Interaminense Leylliane Fátima Leal, Jucá Davi Matthews, Magalhães Pedro Jorge Caldas, Leal-Cardoso José Henrique, Duarte Gloria Pinto, Lahlou Saad
Department of Physiology and Pharmacology, Federal University of Pernambuco, Recife-PE, Brazil.
Fundam Clin Pharmacol. 2007 Oct;21(5):497-506. doi: 10.1111/j.1472-8206.2007.00514.x.
Intravenous (i.v.) treatment of conscious DOCA-salt hypertensive rats with the essential oil of Ocimum gratissimum L. (Labiatae) (EOOG) induced a hypotensive effect that seems related to an active vascular relaxation rather than withdrawal of sympathetic tone. To corroborate this hypothesis, the present study examined the vascular effects of EOOG and its main constituent, eugenol (EUG) and the putative mechanisms underlying these effects. Additionally, the role of the vascular beta(2)-adrenergic mechanism in the mediation of EOOG-induced hypotension has also been investigated. In conscious DOCA-salt hypertensive rats, the EOOG-induced hypotension was reversible and remained unchanged by i.v. pretreatment with propranolol (2 mg/kg). In isolated aorta preparations with intact endothelium from DOCA-salt hypertensive rats, EOOG (1-1000 microg/mL) and EUG (0.006-6 mM) relaxed the phenylephrine-induced contraction similarly with IC(50) [geometric mean (95% confidence interval)] values of 226.9 (147.8-348.3) microg/mL and 1.2 (0.6-2.1) mm, respectively. Vasorelaxant effects of EOOG were significantly altered by removal of the vascular endothelium [IC(50) = 417.2 (349.5-497.8) microg/mL]. In a calcium-free medium, the CaCl(2)-induced contractions were significantly reduced and even abolished by EOOG at 300 and 1000 microg/mL, respectively, whereas EOOG (1000 microg/mL) did not have any significant effect on caffeine-induced contractions. Similar results were obtained with EUG (1.8 and 6 mM) on both CaCl(2)- and caffeine-induced contractions, respectively. The data suggest that hypotensive responses to EOOG in DOCA-salt hypertensive rats are due to an active vascular relaxation, which is partly dependent upon the integrity of the vascular endothelium and seems predominantly mediated through an inhibition of plasmalemmal Ca(2+) influx rather than Ca(2+)-induced Ca(2+) release from the sarcoplasmic reticulum.
用唇形科罗勒（Ocimum gratissimum L.）精油（EOOG）对清醒的去氧皮质酮盐高血压大鼠进行静脉注射治疗，可产生降压作用，这种作用似乎与血管主动舒张有关，而非交感神经张力的降低。为证实这一假说，本研究检测了EOOG及其主要成分丁香酚（EUG）的血管效应以及这些效应背后的潜在机制。此外，还研究了血管β₂-肾上腺素能机制在介导EOOG诱导的低血压中的作用。在清醒的去氧皮质酮盐高血压大鼠中，EOOG诱导的低血压是可逆的，静脉注射普萘洛尔（2 mg/kg）预处理后无变化。在去氧皮质酮盐高血压大鼠完整内皮的离体主动脉标本中，EOOG（1 - 1000 μg/mL）和EUG（0.006 - 6 mM）对去氧肾上腺素诱导的收缩具有相似的舒张作用，IC₅₀[几何均值（95%置信区间）]值分别为226.9（147.8 - 348.3）μg/mL和1.2（0.6 - 2.1）mM。去除血管内皮后，EOOG的血管舒张作用显著改变[IC₅₀ = 417.2（349.5 - 497.8）μg/mL]。在无钙培养基中，氯化钙诱导的收缩分别在300和1000 μg/mL的EOOG作用下显著降低甚至消失，而EOOG（1000 μg/mL）对咖啡因诱导的收缩无显著影响。EUG（1.8和6 mM）对氯化钙和咖啡因诱导的收缩也分别得到了类似结果。数据表明，去氧皮质酮盐高血压大鼠对EOOG的降压反应是由于血管主动舒张，这部分依赖于血管内皮的完整性，并似乎主要通过抑制质膜Ca²⁺内流而非肌浆网Ca²⁺诱导的Ca²⁺释放来介导。
