Isradipine therapy in Cacna1dIle772Met/+ mice ameliorates primary aldosteronism and neurologic abnormalities.

Somatic gain-of-function mutations in the L-type calcium channel CaV1.3 (CACNA1D gene) cause adrenal aldosterone-producing adenomas and micronodules. De novo germline mutations are found in a syndrome of primary aldosteronism, seizures, and neurologic abnormalities (PASNA) as well as in autism spectrum disorder. Using CRISPR/Cas9, we here generated mice with a Cacna1d gain-of-function mutation found in both adenomas and PASNA syndrome (Cacna1dIle772Met/+). These mice show reduced body weight and increased mortality from weaning to approximately 100 days of age. Male mice do not breed, likely due to neuromotor impairment, and the offspring of female mice die perinatally, likely due to lack of maternal care. Mice generated by in vitro fertilization showed elevated intracellular calcium in the aldosterone-producing zona glomerulosa, an elevated aldosterone/renin ratio, and persistently elevated serum aldosterone on a high-salt diet as signs of primary aldosteronism. Anesthesia with ketamine and xylazine induced tonic-clonic seizures. Neurologic abnormalities included hyperlocomotion, impaired performance in the rotarod test, impaired nest building, and slight changes in social behavior. Intracellular calcium in the zona glomerulosa, aldosterone levels, and rotarod performance responded to treatment with the calcium channel blocker isradipine, with implications for the therapy of patients with aldosterone-producing lesions and with PASNA syndrome.

Formulation and Evaluation of Isradipine Nanosuspension and Exploring its Role as a Potential Anticancer Drug by Computational Approach.

BACKGROUND: T-type calcium channels are aberrantly expressed in different human cancers and regulate cell cycle progression, proliferation, migration, and survival. FAK-1 can promote tumor protein degradation (p53) through ubiquitination, leading to cancer cell growth and proliferation. Similar findings are obtained regarding protease inhibitors' effect on cytokine-induced neutrophil activation that suppresses Granulocyte-macrophage colony-stimulatingfactor (GM-CSF) TNF-α-induced O2 release and adherence in human neutrophils without affecting phosphorylation of Extracellular signal-regulated kinase (ERK) and p38. Nanosuspensions are carrier-free, submicron colloidal dispersions, which consist of pure drugs and stabilizers. Incorporating drug loaded in nanosuspensions offer a great advantages of passive drug targeting with improved solubility, stability, and bioavailability, as well as lower systemic toxicity. OBJECTIVE: The present investigation objective was to establish a molecular association of Protease and Focal Adhesion Kinase 1 as cancer targets for isradipine, a calcium channel blocker (CCB). Furthermore, the study also aimed to formulate its optimized nanosuspension and how the physical, morphological, and dissolution properties of isradipine impact nanosuspension stability. METHODS: Five different molecular targets, namely Cysteine Proteases (Cathepsin B), Serine Proteases (Matriptase), Aspartate Proteases, Matrix Metalloproteases (MMP), and FAK-1 were obtained from RCSB-PDB, which has some potential associations with inhibition in cancer pathogenesis. Molecular interactions of these targets with CCB isradipine were identified and established by molecular simulation docking studies. Isradipine-loaded nanosuspension was prepared by precipitation technique by employing a 23 factorial design. PVP K-30, poloxamer 188, and sodium lauryl sulfate (SLS) were used as polymer, co-polymer, and surfactant, respectively. The nanosuspension particles were assessed for particle size, zeta potential, viscosity, polydispersity index (PDI), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), In-vitro drug release kinetics, and short-term stability study. RESULTS: Considerable interactions were found with Cysteine, Serine, Aspartate, Threonine, and Matrix metalloproteases with binding energies of -3.91, -6.7, -3.48, -8.42, respectively. Furthermore, the interaction of isradipine with FAK-1 was compared with 7 native ligands and was found to show significant interaction with binding energies of - 8.62, -7.27, -7.69, -5.67, -5.41, -7.44, -8.21, respectively. The optimized nanosuspension was evaluated and exhibited a particle size of 754.9 nm, zeta potential of 32.5 mV, viscosity of 1.287 cp, and PDI of 1.000. The In-vitro dissolution of the optimized formulation (F8) was found to be higher (96.57%) as compared to other formulations. CONCLUSION: Isradipine could act as a potential inhibitor of different proteases and FAK-1 associated with tumor growth initiation, progression, and metastasis. Furthermore, isradipine-loaded nanosuspension with optimized release could be utilized to deliver the anticancer drug in a more targeted way as emerging cancer nanotechnology.

