Relaxant effects of β-Citronellol in isolated aortic or tracheal rings of rats
β-Citronellol (βCT) is a constituent found in the essential oil of Cymbopogon citratus. Here, we investigated the relaxant effects of βCT on vascular (aorta) or non-vascular (trachea) smooth muscle preparations obtained from rats. Trace recordings were obtained isometrically. βCT (1–1000µM) had no measurable effects on trace recordings of aortic or tracheal preparations under resting tone conditions. βCT fully relaxed aortic rings contracted by 60 mM K+ whereas it relaxed just partially (˜70%) the phenylephrine (PHE, 1µM)-induced contractions. Values of IC50 were 255.7±55 (n=6) and 356.15±79.5 (n=5)µM, respectively, which did not reach significant difference (p>0.05) when compared one another. In tracheal preparations, βCT fully relaxed as 60 mM K+- as carbachol (CCh)-induced contractions with a similar pharmacological potency (IC50 values were 111.3±25.2 [n=6] and 174.4±32.0 [n=6] µM, respectively). In tracheal tissues under Ca2+-free conditions, βCT (200µM, n=6) impaired the contractions induced by exogenous addition of Ba2+ (0.1–50 mM), an exclusive voltage-operated Ca2+ channel (VOCC) permeable ion, in preparations depolarized by K+ (60 mM). In aortic tissues, βCT (200µM, n=6) did not change Ba2+-induced contractions under similar conditions. Thus, βCT has relaxant properties in aortic or tracheal smooth muscle preparations and it seems likely that βCT behaves as a VOCC blocker in tracheal tissues, but not in aortic rings.