The Novel Gabapentinoid Mirogabalin Prevents Upregulation of α2δ-1 Subunit of Voltage-Gated Calcium Channels in Spinal Dorsal Horn in a Rat Model of Spinal Nerve Ligation.

Gabapentinoids are specific ligands for the α2δ-1 subunit of voltage-gated calcium channels. This class of drugs, including gabapentin and pregabalin, exert various pharmacological effects and are widely used for the treatment of epilepsy, anxiety, and chronic pain. The mechanism of action of gabapentinoids involves both direct modulation of calcium channel kinetics and inhibition of channel trafficking and expression, which contribute to the above pharmacological effects. In the present study, we investigated the effects of mirogabalin, a novel potent gabapentinoid, on expression levels of the α2δ-1 subunit in the spinal dorsal horn in a rat model of spinal nerve ligation (SNL) as an experimental animal model for peripheral neuropathic pain. The neuropathic pain state was induced by SNL in male Sprague - Dawley rats. After the development of mechanical hypersensitivity, the animals received 10 mg/kg mirogabalin or vehicle orally for 5 consecutive days and were subjected to immunohistochemical analysis of α2δ-1 subunit expression in the spinal cord. In the SNL model rats, expression of the α2δ-1 subunit significantly increased in the spinal dorsal horn at the ipsilateral side of nerve injury, while mirogabalin inhibited this increase. In conclusion, the α2δ-1 subunit was upregulated in the spinal dorsal horn of SNL model rats, and repeated administration of mirogabalin inhibited this upregulation. The inhibitory effect of mirogabalin on upregulation of the α2δ-1 subunit after nerve injury is considered to contribute to its analgesic effects in peripheral neuropathic pain.

Association between CACNA1C gene rs100737 polymorphism and glutamatergic neurometabolites in bipolar disorder.

Abnormalities in Ca2+ homeostasis in Bipolar Disorders (BD) have been associated with impairments in glutamatergic receptors and voltage-gated calcium channels. Increased anterior cingulate cortex (ACC) glutamatergic neurometabolites have been consistently disclosed in BD by proton magnetic resonance spectroscopy (1H-MRS). A single nucleotide polymorphism (SNP) in the CACNA1C gene (rs1006737), which encodes the alpha 1-C subunit of the L-type calcium channel, has been associated with BD and is reported to modulate intra-cellular Ca2+. Thus, this study aimed to explore the association of the CACNA1C genotype with ACC glutamatergic metabolites measured by 1H-MRS in both BD and HC subjects. A total of 194 subjects (121 euthymic BD type I patients and 73 healthy controls (HC) were genotyped for CACNA1C rs1006737, underwent a 3-Tesla 1H-MRS imaging examination and ACC glutamatergic metabolite were assessed. We found overall increased glutamatergic metabolites in AA carriers in BD. Specifically, higher Glx/Cr was observed in subjects with the AA genotype compared to both AG and GG in the overall sample (BD + HC). Also, female individuals in the BD group with AA genotype were found to have higher Glx/Cr compared to those with other genotypes. CACNA1C AA carriers in use of anticonvulsant medication had higher estimated Glutamine (Glx-Glu) than the other genotypes. Thus, this study suggest an association between calcium channel genetics and increased glutamatergic metabolites in BD, possibly playing a synergic role in intracellular Ca2+ overload and excitotoxicity.

Ameliorative Impact of Liraglutide on Chronic Intermittent Hypoxia-Induced Atrial Remodeling.