Adjunctive Raloxifene and Isradipine Improve Cognitive Functioning in Patients With Schizophrenia: A Pilot Study.

BACKGROUND: Cognitive impairment is the most important feature of schizophrenia leading to severe functional disability. To identify pathways that improve pathophysiological neurocognition in schizophrenia is a current challenge for the development of goal-directed clinical interventions. In the present study, we investigated the effects of raloxifene (a selective estrogen modulator) and isradipine (a voltage-gated L-type calcium channel blocker) on cognitive deficits in patients with schizophrenia. METHOD: We designed a double-blind, randomized, parallel, placebo-controlled trial. We randomized 60 patients with schizophrenia into 3 groups including isradipine 5 mg, raloxifine 60 mg, and placebo for 6 consequent weeks, all in the same shape capsules, 2 times a day, along with treatment as usual. The initial and final results of blood tests, electrocardiograms, and cognitive tests in specific domains, such as attention, processing speed, executive function, and verbal memory were evaluated. RESULTS: Our findings revealed a remarkable association between adjunctive raloxifene treatment and the alleviation of verbal memory deficits. Isradipine treatment significantly improved the verbal memory and attention dysfunction in some variables of the Stroop test, compared with the placebo. However, no effect was observed in processing speed and executive function deficits. CONCLUSIONS: To the best of our knowledge, this study provides the first evidence that isradipine is a novel therapy option improving verbal memory and attention, both related to its activity in the hippocampus and the cerebellum. Further investigations are necessary to elucidate the mechanisms of action for both drugs in schizophrenia.

Isradipine enhancement of virtual reality cue exposure for smoking cessation: Rationale and study protocol for a double-blind randomized controlled trial.

Cigarette smoking remains a leading cause of preventable death in the United States, contributing to over 480,000 deaths each year. Although significant strides have been made in the development of effective smoking cessation treatments, most established interventions are associated with high relapse rates. One avenue for increasing the effectiveness of smoking cessation interventions is to design focused, efficient, and rigorous experiments testing engagement of well-defined mechanistic targets. Toward this aim, the current protocol will apply a pharmacologic augmentation strategy informed by basic research in animal models of addiction. Our goal is to evaluate the enhancing effect of isradipine, an FDA-approved calcium channel blocker, on the extinction of craving-a key mechanism of drug relapse after periods of abstinence. To activate craving robustly in human participants, we will use multimodal smoking cues including novel 360° video environments developed for this project and delivered through consumer virtual reality headsets. Adult smokers will take either isradipine or placebo and complete the cue exposure protocol in a double-blind randomized control trial. In order to test the hypothesis that isradipine will enhance retention of craving extinction, participants will repeat cue exposure 24 h later without the administration of isradipine or placebo. The study will be implemented in a primary care setting where adult smokers receive healthcare, and smoking behavior will be tracked throughout the trial with ecological momentary assessment.

L-type Calcium Channels are Involved in Iron-induced Neurotoxicity in Primary Cultured Ventral Mesencephalon Neurons of Rats.

