Stimulation of Bradykinin B1 Receptors Induces Vasodilation in Conductance and Resistance Coronary Vessels in Conscious Dogs Comparison With B2 Receptor Stimulation

Background—Constitutive bradykinin B1 receptors have been identified in dogs; however, their physiological implications involving the coronary circulation remain to be determined. This study examined, in conscious dogs, the coronary response to des-Arg9-bradykinin (a B1 receptor agonist) and the mechanisms involved. Methods and Results—Eleven dogs were instrumented with a left ventricular micromanometer, a circumflex coronary catheter, a cuff occluder, a Doppler flow probe, and ultrasonic crystals to measure coronary blood flow velocity (CBFv) and coronary diameter (CD). Intracoronary des-Arg9-bradykinin (3 to 100 ng/kg) and bradykinin (0.1 to 10 ng/kg) did not modify systemic hemodynamics but dose-dependently increased CBFv and CD. Des-Arg9-bradykinin was less potent than bradykinin. Hoe 140 (a B2 antagonist, 10 μg/kg) abolished the effects of bradykinin but did not influence the effects of des-Arg9-bradykinin. When CBFv increase was prevented by the cuff occluder, CD responses to bradykinin and des-Arg9...