Calcium Channel Blocker Verapamil Research Articles

Role of L-type Ca2+ channels in the differential response to oxytocin of uteri from virgin and proven breeder rats

Introduction: The experience of pregnancy affects uterine function well beyond delivery. For instance, the likelihood of accelerated parturitions, spontaneous delivery, and risk of hemorrhage in future pregnancies is increased with parity. While epidemiological evidence for these phenomena is abundant, mechanistic explanations of these and other changes are still being investigated. We previously demonstrated that the response to oxytocin is more robust in the uteri of proven breeder rats and that T-type calcium channels, although slightly more expressed in proven breeder samples had a rather limited impact in this mechanism. Hypothesis: Here, we tested the hypothesis that voltage gated L-type calcium channels contribute more significantly than T-type calcium channels in the differential response to oxytocin in the myometrium from virgin (V) and proven breeder (PB) rats. Methods: V and PB non pregnant female 18-week-old rats were euthanized at proestrus. Uterine strips were suspended in a tissue bath containing Krebs solution (in mM, NaCl 117, KCl 4.7, NaHCO3 25, MgCl2 1.2, KH2PO4 1.2, CaCl2 2.5, glucose 11, pH= 7.4) at 37°C in 95% O2 and 5% CO2. Dose response curves to the L-type calcium channel blocker Verapamil (10E-8 to 10E-5 M) and dose responses to oxytocin in the presence of either 10 E-6 or 10E-5 Verapamil were recorded. Area under the curve, frequency, amplitude, and duration of contractions were measured. L-type channels expression was evaluated with qRT-PCR. T-tests and ANOVA two ways were used for statistical analysis. Results: Compared to control, both doses of Verapamil suppressed 100% of spontaneous and 50% of oxytocin-evoked contractility in V and PB samples. The maximal response to oxytocin was significantly stronger in PB than in V (p<0.001). Thus, blocking L-type Ca2+ channels does not alter the differential response to oxytocin observed in the absence of verapamil. The difference in Expression of the L-type calcium channel revealed a 2-fold increase in PB compared to V uteri. These findings closely align with oxytocin dose response data in the presence of the T-type calcium channels blocker Mibefradil and with the T-type channels expression. Conclusions: Neither L-type or T-type Ca2+ channels appear to be key players in the differential response to oxytocin of V and PB uteri. Instead, it is more likely that other elements of the intracellular calcium control are involved in this phenomenon. Acknowledgements: This study was supported by a Kenneth Suarez Fellowship to RP and an MWU intramural fund to MP. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Calcium channel inhibitor and extracellular calcium improve aminoglycoside-induced hair cell loss in zebrafish.

Aminoglycosides are commonly used antibiotics for treatment of gram-negative bacterial infections, however, they might act on inner ear, leading to hair-cell death and hearing loss. Currently, there is no targeted therapy for aminoglycoside ototoxicity, since the underlying mechanisms of aminoglycoside-induced hearing impairments are not fully defined. This study aimed to investigate whether the calcium channel blocker verapamil and changes in intracellular & extracellular calcium could ameliorateaminoglycoside-induced ototoxicity in zebrafish. The present findings showed that a significant decreased number of neuromasts in the lateral lines of zebrafish larvae at 5days' post fertilization after neomycin (20μM) and gentamicin (20mg/mL) exposure, which was prevented by verapamil. Moreover, verapamil (10-100μM) attenuated aminoglycoside-induced toxic response in different external calcium concentrations (33-3300μM). The increasing extracellular calcium reduced hair cell loss from aminoglycoside exposure, while lower calcium facilitated hair cell death. In contrast, calcium channel activator Bay K8644 (20μM) enhanced aminoglycoside-induced ototoxicity and reversed the protective action of higher external calcium on hair cell loss. However, neomycin-elicited hair cell death was not altered by caffeine, ryanodine receptor (RyR) agonist, and RyR antagonists, including thapsigargin, ryanodine, and ruthenium red. The uptake ofneomycininto hair cells was attenuated by verapamil and under high external calcium concentration. Consistently, the production of reactive oxygen species (ROS) in neuromasts exposed to neomycin was also reduced by verapamil and high external calcium. Significantly, zebrafish larvae when exposed to neomycin exhibited decreased swimming distances in reaction to droplet stimulus when compared to the control group. Verapamil and elevated external calcium effectively protected the impaired swimming ability of zebrafish larvae induced by neomycin. These data imply that prevention of hair cell damage correlated with swimming behavior against aminoglycoside ototoxicity by verapamil and higher external calcium might be associated with inhibition of excessive ROS production andaminoglycoside uptake through cation channels. These findings indicate that calcium channel blocker and higher external calcium could be applied to protect aminoglycoside-induced listening impairments.