In the present study, we investigated the mechanisms underlying the mediation of iron transport by L-type Ca2+ channels (LTCCs) in primary cultured ventral mesencephalon (VM) neurons from rats. We found that co-treatment with 100 µmol/L FeSO4 and MPP+ (1-methyl-4-phenylpyridinium) significantly increased the production of intracellular reactive oxygen species, decreased the mitochondrial transmembrane potential and increased the caspase-3 activation compared to MPP+ treatment alone. Co-treatment with 500 µmol/L CaCl2 further aggravated the FeSO4-induced neurotoxicity in MPP+-treated VM neurons. Co-treatment with 10 µmol/L isradipine, an LTCC blocker, alleviated the neurotoxicity induced by co-application of FeSO4 and FeSO4/CaCl2. Further studies indicated that MPP+ treatment accelerated the iron influx into VM neurons. In addition, FeSO4 treatment significantly increased the intracellular Ca2+ concentration. These effects were blocked by isradipine. These results suggest that elevated extracellular Ca2+ aggravates iron-induced neurotoxicity. LTCCs mediate iron transport in dopaminergic neurons and this, in turn, results in elevated intracellular Ca2+ and further aggravates iron-induced neurotoxicity.

A novel transgenic zebrafish line allows for in vivo quantification of autophagic activity in neurons.

The pathophysiology of most neurodegenerative diseases includes aberrant accumulation of protein aggregates. Recent evidence highlights the role of protein degradation pathways in neurodegeneration. Concurrently, genetic tools have been generated to enable zebrafish, Danio rerio, to be used as an animal model to study neurodegenerative processes. In addition to optical clarity and fast ex utero development, the zebrafish brain is relatively small and has conserved structures with its mammalian counterparts. To take advantage of this model organism and to aid further studies on autophagy and neurodegeneration, we created a stable transgenic zebrafish line that expresses eGFP-Map1lc3b specifically in post-mitotic neurons under the elavl3 promoter. This line is useful for indirectly monitoring autophagic activity in neurons in vivo and screening for macroautophagy/autophagy-modulating compounds. We determined the applicability of this transgenic line by modulating and quantifying the number of autophagosomes via treatment with a known autophagy inducer (rapamycin) and inhibitors (3-methyladenine, protease inhibitors). Additionally, we proposed an in vivo method for quantifying rates of autophagosome accumulation, which can be used to infer occurrence of autophagic flux. Last, we tested two FDA-approved drugs currently undergoing clinical studies for Parkinson disease, isradipine and nilotinib, and found that isradipine did not modulate autophagy, whereas nilotinib induced both autophagosome number and autophagic flux. It is hoped that others will find this line useful as an in vivo vertebrate model to find or validate autophagy modulators that might be used to halt the progression of neurodegenerative diseases. Abbreviations: 3MA: 3-methyladenine; BafA: bafilomycin A1; dd: dorsal diencephalon; dpf: days post fertilization; e: eye; eGFP: enhanced green fluorescent protein; Elavl3: ELAV like neuron-specific RNA binding protein 3; FDA: Food and Drug Administration; hb: habenula; hpt, hours post treatment; Map1lc3b: microtubule-associated protein 1 light chain 3 beta; nt: neural tube; ot, optic tectum; P/E: pepstatin A and E64d; PD: Parkinson disease; PMTs: photomultiplier tubes; PTU: 1-phenyl-2-thiourea; Ta: annealing temperature; Tel, telencephalon.

Isradipine attenuates MPTP-induced dopamine neuron degeneration by inhibiting up-regulation of L-type calcium channels and iron accumulation in the substantia nigra of mice.