Atrial fibrillation (AF) is the most frequent form of clinical cardiac arrhythmias. Previous evidence proved that atrial anatomical remodeling (AAR) and atrial electrical remodeling (AER) are crucial for the progression and maintenance of AF. This study is aimed at investigating the impact of the glucagon-like peptide-1 (GLP-1) receptor agonist, Liraglutide (Lir), on atrial remodeling (AR) mouse model induced by chronic intermittent hypoxia (CIH). C57BL/6 mice were categorized randomly into the control, Lir, CIH, and CIH+Lir groups. CIH was performed in CIH and CIH+Lir groups for 12 weeks. Lir (0.3 mg/kg/day, s.c) was administered to the Lir and CIH+Lir groups for four weeks, beginning from the ninth week of CIH. Meanwhile, echocardiography and right atrial endocardial electrophysiology via jugular vein, as well as induction rate and duration of AF, were evaluated. Masson and Sirius red staining assays were utilized to assess the extent of fibrosis in the atrial tissue of the mice. Immunohistochemical staining, RT-qPCR, and Western blotting were performed to evaluate the marker levels of AAR and AER and the expression of genes and proteins of the miR-21/PTEN/PI3K/AKT signaling pathway, respectively. ELISA was also performed to evaluate the changes of serum inflammatory factor levels. The CIH group exhibited significant AR, increased atrial fibrosis, and a higher incidence rate of AF compared to the control group. Lir could significantly downregulate the protein expression level in the PI3K/p-AKT pathway and upregulated that of phosphatase and tensin homolog deleted on chromosome ten (PTEN). Moreover, Lir downregulated the expression of miR-21. However, the protein expressions of CACNA1C and KCNA5 in atrial tissue were not changed significantly. In addition, Lir significantly attenuated the levels of markers of inflammation (TNF-α and IL-6) in the serum. In the mouse model of CIH, Lir treatment could ameliorate AR by the miR-21/PTEN/PI3K/AKT signaling pathway and modulation of inflammatory responses.

Influence of pregabalin maintenance on cannabis effects and related behaviors in daily cannabis users.

No medications are approved for cannabis use disorder (CUD), though a small clinical trial demonstrated that the voltage-dependent calcium channel (VDCC) ligand gabapentin reduced cannabis use in treatment seekers. VDCCs are modulated by cannabinoid (CB) ligands, and there are shared effects between CB agonists and VDCC ligands. This overlapping neuropharmacology and the initial clinical results supported the evaluation of pregabalin, a "next-generation" VDCC ligand, as a CUD medication. Two separate placebo-controlled, double-blind, counterbalanced, within-subjects human laboratory studies tested placebo and 300 (N = 2 females, 11 males; Experiment [EXP] 1) or 450 (N = 3 females, 11 males; EXP 2) mg/day pregabalin in cannabis users who were not seeking treatment or trying to reduce/quit their cannabis use. The protocol consisted of two outpatient maintenance phases (11 days in EXP 1 and 15 days in EXP 2) that concluded with four experimental sessions within each phase. During experimental sessions, maintenance continued, and participants completed two 2-day blocks of sampling and self-administration sessions to determine the reinforcing effects of smoked cannabis (0% and 5.9% delta9-tetrahydrocannabinol [THC]), as well as subjective, attentional bias, performance, and physiological responses. In addition, naturalistic cannabis use, side effects, sleep quality, craving, and other self-reported substance use were measured during pregabalin maintenance. Cannabis was self-administered and produced prototypical effects, but pregabalin generally did not impact the effects of cannabis or alter naturalistic use. These human laboratory results in cannabis users not trying to reduce/quit their use do not support the efficacy of pregabalin as a stand-alone pharmacotherapy for CUD. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Single-pill combination of cilnidipine, an l-/n-type calcium channel blocker, and valsartan reduces the day-by-day variability of morning home systolic blood pressure in patients with treated hypertension: A sub-analysis of the HOPE-combi survey.