Continuous direct intraarterial treatment of meningitis-induced vasospasm in a pediatric patient: illustrative case.

Bacterial meningitis-induced ischemic stroke continues to cause significant long-term complications in pediatric patients. The authors present a case of severe right internal carotid artery terminus and M1 segment vasospasm in a 9-year-old with an infected cholesteatoma, which was refractory to multiple intraarterial treatments with verapamil and milrinone. This is the first report of continuous intraarterial antispasmodic treatment in a pediatric patient as well as the first report of continuous treatment in an awake and extubated patient. Arterial narrowing was successfully treated by continuous direct intraarterial administration of both a calcium channel blocker (verapamil) and a phosphodiesterase-3 inhibitor (milrinone). The patient recovered remarkably well and was discharged home with no neurological deficit (National Institutes of Health Stroke Scale score 0) and ambulatory without assistance after 22 days. The authors report a promising outcome of this technique performed in a pediatric patient. This represents a novel treatment option for the prevention of stroke in pediatric bacterial meningitis. Continuous, direct intraarterial administration of antispasmodic medications can successfully prevent long-term neurological deficit in pediatric meningitis-associated vasospasm. The described method has the potential to significantly improve outcomes in severe pediatric meningitis-associated vasospasm.

Verapamil mitigates chloride and calcium bi-channelopathy in a myotonic dystrophy mouse model.

Myotonic dystrophy type 1 (DM1) involves misregulated alternative splicing for specific genes. We used exon or nucleotide deletion to mimic altered splicing of genes central to muscle excitation-contraction coupling in mice. Mice with forced skipping of exon 29 in the CaV1.1 calcium channel combined with loss of ClC-1 chloride channel function displayed markedly reduced lifespan, whereas other combinations of splicing mimics did not affect survival. The Ca2+/Cl- bi-channelopathy mice exhibited myotonia, weakness, and impairment of mobility and respiration. Chronic administration of the calcium channel blocker verapamil rescued survival and improved force generation, myotonia, and respiratory function. These results suggest that Ca2+/Cl- bi-channelopathy contributes to muscle impairment in DM1 and is potentially mitigated by common clinically available calcium channel blockers.

FRESH™ 3D bioprinted cardiac tissue, a bioengineered platform for in vitro pharmacology.

There is critical need for a predictive model of human cardiac physiology in drug development to assess compound effects on human tissues. In vitro two-dimensional monolayer cultures of cardiomyocytes provide biochemical and cellular readouts, and in vivo animal models provide information on systemic cardiovascular response. However, there remains a significant gap in these models due to their incomplete recapitulation of adult human cardiovascular physiology. Recent efforts in developing in vitro models from engineered heart tissues have demonstrated potential for bridging this gap using human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) in three-dimensional tissue structure. Here, we advance this paradigm by implementing FRESH™ 3D bioprinting to build human cardiac tissues in a medium throughput, well-plate format with controlled tissue architecture, tailored cellular composition, and native-like physiological function, specifically in its drug response. We combined hiPSC-CMs, endothelial cells, and fibroblasts in a cellular bioink and FRESH™ 3D bioprinted this mixture in the format of a thin tissue strip stabilized on a tissue fixture. We show that cardiac tissues could be fabricated directly in a 24-well plate format were composed of dense and highly aligned hiPSC-CMs at >600 million cells/mL and, within 14 days, demonstrated reproducible calcium transients and a fast conduction velocity of ∼16 cm/s. Interrogation of these cardiac tissues with the β-adrenergic receptor agonist isoproterenol showed responses consistent with positive chronotropy and inotropy. Treatment with calcium channel blocker verapamil demonstrated responses expected of hiPSC-CM derived cardiac tissues. These results confirm that FRESH™ 3D bioprinted cardiac tissues represent an in vitro platform that provides data on human physiological response.

