Effects of ticagrelor on the sodium/calcium exchanger 1 (NCX1) in cardiac derived H9c2 cells

An In Vivo Model of Estrogen Supplementation Concerning the Expression of Ca2+-Dependent Exchangers and Mortality, Vitality and Survival After Myocardial Infarction in Ovariectomized Rats

BACKGROUND

Ischemic-reperfusion damage of cardiomyocytes due to myocardial infarction (MI) often leads to the death of an individual. Premenopausal women have been observed to have a significantly lower risk of cardiovascular disease (CVD) than men of the same age. In menopausal women, this trend is significantly reversed, and the risk of CVD increases up to 10-fold. Estrogens affect the development and function of the heart muscle, and as they decrease, the risk and poor prognosis of CVD increase. This study is focused on the effects of estrogen supplementation on morbidity, vitality, and NCX1 expression after MI on a model system.

METHODS

In this study, female Sprague Dawley rats (n = 58), which were divided into three experimental groups (NN-control group, non-supplemented; OVX-N-ovariectomized, non-supplemented; OVX-S-ovariectomized, supplemented), received left thoracotomy in the fourth intercostal space. The left anterior descendent coronary artery was ligated 2 mm from its origin with an 8.0 suture. An immunohistological analysis as well as an RT-PCR analysis of NCX1 expression were performed.

RESULTS

A higher survival rate was recorded in the OVX-N group (86%) in comparison with the OVX-S group (53%) (p < 0.05). In addition, higher NCX1 expression 7 days/14 days after MI in the OVX-S group in comparison with the NN and OVX-N (p < 0.001 and p < 0.05) groups was recorded. Seven days after MI, a significantly higher expression (p < 0.005) of mRNA NCX1 in the OVX-N group was also recorded in comparison with the NN group.

CONCLUSIONS

This study provides a comprehensive description of the effect of estrogen supplementation on NCX1 expression and overall vitality in ovariectomized rats that survived MI.

Ticagrelor Can Regulate the Ion Channel Characteristics of Superior Cervical Ganglion Neurons after Myocardial Infarction

BACKGROUND

The superior cervical ganglion (SCG) plays a key role in cardiovascular diseases. The aim of this study was to determine the changes in the ion channel characteristics of the SCG following myocardial infarction (MI) and the role of pretreatment with the P2Y12 receptor antagonist ticagrelor (TIC).

METHODS

A total of 18 male rabbits were randomly divided into a control group, MI group, and P2Y12 receptor antagonist (TIC) group (abbreviated as the TIC group). Rabbit MI was performed via two abdominal subcutaneous injections of 150 mg·kg^-1·d^-1 of isoproterenol (ISO) with an interval of 24 h. TIC pretreatment at 20 mg·kg^-1·d^-1 was administered via gavage for two consecutive days. The cardiac function of each group was evaluated with echocardiography. ADP receptor P2Y12 expressions in SCGs were determined using RT-PCR and immunofluorescence staining. Ion channel characteristics of SCG neurons were measured using a whole-cell patch clamp. Intracellular calcium concentrations for SCG neurons were measured using confocal microscopy.

RESULTS

Cardiac function was reduced in the rabbits of the MI group, the sympathetic nerve activity of SCGs was increased, and the current amplitude of the neuron ion channel was increased. MI led to alterations in the activation and inactivation characteristics of I_Na channels accompanied by increased expression of P2Y12 in SCGs. Most of these abnormalities were prevented by TIC pretreatment in the TIC group.

CONCLUSIONS

TIC pretreatment could attenuate the increase in P2Y12 expression in SCGs and the changes to the ion channel characteristics of SCG neurons after MI. This may be the mechanism underlying the cardiac protective effects of TIC.

Ticagrelor alleviates high-carbohydrate intake induced altered electrical activity of ventricular cardiomyocytes by regulating sarcoplasmic reticulum-mitochondria miscommunication

