Antidiarrheal and Cardio-Depressant Effects of Himalaiella heteromalla (D.Don) Raab-Straube: In Vitro, In Vivo, and In Silico Studies

Himalaiella heteromalla (D.Don) Raab-Straube is a commonly used remedy against various diseases. Crude extract and fractions of H. heteromalla were investigated for a gastrointestinal, bronchodilator, cardiovascular, and anti-inflammatory activities. H. heteromalla crude extract (Hh.Cr) relaxed spontaneous contractions and K+ (80 mM)-induced contraction in jejunum tissue dose-dependently. The relaxation of K+ (80 mM) indicates the presence of Ca++ channel blocking (CCB) effect, which was further confirmed by constructing calcium response curves (CRCs) as they caused rightward parallel shift of CRCs in a manner comparable to verapamil, so the spasmolytic effect of Hh.Cr was due to its CCB activity. Application of Hh.Cr on CCh (1 µM) and K+ (80 mM)-induced contraction in tracheal preparation resulted in complete relaxation, showing its bronchodilator effect mediated through Ca++ channels and cholinergic antagonist activity. Application of Hh.Cr on aortic preparations exhibited vasorelaxant activity through angiotensin and α-adrenergic receptors blockage. It also showed the cardio suppressant effect with negative chronotropic and inotropic response in paired atrium preparation. Similar effects were observed in in vivo models, i.e., decreased propulsive movement, wet feces, and inhibition of edema formation.

Reversal of Bortezomib-Induced Neurotoxicity by Suvecaltamide, a Selective T-Type Ca-Channel Modulator, in Preclinical Models

This study evaluated suvecaltamide, a selective T-type calcium channel modulator, on chemotherapy-induced peripheral neurotoxicity (CIPN) and anti-cancer activity associated with bortezomib (BTZ). Rats received BTZ (0.2 mg/kg thrice weekly) for 4 weeks, then BTZ alone (n = 8) or BTZ+suvecaltamide (3, 10, or 30 mg/kg once daily; each n = 12) for 4 weeks. Nerve conduction velocity (NCV), mechanical threshold, β-tubulin polymerization, and intraepidermal nerve fiber (IENF) density were assessed. Proteasome inhibition was evaluated in peripheral blood mononuclear cells. Cytotoxicity was assessed in human multiple myeloma cell lines (MCLs) exposed to BTZ alone (IC50 concentration), BTZ+suvecaltamide (10, 30, 100, 300, or 1000 nM), suvecaltamide alone, or vehicle. Tumor volume was estimated in athymic nude mice bearing MCL xenografts receiving vehicle, BTZ alone (1 mg/kg twice weekly), or BTZ+suvecaltamide (30 mg/kg once daily) for 28 days, or no treatment (each n = 8). After 4 weeks, suvecaltamide 10 or 30 mg/kg reversed BTZ-induced reduction in NCV, and suvecaltamide 30 mg/kg reversed BTZ-induced reduction in IENF density. Proteasome inhibition and cytotoxicity were similar between BTZ alone and BTZ+suvecaltamide. BTZ alone and BTZ+suvecaltamide reduced tumor volume versus the control (day 18), and BTZ+suvecaltamide reduced tumor volume versus BTZ alone (day 28). Suvecaltamide reversed CIPN without affecting BTZ anti-cancer activity in preclinical models.

Expression and roles of N-type Ca channel in cardiaomyocytes

Background Voltage dependent Ca channels are divided to L-, T-, N-, P/Q-, and R-types, and N-type Ca channel (NCC) is mainly expressed in nerve terminal and regulates neurotransmitter release. Recently, NCC has been reported to express in adrenal gland and renal tubular cells. We examined whether NCC is expressed in cardiac myocytes and if so, the roles of this channel. Methods Expression of NCC mRNA and protein in cardiomyocytes were assessed by quantitative real time PCR and Western blot analysis using neonatal rat cultured cardiomyocytes, infant, and adult rat hearts. Expression site of NCC in cardiomyocytes was examined by confocal imaging of immunofluorescent staining. The roles of NCC in physiological Ca transient in neonatal myocytes were examined using fluorescence imaging of Fluo4, an intracellular Ca indicator. To examine the effects of pathological condition, such as heart failure and ischemia-reperfusion, on NCC expression, cultured cardiomyocytes were treated with norepinephrine (10 μmol/L, 24 hours) or subjected to 5 hours of hypoxia followed by 30 minutes of reoxygenation. In addition, adult rats were subjected to myocardial infarction by ligating the left anterior coronary artery. Lethal myocyte injury was examined by LDH activity in culture medium and myocyte apoptosis was examined by nuclear staining with DAPI and caspase 3 activity. To clarify the roles of NCC in neonatal myocytes in these pathological conditions, we examine the effect of ω-conotoxin, a selective NCC blocker. Results NCC mRNA and protein were expressed in neonatal cardiomyocytes. Immunocytochemical staining showed NCC was expressed in myocyte plasma membrane. During physiological spontaneous beating, ω-conotoxin did not affect beating rate and intra cellular Ca transient, suggesting that the roles of NCC on physiological beating are little. After birth level of NCC mRNA expression in cardiac tissue gradually decreased within 2 weeks and low level of mRNA expressed continuously in adult cardiac tissue. However, in pathological condition, mRNA and protein levels of NCC in non-infarcted region were increased 4 weeks after myocardial infarction. In addition, hypoxia-reoxygenation and norepinephrine administration increased LDH release and myocyte apoptosis in association with increase in NCC expression in neonatal cultured myocytes. ω-conotoxin significantly suppressed hypoxia/reoxygenation- and norepinephrine-induced LDH release and caspase 3 activation. Conclusion NCC is expressed in neonatal cardiac myocytes and the expression level was decreased after birth. Pathological condition, such as ischemic heart disease and heart failure, upregulated NCC expression in cardiomyocytes and NCC exacerbated lethal myocyte injury, while roles of NCC in physiological beating are little. FUNDunding Acknowledgement Type of funding sources: None.

