Linalool-rich rosewood oil evoked a vago-vagal bradycardic and depressor effect in normotensive rats

Cardiovascular effects of the linalool-rich essential oil of Aniba rosaeodora (EOAR or rosewood) in normotensive rats were investigated. Male Wistar rats were anesthetized and two catheters were implanted for blood pressure recording and drug injection. In anesthetized rats, intravenous (i.v.) EOAR elicited dose-dependent hypotensive and bradycardiac effects which were characterized in two periods (phases 1 and 2). The first rapid component (phase 1) evoked by EOAR was abolished by bilateral vagotomy, perineural treatment of both cervical vagus nerves with capsaicin and was absent after left ventricle injection. However, i.v. pretreatment with capsazepine, ondansetron or HC030031 did not alter phase 1 of the cardiovascular responses to EOAR. In conscious rats, EOAR evoked rapid hypotensive and bradycardiac (phase 1) effects that were abolished by i.v. methylatropine. EOAR induces a vago-vagal bradycardiac and depressor reflex (phase 1) that apparently results from the stimulation of vagal pulmonary rather than cardiac C-fiber afferents and does appear to involve activation of neither the 5HT₃ receptors nor the two chemosensory ion channels TRPV₁ and TRPA₁ receptors. The phase 2 hypotensive response to EOAR seems to result from a direct vasodilatory effect since EOAR relaxed phenylephrine-induced contractions in rat isolated aortic rings.