Artemisinin combined with low dose quinidine suppresses ventricular tachyarrhythmia in a model of Brugada syndrome

Abstract Background The mechanism of Brugada syndrome (BrS) is unclear. One of the mechanisms has been suggested that uneven dispersion of Ito channel between epicardium and endocardium induced ventricular arrhythmia. Artemisinin, which originates from a Chinese herb and is used widely as an antimalarial drug, is reported to inhibit the Ito channel in a canine experimental model previously. Objective We aimed to investigate the effect of artemisinin, alone and in combination with low dose quinidine, on the suppression of ventricular tachyarrhythmia in BrS in a canine experimental model. Methods We recorded transmural pseudo-ECG and epicardial/endocardial action potentials (APs) from coronary-perfused canine right ventricular wedge preparation. We used acetylcholine (3 μM), calcium channel blocker verapamil (1 μM), and Ito agonist NS5806 (6 – 10 μM) to mimic the BrS model. We induced ventricular arrhythmia and then perfused low dose quinidine (1 – 2 μM) alone and additionally perfused artemisinin (100 – 150 μM) to suppress the arrhythmia. We evaluated ventricular arrhythmia inducibility and measured AP duration, J wave area, notch index, and T wave dispersion. Results The provocation agents induced prominent J wave in all sample models. In 6 sample models out of 8 for artemisinin alone group, ventricular arrhythmia was induced. Artemisinin suppressed ventricular arrhythmia and recovered the AP dome in all preparations. J wave area and epicardial notch index were also decreased after artemisinin perfusion. The low dose quinidine (1 – 2 μM) did not completely suppressed the ventricular arrhythmia in 6 out of 6 sample models. However, additional artemisinin (100 – 200 μM) infusion suppressed the ventricular arrhythmia in all sample models and restored the AP dome. J wave area and epicardial notch index were also decreased. Conclusions Our findings suggest that artemisinin can alleviate ventricular arrhythmia in the BrS wedge preparation model. Combining artemisinin with low dose quinidine may further suppress ventricular arrhythmia by inhibiting potassium channels, including Ito channel. Artemisinin might reduce the therapeutic dose of quinidine by additional inhibition of potassium channels.

Abstract 17335: Novel Functional Genomic Studies in Scn1bb Variant Associated With Brugada Syndrome and the Ameliorative Effect of Acacetin

Background: Brugada syndrome (BrS) is a channelopathy associated with the development of life-threatening ventricular tachycardia and fibrillation (VT/VF). At present, pharmacological approaches to therapy are very limited. Objective: To evaluate the effect of an SCN1Bb variant and the effects of acacetin in experimental models of BrS. Methods: We evaluated the effect of acacetin in: 1) HEK293 cells expressing Kv4.3+ KChIP2 and Nav1.5+ SCN1B using patch clamp techniques (22 O C), 2) canine ventricular epicardial myocytes 3) coronary-perfused canine right (RV) preparations and 4) Langendorff-perfused canine whole-heart models of BrS in which the sodium channel blocker ajmaline or the calcium channel blocker verapamil, together with the transient outward current agonist NS5806 were used to provoke the arrhythmic phenotype. Results: Co-expression of SCN5A -WT+ KCND3-WT with KChIP2 + SCN1Bb -R214Q (variant associated with 3 cases of BrS and 1 case of sudden infant death (SIDS)), resulted in a 210% increase in total charge of the transient outward potassium current (I to ) as well as a 56.5% reduction in sodium channel current (I Na ) when compared to SCN1Bb-WT . In the absence of the mutation, acacetin inhibited I to with an IC 50 of 7.2±1.0 μM (n=3) in HEK cells, similar to the value obtained in native epicardial myocytes (6 μM). In the presence of the SCB1Bb mutant, IC 50 was dramatically reduced to 2.6±1 μM (n=5, p<0.05) Mean ±SEM. In the wedge and whole-heart models of BrS, acacetin dose-dependently reduced the epicardial action potential notch recorded from the RV or RVOT. Acacetin (5-10 μM) totally suppressed the electrocardiographic and arrhythmic manifestation of BrS, regardless of the pharmacologic model used to induce the arrhythmic phenotype. All repolarization defects were reversed, resulting in marked diminution of J waves leading to total suppression of VT/VF. Conclusions: Our findings demonstrate the ability of an SCN1Bb variant to dramatically shift the balance of current in the early phases of the RV epicardial action potential by reducing I Na as well as augmenting I to , thus predisposing to the development of the BrS phenotype. Our observations also hold promise for acacetin as a safe and effective pharmacologic treatment for BrS and some cases of SIDS.