We examined the effects of a fixed-dose single-pill combination of cilnidipine (10 mg), an L-/N-type calcium channel blocker, and valsartan (80 mg) (SPC of Cil/Val) on the day-by-day variability of morning home systolic blood pressure (MHSBP) in 616 patients with treated hypertension for 12 months as a sub-analysis of the HOPE-Combi survey, multicentral, post-marketing, and prospective observational survey. The SPC of Cil/Val was administrated once a day in the morning. The SPC of Cil/Val decreased the standard deviation (SD, from 6.3 ± 4.8 to 5.1 ± 3.8 mmHg, p < .01), coefficient of variation (from 4.3 ± 3.2 to 3.8 ± 2.9%, p < .05), average real variability (ARV, from 7.9 ± 6.6 to 6.3 ± 5.1 mmHg, p < .01), and the difference between maximum and minimum (MMD, from 11.9 ± 9.2 to 9.7 ± 7.2 mmHg, p < .01) of MHSBP. The variability of MHSBP increased with age; however, this was not increased in patients ≥70 years at the baseline. In elderly patients (≥70 years, N = 283), the SPC of Cil/Val decreased the SD (from 6.9 ± 5.6 to 5.6 ± 4.4 mmHg, p < .01), ARV (from 8.6 ± 7.7 to 6.9 ± 5.7 mmHg, p < .05), and MMD (from 13.2 ± 10.7 to 10.7 ± 8.3 mmHg, p < .01) of MHSBP at 12 months; the reduction in these MHSBP variability parameters was comparable to that in adults <70 years. These results suggest that the SPC of Cil/Val is effective in reducing day-by-day variability of MHSBP in elderly patients.

Single-pill combination of cilnidipine, an L-/N-type calcium channel blocker, and valsartan effectively reduces home pulse pressure in patients with uncontrolled hypertension and sympathetic hyperactivity: The HOPE-Combi survey.

The home blood pressure (BP) control by a single-pill combination of cilnidipine (an L-/N-type calcium channel blocker; CCB) and valsartan (HOPE-Combi) survey is a multicenter, post-marketing, prospective observational study of a single-pill combination of cilnidipine 10 mg and valsartan 80 mg (SPC of Cil/Val) in patients with uncontrolled hypertension. We examined the effects of the SPC of Cil/Val on morning home systolic BP (MHSBP) and morning home pulse pressure (MHPP) of 1036 patients with hypertension over 12 months. MHSBP decreased by 14.0 mm Hg (P < .01), and MHPP decreased by 6.6 mm Hg (P < .01). Moreover, morning home pulse rate (MHPR) decreased by 2.1 bpm (P < .01). A more progressive and greater decrease in MHSBP (-17.2 vs -10.3 mm Hg, P < .01) and MHPP (-7.6 vs -4.9 mm Hg, P < .01) was observed in patients with higher MHPR (≥70 bpm) than in those with lower MHPR (<70 bpm) over the treatment period. In particular, in patients with a wide MHPP (≥70 mm Hg), the difference in the MHPP reduction was greater in patients with higher MHPR than in those with lower MHPR (-17.9 vs -13.6 mm Hg, P < .01). These results suggested that the SPC of Cil/Val, which possesses the unique sympatholytic characteristics of an L-/N-type CCB, was particularly effective in patients with uncontrolled hypertension and sympathetic hyperactivity.

Randomised clinical trial: otilonium bromide improves frequency of abdominal pain, severity of distention and time to relapse in patients with irritable bowel syndrome.

BACKGROUND: Otilonium bromide (OB) is a spasmolytic agent that blocks L-Type Calcium channels in human colonic smooth muscle. AIM: To study the efficacy of OB in symptom control in irritable bowel syndrome (IBS). METHODS: A total of 356 patients (46.16±19years, 71% female) with IBS participated in a double-blind, randomised, parallel placebo-controlled phase IV study. OB (40mg t.d.s.) or placebo was administered for 15weeks, and follow-up was extended 10 additional weeks. RESULTS: Otilonium bromide (n=179) and placebo (n=177) groups had comparable demographics, symptom severity and IBS subtype. Both OB and placebo reduced abdominal pain and IBS symptoms. The effect of OB was significantly greater than placebo in the reduction of weekly frequency of episodes of abdominal pain at the end of treatment period (primary endpoint, -0.90±0.88 vs. -0.65±0.91, P=0.03), reduction of abdominal bloating (-1.2±1.2 vs. -0.9±1.1, P=0.02) and global efficacy by patient assessment (1.3±1.1 vs. 1.0±1.1, P=0.047). Intensity of abdominal pain, proportion of patient responders, safety and quality of life scores were similarly affected by OB and placebo. During follow-up, the therapeutic effect of OB remained greater than placebo in terms of withdrawal rate due to symptom relapse (10% vs. 27%, P=0.009), global efficacy of treatment and relapse-free probability (P=0.038). CONCLUSIONS: This placebo-controlled double-blind study shows that otilonium bromide is safe, well tolerated and superior to placebo in reducing the frequency of abdominal pain, severity of abdominal bloating and protecting from symptom relapse in IBS. These results further confirm that patients with IBS can improve during and following treatment with otilonium bromide.

