Cardiovascular Effects of the Essential Oil of Croton argyrophylloides in Normotensive Rats: Role of the Autonomic Nervous System

Abstract

Cardiovascular effects of the essential oil of Croton argyrophylloides Muell. Arg. (EOCA) were investigated in normotensive rats. In saline-pretreated anesthetized or conscious rats, intravenous (i.v.) injection of the EOCA induced dose-dependent hypotension. Dose-dependent tachycardia was observed only in conscious rats. In anesthetized rats, cervical bivagotomy failed to enhance EOCA-induced hypotension but unmasked significant bradycardia. In conscious rats, i.v. pretreatment with methylatropine, but not with atenolol or L-NAME, reduced both hypotensive and tachycardiac responses to EOCA. However, hexamethonium pretreatment reverted the EOCA-induced tachycardia into significant bradycardia without affecting the hypotension. In aortic ring preparations precontracted with phenylephrine, EOCA induced a concentration-dependent relaxation that was significantly reduced by vascular endothelium removal and pretreatment with atropine, indomethacin, or glibenclamide but remained unaffected by pretreatment with L-NAME or TEA. It is concluded that i.v. treatment with EOAC decreased blood pressure probably through an active vascular relaxation rather than withdrawal of sympathetic tone. Muscarinic receptor stimulation, liberation of the endothelium-derived prostacyclin, and opening KATP channels are partially involved in the aortic relaxation induced by EOCA and in turn in the mediation of EOCA-induced hypotension. EOCA-induced tachycardia in conscious rats appears to be mediated reflexly through inhibition of vagal drive to the heart.

Cardiovascular Effects of Trans-4-Methoxy-β-Nitrostyrene in Spontaneously Hypertensive Rats: Comparison With Its Parent Drug β-Nitrostyrene

“…This arterial catheter allows us to record the arterial blood pressure. For systemic drug administration, the inferior vena cava was cannulated through the left femoral vein as previously described (Alves-Santos et al, 2016). After surgical procedure, all animals received an intramuscular injection of penicillin (24,000 IU), then housed individually in plastic cages and allowed to recover for 24 h before any circulatory experiments.…”

Therapeutic application of herbal essential oil and its bioactive compounds as complementary and alternative medicine in cardiovascular-associated diseases

“…Likewise, P. asiatica EO also modulated mRNA and protein expression of LDL receptor and HMG-CoA reductase in HepG2 cells [31]. [32][33][34][35][36][37]. Particularly, C. argyrophylloides EO induced a dosedependent aortic relaxation (IC 50 , ~25 μg/mL) that was associated with muscarinic receptor stimulation as well as liberation of the endotheliumderived prostacyclin whereby in experimented condition, its activity was greatly lowered by pre-treatment with anti-muscarinic agent (e.g 1 μM atropine, IC 50 increase to ~197 μg/mL) [36].…”

“…[32][33][34][35][36][37]. Particularly, C. argyrophylloides EO induced a dosedependent aortic relaxation (IC 50 , ~25 μg/mL) that was associated with muscarinic receptor stimulation as well as liberation of the endotheliumderived prostacyclin whereby in experimented condition, its activity was greatly lowered by pre-treatment with anti-muscarinic agent (e.g 1 μM atropine, IC 50 increase to ~197 μg/mL) [36]. Its action was also affected by cyclooxygenase blocker (e.g at 10 μM indomethacin, IC 50 increase to ~91 μg/mL), vascular endothelium removal (at IC 50 increase to ~76 μg/mL) and anti-diabetic agent (e.g at 100 μM glibenclamide, IC 50 increase to ~64 μg/mL) [36].…”

“…In rat endothelium intact aorta preparations, A. canelilla bark EOs (1-600 μg/mL) and C. zehntneri EO (1-1000 μg/mL) induced a dose-related reduction of K + (60 mM)-stimulated contraction [IC 50 , ~65 and 202 μg/mL respectively)], an effect that was substantially reduced by treatment of high dose of atropine ( EOs -induced relaxation was also partly linked to the opening of potassium (K + ) adenosine triphosphate (K-ATP)-channel which resulted in its hypotensive effect [36]. Mentha x villosa EO (10-500 μg/mL) and 1,8cineole (C 10 H 18 O) (0.006-2.6 mM) also antagonize the effect of potassium ions (60-80 mM) stimulated contractions (IC 50 , ~165 μg/ml) [39,42,45].…”

“…However, hypotensive effect of A. zerumbet EOs was much lower than that of its pure bioactive terpinen-4ol at same doses (1-10 mg/kg) [34,35]. In either experimented deoxycorticosterone-acetate (DOCA)-salt hypertensive or normotensive conscious rat, the effect of A. zerumbet EO, C. zehntneri EO, C. argyrophylloides EO, C. nepetaefolius EO (1 to 50 mg/kg), O. gratissimum EO, N. sativa oil, terpinen-4-ol and 1,8-cineole on hemodynamic parameters can be seen with reduction of mean aortic pressure, heart rate and arterial blood pressure [34,36,40,41,[61][62][63]. These hypotension evidences on hemodynamic parameters of such EOs (e.g A. canelilla, A. zerumbet, C. argyrophylloides and terpinen-4ol) were mainly caused by active vascular relaxation in lieu to the withdrawal of nervous system sympathetic activity [34,36].…”