Study on the effect and mechanism of verapamil on the growth of human airway granulosa fibroblasts

Objective: This study aimed to investigate the inhibitory effect of the calcium channel blocker verapamil on human airway sarcomeric fibroblasts through network pharmacology molecular docking combined with experimental validation, so as to provide a theoretical and experimental basis for clinical use of calcium channel blockers against benign airway stenosis. Methods: The relevant targets of verapamil, airway injury, sarcoidosis and fibroblast were collected and intersected by a public database, respectively. The protein-protein interaction network was constructed by combining STRING; the DAVID database was used for gene function GO and KEGG pathway enrichment analysis. Molecular docking validation of verapamil and key targets was performed using AutoDock. Meanwhile, human lung bronchial tissue and human airway granulation tissue were treated with different antibiotic regimens to prevent contamination, in which human normal airway fibroblasts were treated with 92.81 μg/ml verapamil, while airway granulosa fibroblasts were treated with 69.57 μg/ml verapamil. The flow cytometry test was performed to detect the apoptotic effect of verapamil on human airway granulosa fibroblasts. The relative expression of mRNA of relevant factors between human normal airway fibroblasts and human airway granulosa fibroblasts was detected using polymerase chain reaction (PCR). Meanwhile, the difference in mRNA expression between human airway fibroblasts in normal and disease conditions was measured by PCR, and the change in mRNA expression of related factors after treatment with verapamil was determined to verify the findings of network pharmacology analysis. Results: This study predicted that verapamil affects 162 targets in human airway granulosa fibroblasts, among which, the most concerned and core target proteins are TGF-β1, VEGFA and IL-6; mainly involved in biological processes such as apoptosis, angiogenesis, energy metabolism and inflammation, and AGE-RAGE, JAK-STAT, PI3K-AKT, HIF as well as IL-17 signaling pathways. Molecular docking results showed that verapamil can bind to key targets. The apoptosis rate of human airway granulomatous fibroblasts treated with verapamil was higher than that of the control group, and the difference was statistically significant (P < 0.05). PCR showed that the relative expression of TGF-β1, VEGFA, IL-6 and other mRNAs in human airway granulomatous fibroblasts was significantly higher than that in human normal airway fibroblasts (P < 0.05), whereas the relative expression of TGF-β1 mRNA was down-regulated (P < 0.05) and the mRNA expression of VEGFA, IL-6 did not change significantly (P > 0.05) in human airway granulosa fibroblasts after treatment with verapamil. Conclusions: Increasing the antibiotic concentration and combining multiple antibiotics to soak the tissue can effectively kill the tissue pathogens. Verapamil can inhibit the proliferation of airway granulomatous fibroblasts through multiple targets and pathways, and it may be a method to prevent and treat benign airway stenosis.

The impact of Verapamil for radial access in diagnostic cerebrovascular angiograms: A retrospective case-control study.

Different combinations of medications are utilized during wrist access for radial artery (RA) or ulnar artery (UA) catheterization in neuroendovascular procedures to preclude vasospasm. These "cocktails" commonly include the calcium channel blocker Verapamil, without established benefit. We analyze outcomes in patients with and without Verapamil in their "cocktail" by using a case-control cohort of our single-center experience. A prospective log of consecutive patients who underwent diagnostic cerebral angiograms using RA/UA access was retrospectively reviewed, and patients were grouped into Verapamil and non-Verapamil cohorts. The primary outcomes assessed were the presence of forearm skin rashes (hives) and RA/UA spasms. Our initial management included Verapamil (5 mg) in the cocktail, but Verapamil was removed after we noticed the development of hives in multiple patients immediately following its injection. A total of 221 patients underwent 241 RA/UA diagnostic cerebral angiograms and were included in our analysis. One hundred and forty-nine patients (61.8%) underwent catheterization with Verapamil and 92 (38.2%) were catheterized without it. Four of the 149 patients in the Verapamil group (2.7%) developed hives during the procedure and were treated with Benadryl (25 mg). Of the 92 patients who did not receive Verapamil, there were zero (0%) cases of hives and one (1.1%) case of vasospasm. Verapamil in the "cocktail" for wrist access diagnostic cerebral angiograms was associated with periprocedural hives, but not associated with a significant reduction in spasm compared to the non-Verapamil group. Our findings suggest that the administration of prophylactic Verapamil for these procedures may not be necessary.