Inhibitory effects of T/L-type calcium channel blockers on tubulointerstitial fibrosis in obstructed kidneys in rats.

OBJECTIVES: To examine the effect of L- and T/L-type calcium channel blockers on interstitial fibrosis in chronic unilateral ureteral obstruction (UUO). Tubulointerstitial fibrosis is a common outcome of several progressive renal diseases. Calcium channel blockers are widely used for the treatment of hypertension with renal diseases; however, the direct effect of calcium channel blockers on renal diseases independent of lowering blood pressure has not been fully elucidated. METHODS: Sprague-Dawley rats were divided into 3 treatment groups: (1) vehicle control; (2) nifedipine, an L-type calcium channel blockers; and (3) efonidipine, a T/L-type calcium channel blockers. Treatment was initiated 1 day before and continued until 6 days after creation of the UUO. RESULTS: Tubulointerstitial fibrosis in the obstructed kidney was significantly increased compared with that in the contralateral unobstructed kidney. Furthermore, the increased fibrosis was accompanied by increased fibrogenic signaling expressed by transforming growth factor ß1 and connective tissue growth factor mRNA levels, increased oxidative stress expressed by p22phox, p47phox and gp91phox mRNA level. Moreover, treatment with a nonhypotensive dose of efonidipine but not nifedipine in the obstructed kidney significantly suppressed the fibrogenic signaling and the oxidative stress, resulting in reduced tubulointerstitial fibrosis. The plasma aldosterone level in efonidipine-treated animals was increased compared with vehicle-treated animals, although not significantly. The increased plasma aldosterone level did not increase sgk-1 mRNA level in efonidipine but not in nifedipine treated animals. CONCLUSIONS: Treatment with efonidipine improved tubulointerstitial fibrosis more effectively than treatment with nifedipine in UUO. The antifibrogenic effect by efonidipine was obtained through suppression of fibrogenic signaling.

Excitation-contraction coupling from the 1950s into the new millennium.

1. Excitation-contraction coupling is broadly defined as the process linking the action potential to contraction in striated muscle or, more narrowly, as the process coupling surface membrane depolarization to Ca(2+) release from the sarcoplasmic reticulum. 2. We now know that excitation-contraction coupling depends on a macromolecular protein complex or 'calcium release unit'. The complex extends the extracellular space within the transverse tubule invaginations of the surface membrane, across the transverse tubule membrane into the cytoplasm and then across the sarcoplasmic reticulum membrane and into the lumen of the sarcoplasmic reticulum. 3. The central element of the macromolecular complex is the ryanodine receptor calcium release channel in the sarcoplasmic reticulum membrane. The ryanodine receptor has recruited a surface membrane L-type calcium channel as a 'voltage sensor' to detect the action potential and the calcium-binding protein calsequestrin to detect in the environment within the sarcoplasmic reticulum. Consequently, the calcium release channel is able to respond to surface depolarization in a manner that depends on the Ca(2+) load within the calcium store. 4. The molecular components of the 'calcium release unit' are the same in skeletal and cardiac muscle. However, the mechanism of excitation-contraction coupling is different. The signal from the voltage sensor to ryanodine receptor is chemical in the heart, depending on an influx of external Ca(2+) through the surface calcium channel. In contrast, conformational coupling links the voltage sensor and the ryanodine receptor in skeletal muscle. 5. Our current understanding of this amazingly efficient molecular signal transduction machine has evolved over the past 50 years. None of the proteins had been identified in the 1950s; indeed, there was debate about whether the molecules involved were, in fact, protein. Nevertheless, a multitude of questions about the molecular interactions and structures of the proteins and their interaction sites remain to be answered and provide a challenge for the next 50 years.

