Exploring the interplay between extracellular pH and Dronedarone's pharmacological effects on cardiac function.

Dronedarone (DRN) is a clinically used drug to mitigate arrhythmias with multichannel block properties, including the sodium channel Na1.5. Extracellular acidification is known to change the pharmacological properties of several antiarrhythmic drugs.

β-Adrenergic receptor signalling pathway mediated antiarrhythmic activity of s-limonene in the rat heart.

S-Limonene (s-Lim) is a monocyclic monoterpene found in a variety of plants and has been shown to present antioxidant and cardioprotective activity in experimental models of myocardial infarction. The aim of this study was to evaluate the potential mechanism by which s-Lim exerts its antiarrhythmic effect, focusing on the blockade of β-adrenoceptor (β-AR) and its effects on various in vivo and in vitro parameters, including electrocardiogram (ECG) measurements, left ventricular developed pressure (LVDP), the β-adrenergic pathway, sarcomeric shortening and L-type calcium current (I). In isolated hearts, 10 μM of s-Lim did not alter the ECG profile or LVPD.

Status of β-Adrenoceptor Signal Transduction System in Cardiac Hypertrophy and Heart Failure.

Although -adrenoceptor ( -AR) signal transduction, which maintains cardiac function, is downregulated in failing hearts, the mechanisms for such a defect in heart failure are not fully understood. Since cardiac hypertrophy is invariably associated with heart failure, it is possible that the loss of -AR mechanisms in failing heart occurs due to hypertrophic process. In this regard, we have reviewed the information from a rat model of adaptive cardiac hypertrophy and maladaptive hypertrophy at 4 and 24 weeks after inducing pressure overload as well as adaptive cardiac hypertrophy and heart failure at 4 and 24 weeks after inducing volume overload, respectively.

Behavior of Hypertrophied Right Ventricle during the Development of Left Ventricular Failure Due to Myocardial Infarction.

In order to determine the behavior of the right ventricle, we have reviewed the existing literature in the area of cardiac remodeling, signal transduction pathways, subcellular mechanisms, β-adrenoreceptor-adenylyl cyclase system and myocardial catecholamine content during the development of left ventricular failure due to myocardial infarction. The right ventricle exhibited adaptive cardiac hypertrophy due to increases in different signal transduction pathways involving the activation of protein kinase C, phospholipase C and protein kinase A systems by elevated levels of vasoactive hormones such as catecholamines and angiotensin II in the circulation at early and moderate stages of heart failure. An increase in the sarcoplasmic reticulum Ca transport without any changes in myofibrillar Ca-stimulated ATPase was observed in the right ventricle at early and moderate stages of heart failure.

Experimental hypothyroidism induces cardiac arrhythmias and ranolazine reverts and prevents the phenotype.

Aims: Hypothyroidism is associated with an increased risk of cardiovascular disease and enhanced susceptibility to arrhythmias. In our investigation, we evaluated the potential involvement of late sodium current (I) in cardiac arrhythmias in an experimental murine model of hypothyroidism.

Main Methods: Male Swiss mice were treated with methimazole (0.

γ-Terpinene complexed with β-cyclodextrin attenuates spinal neuroactivity in animals with cancer pain by Ca2+ channel block.

Objectives: Considering that γ-terpinene (γ-TPN) is a monoterpene found in Cannabis oil, with high lipophilicity and limited pharmacokinetics, our objective was to evaluate whether its complexation in β-cyclodextrin (γ-TPN/β-CD) could improve its physicochemical properties and action on cancer pain, as well as verify the mechanisms of action involved.

Methods: The γ-TPN/β-CD was prepared and submitted to physicochemical characterization. Animals with sarcoma 180 were treated (vehicle, γ-TPN 50 mg/kg, γ-TPN/β-CD 5 mg/kg or morphine) and assessed for hyperalgesia, TNF-α and IL-1β levels, iNOS and c-Fos activity.

Resistance training improves cardiac function and cardiovascular autonomic control in doxorubicin-induced cardiotoxicity.