An Update on Impacts of Epigallocatechin Gallate Co-administration in Modulating Pharmacokinetics of Statins, calcium channel blockers and beta-blockers.

Brewed green tea, green tea extract (GTE), and its primary active compound, epigallocatechin gallate (EGCG) may interact with drugs and alter the drug's therapeutic effectiveness ultimately leading to therapeutic failure or drug overdose. Several isolated reports have claimed that EGCG is the main active ingredient that causes these effects. Several isolated reports have claimed that EGCG is the main active ingredient that causes these effects. While a few studies aimed to uncover evidence of EGCG-drug interactions, no study has thoroughly and collectively reviewed them. EGCG is a potential cardio-protective agent used by many patients with cardiovascular diseases as a complementary medicine alongside conventional modern medications, either with or without the knowledge of their physicians. Therefore, this review focuses on the impact of concurrent EGCG supplementation on pharmacokinetics and pharmacodynamics of several commonly used cardiovascular drugs (statins, beta-blockers, and calcium channel blockers). Pubmed index was searched for keywords related to this review, without year limit and the results analysed for interactions of cardiovascular drugs with EGCG. This review concludes that EGCG increases systemic circulation of several statins (simvastatin, fluvastatin, rosuvastatin,) and calcium channel blockers (verapamil), but decreases the bioavailability of beta-blockers (nadolol, atenolol, bisoprolol). Further studies on its clinical significance in affecting drug efficacy are required.

Effectiveness of Calcium Channel Blockers and Nitrates in Inhibition of Spasm of Radial Artery during Coronary Angiography

Background: The most common issue with transradial cardiac catheterization is radial artery vasospasm. The patient experiences pain and discomfort as a result, the procedure is prolonged, and the interventionist may even be unable to continue. Aim: The aim of the study is to determine the effectiveness of Verapamil, a calcium channel blocker and nitrate, when used together to prevent radial artery spasm during coronary angiographies. Methods: This case control study was held in the Cardiology department of Qazi Hussain Ahmed Medical Complex, Nowshera and Peoples University of Medical and Health Sciences for Women PUMHSW (SBA) Nawabshah for six-months duration from July 2021 to December 2021 including 120 cardiac patients undergoing coronary angiography. The patients were selected by non-probability sampling technique. Patients who were enrolled in the study provided written informed consent. Two groups of patients—control (60) and experimental—were formed (60). Heparin/nitrate was administered to one group and labelled as a control group, while heparin/nitrates/verapamil (a calcium channel blocker) was administered to the other group considered as an experimental group. During the angiography procedure, the radial spasm, discomfort, and catheter resistance were assessed in both groups. A predesigned questionnaire was used to collect all other demographic data and patient’s history. SPSS version 23.0 was used to collect and analyse the data. Results: It was found that 68.3% of cardiac patients were over 50 years old, 41.7% of patients were female, and 58.3% of patients were male. Verapamil, a calcium channel blocker, and nitrate did not significantly affect radial spasm, according to this study with a p value of 0.762. According to the study, there was no obvious difference noted in radial spasm, outcome, discomfort, catheter resistance, or procedure time when cases and controls were compared for various variables. However, the test group have a 100% success rate of the procedure compared to the control group's 95%. Conclusion: Verapamil, a calcium channel blocker when combined with nitrate did not significantly reduce radial spasm during coronary angiography. The theory that calcium channel blockers could prevent radial artery spasm during angiography was nullified. It is best to avoid the financial burden that comes with using calcium channel blockers and nitrate during coronary angiography. Combining nitrate and calcium channel blocker (Verapamil) has no additional advantages. Keywords: Angiography, catheterization, calcium channel blocker, radial spasm, nitrate, and verapamil are some of the related terms.