A comparison between calcium channel blocking drugs with different potencies for T- and L-type channels in preventing atrial electrical remodeling.

Calcium overload plays a key role in the development of atrial electrical remodeling. The effect of an L-type Ca channel blocker in preventing this remodeling has been reported to be short lasting, partly due to down-regulation of this channel and persisting Ca entry through the T-type Ca channel. To prove if efonidipine, a dual L- and T-type Ca channel blocker exerts a greater effect than an L-type Ca channel blocker verapamil, 21 dogs underwent rapid atrial pacing at 400 bpm for 14 days, pretreatment with efonidipine in 7 (E), verapamil in 7 (V), and none in 7 (C). We measured the atrial effective refractory period (ERP) serially during 14 days of rapid pacing. In response to rapid pacing, ERP decreased progressively in C. In contrast, in E and V, ERP remained greater than ERP in C (P < 0.01) on days 2 through 7. However, on the 14th day, ERP in V decreased to the level seen in C, whereas ERP in E remained significantly longer than ERPs in C or V (P < 0.01). The blockade L-type Ca channel alone is not sufficient, but the addition of a T-type Ca channel blockade shows a more sustained effect to prevent atrial electrical remodeling.

Is calcium sensitization the best strategy to improve myocardial contractility in acute heart failure?

The finely-tuned increases and decreases in the intracellular calcium levels in myocytes ultimately regulate the contraction and relaxation of the heart. Therapeutic agents can improve or interfere with this delicate balance. Calcium sensitizers enhance cardiac contraction by improving the use of calcium that is available, rather than by inundating the cell with excessive calcium, as is the case with traditional inotropes. With the sensitizing mechanism, the energy cost of contraction is maintained at a near-normal level, and the threat of arrhythmias and sudden death is low. Levosimendan is the first calcium sensitizer to become available for the treatment of patients with acute heart failure. In recent clinical studies, levosimendan increased cardiac output and stroke volume without significantly increasing oxygen demand. By its additional action as a vasodilator (via potassium channel opening), levosimendan also corrects the hemodynamic decompensation, thus lowering the pulmonary capillary wedge pressure and systemic vascular resistance. Furthermore, levosimendan increases the coronary circulation thus leading to an improved function of the stunned myocardium and lessened ischemia. Taken together, levosimendan's primary calcium-sensitizing action, along with its complementary vasodilator properties, make this new drug a highly promising agent for the treatment of patients with acute heart failure.

Considerations on the efficacy and safety of levosimendan in ischemic heart failure.

Levosimendan is a new vasodilator agent with properties which improve cardiac contractility by calcium sensitization. Its dose-related efficacy and prolonged action have been documented in several major studies both against placebo and dobutamine. Out of 997 patients, 837 (84%) had acute or stable heart failure due to coronary heart disease. Therefore, it would be most interesting to analyze the efficacy and safety of levosimendan in heart failure due to ischemic heart disease. The dose-finding study included 98 patients who were given intravenous levosimendan at different doses and 20 patients treated with dobutamine. All patients had heart failure due to coronary heart disease. The other major trial included 500 acute myocardial infarction patients with heart failure and was placebo-controlled. In other levosimendan vs placebo or dobutamine comparative trials 50-60% of patients had ischemic heart disease and severe heart failure. Levosimendan significantly improves the cardiac index by 30-39% at bolus doses of 6-24 micrograms/kg/min followed by infusion doses of 0.05-0.2 microgram/kg/min and reduces the wedge pressure by 20-25% to optimal levels (from 15-20 mmHg). There is a lesser blood pressure reduction and some heart rate increase. However in patients with an acute myocardial infarction the rate of ischemia or hypotension were similar in levosimendan- and placebo-treated patients and in the dobutamine controlled trials no major adverse effects were seen or they were more frequent in dobutamine patients. There is no increase in mortality either compared to placebo or to dobutamine. Rather, the opposite seems to be true. No increase in arrhythmias is seen. The hemodynamic effects of levosimendan are dose-dependent and the current recommended doses are safe. No increase in mortality or any life-threatening arrhythmias have been observed.

Levosimendan in patients with low-output heart failure: lessons from the LIDO trial.