Metabolic syndrome (MetS) is associated with additional cardiovascular risk in mammalians while there are relationships between hyperglycemia-associated cardiovascular dysfunction and increased platelet P2Y12 receptor activation. Although P2Y12 receptor antagonist ticagrelor (Tica) plays roles in reduction of cardiovascular events, its beneficial mechanism remains poorly understood. Therefore, we aimed to clarify whether Tica can exert a direct protective effect in ventricular cardiomyocytes from high-carbohydrate diet-induced MetS rats, at least, through affecting sarcoplasmic reticulum (SR)-mitochondria (Mit) miscommunication. Tica treatment of MetS rats (150 mg/kg/day for 15 days) significantly reversed the altered parameters of action potentials by reversing sarcolemmal ionic currents carried by voltage-dependent Na+ and K+ channels, and Na+/Ca2+-exchanger in the cells, expressed P2Y12 receptors. The increased basal-cytosolic Ca2+ level and depressed SR Ca2+ load were also reversed in Tica-treated cells, at most, though recoveries in the phosphorylation levels of ryanodine receptors and phospholamban. Moreover, there were marked recoveries in Mit structure and function (including increases in both autophagosomes and fragmentations) together with recoveries in Mit proteins and the factors associated with Ca2+ transfer between SR-Mit. There were further significant recoveries in markers of both ER stress and oxidative stress. Taken into consideration the Tica-induced prevention of ER stress and mitochondrial dysfunction, our data provided an important document on the pleiotropic effects of Tica in the electrical activity of the cardiomyocytes from MetS rats. This protective effect seems through recoveries in SR-Mit miscommunication besides modulation of different sarcolemmal ion-channel activities, independent of P2Y12 receptor antagonism.

Ticagrelor resistance: a case series and algorithm for management of non-responders

The placement of cervical and intracranial stents requires the administration of antiplatelet drugs to prevent thromboembolic complications. Ticagrelor has emerged as the most widely used alternative in clopidogrel non-responders owing to its potent antiplatelet effects. Because ticagrelor does not require hepatic activation, many neurointerventionalists choose to forgo laboratory testing of platelet inhibition. In rare instances, patients may not achieve adequate platelet inhibition following ticagrelor administration. In this paper we review the mechanism of action of ticagrelor and its use in cerebrovascular procedures. We present two cases of ticagrelor non-responsiveness from two high-volume cerebrovascular centers, discuss their management, and propose an algorithm for managing ticagrelor non-responsiveness.

Validation of an HPLC-MS/MS Method for the Determination of Plasma Ticagrelor and Its Active Metabolite Useful for Research and Clinical Practice

Ticagrelor is an antiplatelet agent which is extensively metabolized in an active metabolite: AR-C124910XX. Ticagrelor antagonizes P2Y12 receptors, but recently, this effect on the central nervous system has been linked to the development of dyspnea. Ticagrelor-related dyspnea has been linked to persistently high plasma concentrations of ticagrelor. Therefore, there is a need to develop a simple, rapid, and sensitive method for simultaneous determination of ticagrelor and its active metabolite in human plasma to further investigate the link between concentrations of ticagrelor, its active metabolite, and side effects in routine practice. We present here a new method of quantifying both molecules, suitable for routine practice, validated according to the latest Food and Drug Administration (FDA) guidelines, with a good accuracy and precision (<15% respectively), except for the lower limit of quantification (<20%). We further describe its successful application to plasma samples for a population pharmacokinetics study. The simplicity and rapidity, the wide range of the calibration curve (2–5000 µg/L for ticagrelor and its metabolite), and high throughput make a broad spectrum of applications possible for our method, which can easily be implemented for research, or in daily routine practice such as therapeutic drug monitoring to prevent overdosage and occurrence of adverse events in patients.

Effects of ticagrelor pretreatment on electrophysiological properties of stellate ganglion neurons following myocardial infarction

Higher sympathetic activity predisposes to malignant ventricular arrhythmias in the context of myocardial infarction (MI). This is, in part, mediated by the electrical activity of the stellate ganglion (SG). The aim of this study is to examine the effects of ticagrelor pretreatment on the electrophysiological properties of SG neurons following MI in rabbits. MI was induced by isoproterenol (ISO) of 150 mg kg-1 d-1 (twice at an interval of 24 hours). Ticagrelor pretreatment was administered at low- (10 mg kg-1 d-1) or high-dose (20 mg kg-1 d-1). Protein and RNA expression were determined by immunohistochemical analysis and real-time PCR, respectively. The activity of sodium channel current (INa), delayed rectifier potassium current (IKDR), M-type potassium current (IKM) as well as action potentials (APs) from SG neurons were measured by whole-cell patch-clamp. Intracellular calcium concentrations were measured by confocal microscopy. Compared with the control group, the MI group exhibited a greater amplitude of INa, IKDR and IKM, significantly altered activation and inactivation characteristics of INa, no significant alterations in protein or mRNA expression of sodium and M-type potassium channels, along with higher AP amplitude and frequency and intracellular calcium concentrations. Most of these abnormalities were prevented by pretreatment with low- or high-dose ticagrelor. Our data suggest that ticagrelor exerts cardioprotective effects, potentially through modulating the activity of different ion channels in SG neurons.