Chemerin-9 in paraventricular nucleus increases sympathetic outflow and blood pressure via glutamate receptor-mediated ROS generation

Chemerin is an adipokine involved in regulating energy homeostasis and reproductive function. Excessive sympathetic activity contributes to hypertension, chronic heart failure and chronic renal disease. Hypothalamic paraventricular nucleus (PVN) is crucial in regulating sympathetic activity and blood pressure. The present study is designed to investigate the roles of chemerin in the PVN in regulating sympathetic activity and blood pressure and underlying mechanisms. Microinjections were performed in the bilateral PVN in male adult rats under anesthesia. Renal sympathetic nerve activity (RSNA) and mean arterial pressure (MAP) were continuously recorded. The PVN microinjection of chemerin-9, an active fragment of chemerin, increased RSNA and MAP, which were abolished by chemokine-like receptor 1 (CMKLR1) antagonist α-NETA, a superoxide scavenger tempol, antioxidant N-acetylcysteine (NAC), NADPH oxidase inhibitor diphenyleneiodonium chloride (DPI) and apocynin. Immunofluorescence analyses showed that N-methyl-D-aspartate (NMDA) receptors existed in most of cells of the PVN, and some of them co-existed with chemerin. The effects of chemerin-9 on RSNA and MAP were prevented by glutamate-binding site antagonist L-phenylalanine, NMDA receptor antagonist MK-801, and calcium channel blocker verapamil or nifedipine, but only attenuated by non-NMDA receptor antagonist CNQX. Moreover, chemerin-9 increased NADPH oxidase activity and superoxide production, which were prevented by α-NETA, MK-801, or verapamil. These results indicate that chemerin-9 in the PVN increases sympathetic activity and blood pressure via CMKLR1-dependent calcium influx, and glutamate receptor-mediated NADPH oxidase activation and subsequent superoxide production.

Rapid antidepressant-like effects of muscarinic receptor antagonists require BDNF-dependent signaling in the ventrolateral periaqueductal gray.

Clinical reports reveal that scopolamine, an acetylcholine muscarinic receptor antagonist, exerts rapid antidepressant effects in depressed patients, but the mechanisms underlying the therapeutic effects have not been fully identified. The present study examines the cellular mechanisms by which scopolamine produces antidepressant-like effects through its action in the ventrolateral midbrain periaqueductal gray (vlPAG). We used a well-established mouse model of depression induced by chronic restraint stress (CRS) exposure for 14days. Behaviors were tested using the forced swim test (FST), tail suspension test (TST), female urine sniffing test (FUST), novelty-suppressed feeding test (NSFT), and locomotor activity (LMA). Synaptic transmission in the vlPAG was measured by whole-cell patch-clamp recordings. IntravlPAG microinjection was used to pharmacologically verify the signaling cascades of scopolamine in the vlPAG. The results demonstrated that intraperitoneal injection of scopolamine produced antidepressant-like effects in a dose-dependent manner without affecting locomotor activity. CRS elicited depression-like behaviors, whereas intraperitoneal injection of scopolamine alleviated CRS-induced depression-like behaviors. CRS diminished glutamatergic transmission in the vlPAG, while scopolamine reversed the above effects. Moreover, intravlPAG microinjection of the L-type voltage-dependent calcium channel (VDCC) blocker verapamil, tropomyosin-related kinase B (TrkB) receptor antagonist ANA-12, mammalian target of rapamycin complex 1 (mTORC1) inhibitor rapamycin, and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPA) antagonist CNQX prevented scopolamine-induced antidepressant-like effects. Scopolamine ameliorated CRS-elicited depression-like behavior required activation of VDCC, resulting in activity-dependent release of brain-derived neurotrophic factor (BDNF), engaging the TrkB receptor and downstream mTORC1 signalingin the vlPAG.

Physiological Effects of Condensed Tannins from Black Currant (Ribes nigrum L.) on Isolated Rat Duodenal Contraction