The novel calcium sensitizer levosimendan improves myocardial contractility without causing an increase in intracellular calcium and cyclic adenosine monophosphate concentrations. It also has a vasodilator action due to an opening of the adenosine triphosphate-sensitive potassium channels. In a double-blind clinical trial levosimendan was compared with dobutamine in 203 patients with severe low-output congestive heart failure. A 24-hour infusion of these inotropic drugs was administered to increase the cardiac output by at least 30% together with a decrease in the pulmonary capillary wedge pressure by > or = 25%. The pre-defined hemodynamic improvement was achieved in 28% of patients receiving levosimendan compared to only 15% with dobutamine (p = 0.022). Levosimendan also reduced the 1- and 6-month mortality more than dobutamine (7.8 vs 17%, p = 0.045 and 26 vs 38%, p = 0.029, respectively). Levosimendan produced less myocardial ischemia and cardiac arrhythmias than dobutamine. Calcium sensitizers offer a new therapeutic possibility in patients with decompensated low-output heart failure.

The clinical experience with levosimendan in anesthesiology and in the intensive care unit.

In the present review striking data showing that intensive care unit patients with acute heart failure and high-risk surgical patients may markedly benefit from the use of levosimendan are presented. Indeed, levosimendan is an effective new agent that acts via two complementary mechanisms. It enhances cardiac contractility by improving the response of the myofilaments to intracellular calcium, and it reduces the cardiac workload by opening the adenosine triphosphate-dependent potassium channels for the dilation of blood vessels. Because the therapeutic levels of levosimendan do not increase the intracellular calcium concentrations, levosimendan is less likely than traditional inotropes (beta-agonist inotropes or phosphodiesterase inhibitors) to elicit arrhythmias or impair diastolic relaxation. In fact, the results of recent clinical studies indicate that levosimendan offers significant hemodynamic and survival benefits when given to patients who are hospitalized for acute heart failure. Indeed, in the near future, it is likely that levosimendan may also prove effective for the treatment of patients with diastolic heart failure or for those with a low cardiac output following coronary artery bypass grafting. In addition, levosimendan has the potential of supporting the cardiac function during the initiation of beta-blocker therapy, for weaning patients from cardiopulmonary bypass, for individuals with valvular abnormalities and for those with myocarditis. Preliminary results also suggest that levosimendan may be beneficial for the treatment of patients with right ventricular heart failure. Although the use of levosimendan has been fully validated for the most common causes of acute heart failure, additional clinical trials are needed to safety broaden its therapeutic indications.

Reperfusion-induced arrhythmias are suppressed by inhibition of the angiotensin II type 1 receptor.

We examined antiarrhythmic effects of drugs, including renin-angiotensin system (RAS) inhibitors, on reperfusion arrhythmias in rats in vivo. Anesthetized rats were subjected to 5 min of coronary occlusion and 30 min of reperfusion. Arrhythmia scores, calculated as the product of the type of arrhythmia (1 for ventricular tachycardia, 2 for ventricular fibrillation) and its duration (in seconds), were adopted to evaluate the severity of arrhythmias. Reperfusion arrhythmias were suppressed by Na(+)/H(+) exchange inhibitor, Na(+)/Ca(2+) exchange inhibitor and L-type Ca channel antagonist by more than 90%. Angiotensin-converting enzyme inhibitor and angiotensin II (Ang II) type 1 receptor (AT(1)) antagonist also modestly (by 60-70%) but significantly decreased reperfusion arrhythmias. These effects were not reversed by co-administration of bradykinin B(2) receptor antagonist or AT(2) antagonist, respectively. Effects of superoxide dismutase (SOD) were also examined, but SOD proved ineffective. Effects of Na(+)/H(+) exchange inhibitor, Na(+)/Ca(2+) exchange inhibitor and L-type Ca channel antagonist suggest a causative relationship of Ca overload in reperfusion arrhythmias. These transport systems are known to be activated by Ang II. Thus, the antiarrhythmic action of RAS inhibitors might be attributable to the inhibition of the action of Ang II via AT(1).