The aim of this study is to investigate the effects of L-type calcium channels (LTCCs) on MPTP-induced dopamine (DA) neuron degeneration and iron accumulation in the substantia nigra (SN) of mice. By real-time PCR and western blots, we first quatified expressions of L-type Cav1.2 and Cav1.3 calcium channel α1 subunits in the SN of experimental mice treated with MPTP. We found that the expressions of Cav1.2 and Cav1.3 calcium channel α1 subunits markedly increased after MPTP treatment for 2 and 3 weeks. Secondly, we observed the effects of isradipine, a LTCC antagonist, on MPTP-induced DA neuron degeneration and iron accumulation in the SN. Our results showed that isradipine treatment prevented against MPTP-induced Cav1.2 and Cav1.3 calcium channel α1 subunits up-regulation in the SN. We also found that isradipine prevented against MPTP-induced DA neuron depletion in the SN and partly restored the DA content in the striatum. Moreover, we found that isradipine inhibited the increase of iron positive cells in the SN of the MPTP-treated mice. Finally, we investigated the effects of isradipine on cellular iron accumulation in the dopaminergic MES23.5 cell line. Our studies showed that MPP+ treatment accelerated iron influx in the MES23.5 cells. Treatment with Bayk8644 further aggravated iron accumulation. Treatment with isradipine prevented against MPP+-induced iron influx in the MES23.5 cells. These results suggest that up-regulation of LTCCs may be responsible for the DA neuron degeneration in the MPTP-treated mice, The LTCCs may directly contribute to iron influx into DA neurons, and isradipine may suppress cellular iron accumulation and prevents neurodegeneration.

Nifedipine and nimodipine protect dopaminergic substantia nigra neurons against axotomy-induced cell death in rat vibrosections via modulating inflammatory responses.

Neurodegeneration of cholinergic and dopaminergic neurons is a major hallmark in Alzheimer's or Parkinson's disease, respectively. A dysregulation in calcium homeostasis may be part of this process and counteracting calcium influx may have neuroprotective properties in both diseases. Therefore, we investigated the putative neuroprotective or neurotoxic activity of L-type calcium channel (LTCC) inhibitors on cholinergic and dopaminergic neurons in a rat organotypic vibrosection model. Sagittal or coronal vibrosections (200 µm thick) of postnatal day 10 rats were cultured on 0.4 µm semipermeable membranes for 2 weeks with 10 ng/ml nerve growth factor (NGF) and/or glial-cell line derived neurotrophic factor (GDNF) to maintain survival of cholinergic or dopaminergic neurons, respectively. Thereafter, sections were incubated with 0.1, 1 or 10 µM isradipine, nicardipine or verapamil for 2 weeks to explore cytotoxicity. Alternatively, in order to explore neuroprotective activity, vibrosections were incubated without growth factors but with isradipine or verapamil or with nicardipine, nimodipine or nifedipine from the beginning for 4 weeks. Our data show that all LTCC inhibitors exhibited no neurotoxic effect on cholinergic and dopaminergic neurons. Further, LTCC inhibitors did not have any neuroprotective activity on cholinergic neurons. However, nimodipine and nifedipine significantly enhanced the survival of dopaminergic substantia nigra (SN) but not ventral tegmental area (VTA) neurons, while nicardipine, isradipine and verapamil had no effect. Nifedipine (and more potently GDNF) reduced inflammatory cytokines (macrophage inflammatory protein-2, tumor necrosis factor-α), but did not influence oxidative stress or caspase-3 activity and did not interfere with iron-mediated overload. Our data show that nifedipine and nimodipine are very potent to enhance the survival of axotomized SN neurons, possibly influencing inflammatory processes.

Isradipine prevents rotenone-induced intracellular calcium rise that accelerates senescence in human neuroblastoma SH-SY5Y cells.

Previous research demonstrated that rotenone (RT) induces neuronal injury partially by increasing intracellular Ca(2+) concentrations ([Ca(2+)]i), and inducing oxidative stress, leading to a neurodegenerative disorder. However, the mechanism of RT-induced injury remains elusive. Recent work revealed that Ca(2+) signaling is important for RT-induced senescence in human neuroblastoma SH-SY5Y cells. In the present study, we found that in SH-SY5Y cells, RT increased [Ca(2+)]i, senescence associated ß-galactosidase activity, aggregation of lipofuscin, production of reactive oxygen species, G1/G0 cell cycle arrest, and activation of p53/p21 signaling proteins. In addition, RT decreased the expression of the signaling proteins for cell proliferation and survival, Cyclin-dependent kinase 2 (CDK2), cyclin D1, and Akt. Pretreatment of SH-SY5Y cells with isradipine, an L-type Ca(2+) channel blocker, or EGTA antagonized these effects of RT. These results suggested that application of isradipine might be a novel approach to prevent RT-induced neurodegenerative disorder such as Parkinson's disease.