Visualization of Ca Channel Blocker on Human Adrenal Tissue by Mass Spectrometry Imaging ~Its Predominant Distribution at Aldosterone-Producing Cells ~

Primary aldosteronism (PA) is the main cause of secondary hypertension, accounting for approximately 5–10% of all hypertension. Amlodipine, a third-generation calcium channel blocker, is one of the most frequently administered pharmaceuticals medications of hypertension, binds specifically to Cav1.2, a calcium channel primarily localized in the cardiovascular system, and exerts antihypertensive effects through inhibiting calcium influx into the vascular smooth muscle cells. In addition, calcium influx also plays important roles in aldosterone production and amlodipine was also reported to influence in vitro functions of Cav1.3, a calcium channel involved in aldosterone secretion. Ca channel blockers were also reported to reduce plasma aldosterone concentration by some clinical studies although with mild degrees. However, in vivo effects of amlodipine to aldosterone secretion has remained virtually unknown. A novel technique “Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry Imaging (MALDI-MSI)” has been recently developed, which did make it possible to visualize non-labeled small molecules on tissue sections. Therefore, in this study, we firstly applied MALDI-MSI to visualize amlodipine on human adrenal glands including aldosterone producing adenoma (APA). We performed selective imaging of amlodipine using MALDI-MSI on the resected adrenal tissues from APA patients. Frozen sections containing whole representative tumor area were coated with a matrix called CHCA (α-Cyano-4-hydroxycinnamic acid) by deposition as a pretreatment. We subsequently analyzed and detected a precursor ion with MS at m/z 407.1 and then an amlodipine-specific ion with MS/MS at m/z 318.1. We also examined the concordance of amlodipine distribution obtained by this method with immunohistochemistry. Human resected adrenal tissues obtained from the patients APAs treated with and without amlodipine before adrenalectomy were examined. Periadrenal adipose tissues were also analyzed as a control tissue of non-aldosterone-producing tissues. Amlodipine was specifically detected and visualized only in the administered cases. Amlodipine was more abundantly detected in adrenal tissues than periadrenal adipose tissues. On the other hand, significant different was not detected between tumors and adjacent adrenal glands by semi-quantification using MALDI-MSI. In this study, we firstly visualized amlodipine directly in human tissue sections using MALDI-MSI. Increased accumulation of amlodipine in APAs treated with amlodipine did indicate direct effects of amlodipine on aldosterone production but further investigations are required for clarification between neoplastic and non-neoplastic aldosterone producing cells.

Qtc Prolongation as Prognostic Marker in Organophosphate Poisoning

Background The long QT syndrome (LQTS) is a disorder of myocardial repolarization characterized by a prolonged QT interval on the electrocardiogram (ECG). This syndrome is associated with an increased risk of polymorphic ventricular tachycardia, a characteristic life-threatening cardiac arrhythmia also known as torsades de pointes. A rate related corrected QT interval (QTc) can be calculated as QT/√RR and normally is ≤0.44s. Some references given QTc upper normal limits as 0.43s in men and 0.45s in female. OP compound supposed to block K+ channel and Na+/Ca++ channel and hence causing prolongation of QT interval. As we know that prolongation of QT interval may precipitate polymorphic ventricular tachycardia and sudden cardiac death, so it become important in case of OP poisoning and related mortality. In this study, I calculated corrected QT interval in diagnosed cases of OP poisoning admitted at Bir Hospital and compared QTc among those with complications and without complication. I also tried to evaluate QTc as a predictor for duration of hospital stays, ICU admission, vasopressor and mechanical ventilation requirement, higher POP score and low GCS.

Homeostatic plasticity and burst activity are mediated by hyperpolarization-activated cation currents and T-type calcium channels in neuronal cultures

Homeostatic plasticity stabilizes neuronal networks by adjusting the responsiveness of neurons according to their global activity and the intensity of the synaptic inputs. We investigated the homeostatic regulation of hyperpolarization-activated cyclic nucleotide-gated (HCN) and T-type calcium (CaV3) channels in dissociated and organotypic slice cultures. After 48 h blocking of neuronal activity by tetrodotoxin (TTX), our patch-clamp experiments revealed an increase in the depolarizing voltage sag and post-inhibitory rebound mediated by HCN and CaV3 channels, respectively. All HCN subunits (HCN1 to 4) and T-type Ca-channel subunits (CaV3.1, 3.2 and 3.3) were expressed in both control and activity-deprived hippocampal cultures. Elevated expression levels of CaV3.1 mRNA and a selective increase in the expression of TRIP8b exon 4 isoforms, known to regulate HCN channel localization, were also detected in TTX-treated cultured hippocampal neurons. Immunohistochemical staining in TTX-treated organotypic slices verified a more proximal translocation of HCN1 channels in CA1 pyramidal neurons. Computational modeling also implied that HCN and T-type calcium channels have important role in the regulation of synchronized bursting evoked by previous activity-deprivation. Thus, our findings indicate that HCN and T-type Ca-channels contribute to the homeostatic regulation of excitability and integrative properties of hippocampal neurons.