Doxorubicin (DOX) is an anticancer chemotherapy drug that is widely used in clinical practice. It is well documented that DOX impairs baroreflex responsiveness and left ventricular function and enhances sympathetic activity, cardiac sympathetic afferent reflexes and oxidative stress, which contribute to hemodynamic deterioration. Because resistance training (RT)-induced cardioprotection has been observed in other animal models, the objective of this study was to assess the effects of RT during DOX treatment on hemodynamics, arterial baroreflex, cardiac autonomic tone, left ventricular function and oxidative stress in rats with DOX-induced cardiotoxicity.

Topical application of (S)-(-)-limonene is as effective as phonophoresis for improving oxidative parameters of injured skeletal muscle in rats.

The aim of this study is to investigate the effects of limonene, alone or associated with therapeutic ultrasound, on oxidative stress following skeletal muscle injury. Thirty male Wistar rats were divided into 5 groups: CTR-control, MI-muscle injury without treatment, TPU-therapeutic pulsed ultrasound alone, TPU + LIM-phonophoresis with 5% limonene, and LIM-5% limonene applied topically. Muscle injury was induced by a mechanical abrupt impact over gastrocnemius muscle.

Nerol Attenuates Ouabain-Induced Arrhythmias.

Nerol (CHO) is a monoterpene found in many essential oils, such as lemon balm and hop. In this study, we explored the contractile and electrophysiological properties of nerol and demonstrated its antiarrhythmic effects in guinea pig heart preparation. Nerol effects were evaluated on atrial and ventricular tissue contractility, electrocardiogram (ECG), voltage-dependent L-type Ca current (I), and ouabain-triggered arrhythmias.

(-)-Terpinen-4-ol changes intracellular Ca handling and induces pacing disturbance in rat hearts.

(-)-Terpinen-4-ol is a naturally occurring plant monoterpene and has been shown to have a plethora of biological activities. The objective of this study was to investigate the effects of (-)-terpinen-4-ol on the rat heart, a key player in the control and maintenance of arterial blood pressure. The effects of (-)-terpinen-4-ol on the rat heart were investigated using isolated left atrium isometric force measurements, in vivo electrocardiogram (ECG) recordings, patch clamp technique, and confocal microscopy.

Dissection of the Effects of Quercetin on Mouse Myocardium.

Quercetin is a plant flavonoid with several biological activities. This study aimed to describe quercetin effects on contractile and electrophysiological properties of the cardiac muscle as well as on calcium handling. Quercetin elicited positive inotropism that was significantly reduced by propranolol indicating an involvement of the sympathetic nervous system.

Geraniol blocks calcium and potassium channels in the mammalian myocardium: useful effects to treat arrhythmias.

Geraniol is a monoterpene present in several essential oils, and it is known to have a plethora of pharmacological activities. In this study, we explored the contractile and electrophysiological properties of geraniol and its antiarrhythmic effects in the heart. The geraniol effects on atrial contractility, L-type Ca(2+) current, K(+) currents, action potential (AP) parameters, ECG profile and on the arrhythmia induced by ouabain were evaluated.

R(+)-pulegone impairs Ca²+ homeostasis and causes negative inotropism in mammalian myocardium.

The present study aimed to investigate the inotropic effects of R(+)-pulegone, a monoterpene found in plant species belonging to the genus Mentha, on the mammalian heart. In electrically stimulated guinea pig atria, R(+)-pulegone reduced the contractile force (~83%) and decreased the contraction time measured at 50% of the maximum force amplitude (CT(50)) from 45.8 ± 6.

Aqueous fraction from Costus spiralis (Jacq.) Roscoe leaf reduces contractility by impairing the calcium inward current in the mammalian myocardium.

Ethnopharmacological Relevance: Brazilian folk medicine uses infusion of Costus spiralis leaf to help people to treat arterial hypertension and syndromes of cardiac hyperexcitability.

Aim Of The Study: Evaluate the aqueous fraction (AqF) effect on atrial contractility and investigate its mechanism of action.

Materials And Methods: The AqF effect on the cardiac contractility was studied on isolated electrically driven guinea pig left atria.