Condensed tannins (CTs) extracted from various plants have been shown to possess antioxidant, antidiabetic, anthelmintic, anti-palatable and anti-diarrhea activity. Black currant (Ribes nigrum L.), a native plant of northern Europe and Asia, is rich in phenolic compounds, including CTs. Among the biological activities of CTs, their astringent property is likely to affect gastrointestinal motility. This study aimed to investigate the physiological effect of CTs from black currant (R. nigrum L.) leaves on isolated rat duodenal contraction. Duodenal segments were fixed in organ baths containing carbogen aerated Krebs solution at the resting tension of 0.7 - 0.8 g. The frequency, amplitude, and tone of duodenal contraction were recorded. Either CTs or acetylcholine (ACh) were cumulatively added into the bath at the concentration of between 0.001 - 10 µg/mL and 10–8 - 10–4 M, respectively. The mechanisms of CTs and ACh actions were studied using muscarinic receptor antagonist (atropine, 1.55×10–5 M) and calcium channel blocker (verapamil, 10–6 M). It is found that CTs at the concentration between 0.001 - 10 µg/mL had no direct effect on duodenal frequency, amplitude, and tone of contraction, whereas ACh showed a significant increase in tonic contraction, was suppressed by atropine. Interestingly, in the presence of atropine and verapamil, CTs showed a further significant decrease in the amplitude of duodenal contraction compared to the effect of these 2 blockers alone. It is concluded that CTs would synergize the activity of the muscarinic receptor antagonist and the calcium channel blocker at duodenal enteric neurons or smooth muscle membrane. However, the use of CTs from black currant (R. nigrum L.) leaves to treat gastro-intestinal disorders while having muscarinic receptor antagonist or calcium channel blocker need cautions.
 HIGHLIGHTS
 
 Black currant (Ribes nigrum L.), a native plant of northern Europe and Asia, is rich in phenolic compounds including condensed tannins (CTs) and their astringent property is likely to affect gastrointestinal motility
 CTs isolated from leaves of black currant (R. nigrum L.) at the physiological doses (0.001 - 10.0 µg/mL) have no direct effect on isolated rat duodenal contraction
 CTs may possess the synergistic or additive effect with either atropine, a nonselective muscarinic receptor, or verapamil, a calcium channel blocker on duodenal amplitude of contraction
 
 GRAPHICAL ABSTRACT

Antiarrhythmic calcium channel blocker verapamil inhibits trek currents in sympathetic neurons.

Background and Purpose: Verapamil, a drug widely used in certain cardiac pathologies, exert its therapeutic effect mainly through the blockade of cardiac L-type calcium channels. However, we also know that both voltage-dependent and certain potassium channels are blocked by verapamil. Because sympathetic neurons of the superior cervical ganglion (SCG) are known to express a good variety of potassium currents, and to finely tune cardiac activity, we speculated that the effect of verapamil on these SCG potassium channels could explain part of the therapeutic action of this drug. To address this question, we decided to study, the effects of verapamil on three different potassium currents observed in SCG neurons: delayed rectifier, A-type and TREK (a subfamily of K2P channels) currents. We also investigated the effect of verapamil on the electrical behavior of sympathetic SCG neurons. Experimental Approach: We employed the Patch-Clamp technique to mouse SCG neurons in culture. Key Results: We found that verapamil depolarizes of the resting membrane potential of SCG neurons. Moreover, we demonstrated that this drug also inhibits A-type potassium currents. Finally, and most importantly, we revealed that the current driven through TREK channels is also inhibited in the presence of verapamil. Conclusion and Implications: We have shown that verapamil causes a clear alteration of excitability in sympathetic nerve cells. This fact undoubtedly leads to an alteration of the sympathetic-parasympathetic balance which may affect cardiac function. Therefore, we propose that these possible peripheral alterations in the autonomic system should be taken into consideration in the prescription of this drug.

P2.05: Influence of Adding Calcium Channel Blocker Verapamil During Perfusion for Functioning Transplanted Kidney Within 36 Months After Transplantation (Mid Term Results)

P2.05: Influence of Adding Calcium Channel Blocker Verapamil During Perfusion for Functioning Transplanted Kidney Within 36 Months After Transplantation (Mid Term Results)

Acute and Delayed Cerebrovascular Injury From Gunshot to the Head in a 12-Year-Old Child During the COVID-19 Pandemic

Acute and Delayed Cerebrovascular Injury From Gunshot to the Head in a 12-Year-Old Child During the COVID-19 Pandemic

Pharmacological Management of Atrial Fibrillation: A Century of Expert Opinions in Cecil Textbook of Medicine.

