with angiographically normal smooth epicardial coronary arteries. INTERVENTIONS: Serial infusions of bradykinin (0.5, 1.5, and 2.5 micrograms/min) were given into the left coronary ostium before and after L-NMMA infusion (60 mumol/min). MAIN OUTCOME MEASURES: Epicardial coronary diameter, coronary blood flow, and coronary vascular resistance. RESULTS:Bradykinin-induced epicardial coronary vasodilatation after L-NMMA (dilatation by 2.5 micrograms/min, 3.8(1.4)% in the proximal and 5.9(1.8)% in the distal segments, mean (SEM)) was less (p < 0.001, respectively) than before L-NMMA (11.7(2.5)% and 15.1(2.0)%, respectively). In contrast, L-NMMA did not affect the bradykinin induced increase in coronary blood flow and decrease in coronary vascular resistance. CONCLUSIONS: Endothelium derived nitric oxide contributes to bradykinin induced dilatation of epicardial coronary arteries, but may be less important in coronary resistance vasodilatation.
Authors: J H Reiber; P W Serruys; C J Kooijman; W Wijns; C J Slager; J J Gerbrands; J C Schuurbiers; A den Boer; P G Hugenholtz Journal: Circulation Date: 1985-02 Impact factor: 29.690