Cinnamic acid lowers blood pressure and reverses vascular endothelial dysfunction in rats

Cinnamic acid (CA) possesses important cardiovascular effects such as cardioprotective, antiatherogenic, antihyperlipidemic and antioxidant, which predicts its potential role in the treatment of hypertension. The study was executed to investigate the antihypertensive potential of CA in Sprague Dawley (SD) rats followed by evaluation in diverse vascular preparations. Invasive blood pressure monitoring technique was used in normotensive and hypertensive rats, under anesthesia. Isolated aortic rings from rat and rabbit, Langendorrf's perfused isolated rabbit heart and guinea-pig right atria were used to probe the underlying mechanisms. The responses were recorded with pressure and force transducers connected to PowerLab Data Acquisition System. Intravenous administration of CA induced a respective 54% and 38% fall in mean arterial pressure (MAP) in the hypertensive and normotensive rats, respectively. In rat aortic rings, the CA exhibited muscarinic receptors-linked NO and indomethacin-sensitive endothelium-dependent (>50%) and calcium antagonistic and KATP-mediated endothelium-independent vasodilator effects. The CA showed negative inotropic and chronotropic effects in guinea-pig atrial strips. The CA suppressed force of ventricular contraction and heart rate while caused a 25% increase in coronary flow. This study supports the medicinal importance of CA as antihypertensive agent.