Advances in drug therapy for atrial fibrillation (AF) have had a significant impact on the quality of life of a substantial majority of affected persons, which has contributed to a remarkable decrease in the frequency and severity of thromboembolic complications, hospitalizations, and mortality. What are the milestones of the changes in the expert approach to the pharmacological management of AF in the past century? To determine the changes in the experts' approach to the management of AF, as presented in a widely used textbook in the United States. The chapters presenting the management of AF in the 26 editions of Cecil Textbook of Medicine published from 1927 through 2020. AF was consistently described in Cecil Textbook of Medicine as the most common sustained arrhythmia in adults. The authors emphasized its thromboembolic complications and potential for hemodynamic deterioration. Rate control with digitalis and rhythm control with quinidine were the standard in 1927. The pharmacological advances have focused on atrioventricular nodal blocking for rate control, conversion to and maintenance of sinus rhythm, and preventive anticoagulation. The first new class of drugs for rate control was beta-adrenergic receptor blockers, starting with propranolol which was introduced in 1979, followed by the calcium channel blocker verapamil in 1988. Rhythm control with amiodarone, a potassium channel blocker, has been recommended since 2004, and the sodium channel blockers propafenone and flecainide became part of standard therapy in 2008. Anticoagulation with warfarin was recommended starting in 2000, followed by the introduction of direct thrombin inhibitor in 2012 and factor Xa inhibitors in 2016. The pharmacological management of AF was unchanged for more than 50 years (1927-1979), a period during which the devastating effects of thromboembolic complications were not addressed. The major therapeutic advance is represented by preventive anticoagulation with the newer, safer, and more user-friendly direct thrombin and factor Xa inhibitors.

The interactive effects of verapamil and CB1 cannabinoid receptor antagonist/inverse agonist, AM251 on passive avoidance learning and memory in rat.

There are reports regarding the effects of intracellular Ca2+ and synthesis and release of endocannabinoids. The secretion of endocannabinoids depends on the L-type calcium channel. The present study evaluated the involvement of the cannabinoid CB1 receptors in the effect of L-type calcium channel blocker verapamil on passive avoidance learning (PAL) in adult male rats. In this study, we examined the effects of an acute administration of the cannabinoid CB1 receptors antagonist/inverse agonist AM251 following a chronic administration of the Ca2+ channel blocker verapamil on PAL. Male Wistar rats were administered verapamil (10, 25 and 50 mg/kg) or saline intraperitoneally (i.p) daily for 13 days (n = 10/group). After this treatment period, a learning test (acquisition) was performed, and a retrieval test was performed the following day. The results indicated that chronic systemic administration of verapamil (in a dose-dependent manner) impaired memory acquisition and retrieval. Pre-training acute administration of a selective CB1 antagonist/inverse agonist, AM251 (5 mg/kg, i.p.) did not change memory acquisition and retrieval. Co-administration of the verapamil and AM251 significantly reversed verapamil-induced amnesia, suggesting a functional interaction between AM251 and verapamil. The results indicated the interactive effects of cannabinoid CB1 receptors and L-type calcium channel in passive avoidance learning and AM251 can counter the effects of verapamil on memory.

Abstract 13052: Antiarrhythmic Effect of Artemisinin in Canine Experimental Model of Brugada Syndrome

Introduction: Brugada syndrome is an inherited arrhythmia syndrome which presents sudden cardiac death (SCD) without structural heart diseases. One of the mechanisms of SCD has been suggested that uneven dispersion of Ito channel between epicardium and endocardium induces ventricular arrhythmia. Hypothesis: Artemisinin is used as antimalarial drug widely. Its antiarrhythmic effect which included suppression of Ito channel was reported previously. We investigated the effect of Artemisinin for suppression of Brugada syndrome in canine experimental model Methods: Transmural pseudo-ECG and epicardial/endocardial action potentials were recorded from coronary-perfused canine right ventricular wedge preparation (N=7). To mimic the Brugada syndrome model, acetylcholine (3 μM), calcium channel blocker verapamil (1 μM), Ito agonist NS5806 (7-10 μM) were used and waited until ventricular arrhythmia induction. Then, Artemisinin 100-150 μM was perfused to ameliorate the ventricular arrhythmia. Action potential duration, J wave area, notch index and T wave dispersion were measured. Results: In 5 sample models, ventricular arrhythmia was induced. The Artemisinin suppressed ventricular arrhythmia (n=5) and recovering the action potential dome of RV epicardium after provocation of ventricular arrhythmia in all preparations (n=7). J wave area and epicardial notch index were also decreased after Artemisinin perfusion. Action potential duration prolonged as the ventricular arrhythmia provocation and recovered after Artemisinin perfusion. Conclusions: Our findings suggest that Artemisinin alleviate the Brugada syndrome in the wedge preparation model by inhibition of Ito channel and it suppressed the development of phase 2 reentry and ventricular tachycardia/ventricular fibrillation.