Effect of hydrophilic polymers on isradipine complexation with hydroxypropyl ß-cyclodextrin.

Complexation of isradipine with hydroxypropyl ß-cyclodextrin (HPßCD) in the presence and absence of 3 hydrophilic polymers-polyvinyl pyrrolidone (PVP), hydroxypropyl methylcellulose (HPMC), and polyethylene glycol (PEG)-was investigated with an objective of evaluating the effect of hydrophilic polymers on the complexation and solubilizing efficiencies of HPßCD and on the dissolution rate of isradipine from the HPßCD complexes. The phase solubility studies indicated the formation of isradipine-HPßCD inclusion complexes at a 1:1M ratio in solution in both the presence and the absence of hydrophilic polymers. The complexes formed were quite stable. Addition of hydrophilic polymers markedly improved the complexation and solubilizing efficiencies of HPßCD. Solid inclusion complexes of isradipine-HPßCD were prepared in 1:1 and 1:2 ratios by the kneading method, with and without the addition of hydrophilic polymers. The solubility and dissolution rate of isradipine were significantly improved by complexation with HPßCD. The isradipine-HPßCD (1:2) inclusion complex yielded a 9.66-fold increase in the dissolution rate of isradipine. The addition of hydrophilic polymers also markedly improved the dissolution rate of isradipine from HPßCD complexes: a 11.72-, 17.01-, and 39.23-fold increase was observed with PVP, PEG, and HPMC respectively. X-ray diffractometry and differential scanning calorimetry indicated stronger drug amorphization and entrapment in HPßCD because of the combined action of HPßCD and the hydrophilic polymers.

A translational continuum of model systems for evaluating treatment strategies in Alzheimer's disease: isradipine as a candidate drug.

A growing body of evidence supports the 'calcium hypothesis' of Alzheimer's disease (AD), which postulates that a variety of insults might disrupt the homeostatic regulation of neuronal calcium (Ca(2+)) in the brain, resulting in the progressive symptoms that typify the disease. However, despite ongoing efforts to develop new methods for testing therapeutic compounds that might be beneficial in AD, no single bioassay permits both rapid screening and in vivo validation of candidate drugs that target specific components of the Ca(2+) regulatory machinery. To address this issue, we have integrated four distinct model systems that provide complementary information about a trial compound: the human neuroblastoma MC65 line, which provides an in vitro model of amyloid toxicity; a transgenic Drosophila model, which develops age-dependent pathologies associated with AD; the 3×TgAD transgenic mouse, which recapitulates many of the neuropathological features that typify AD; and the embryonic nervous system of Manduca, which provides a novel in vivo assay for the acute effects of amyloid peptides on neuronal motility. To demonstrate the value of this 'translational suite' of bioassays, we focused on a set of clinically approved dihydropyridines (DHPs), a class of well-defined inhibitors of L-type calcium channels that have been suggested to be neuroprotective in AD. Among the DHPs tested in this study, we found that isradipine reduced the neurotoxic consequences of ß-amyloid accumulation in all four model systems without inducing deleterious side effects. Our results provide new evidence in support of the Ca(2+) hypothesis of AD, and indicate that isradipine represents a promising drug for translation into clinical trials. In addition, these studies also demonstrate that this continuum of bioassays (representing different levels of complexity) provides an effective means of evaluating other candidate compounds that target specific components of the Ca(2+) regulatory machinery and that therefore might be beneficial in the treatment of AD.

L-type voltage-gated calcium channel blockade with isradipine as a therapeutic strategy for Alzheimer's disease.

There is strong evidence that intracellular calcium dysregulation plays an important pathological role in Alzheimer's disease, and specifically that beta amyloid may induce increases in intracellular calcium and lead to neuronal cell dysfunction and death. Here we investigated the feasibility of modifying Alzheimer's pathology with the L-type voltage-gated calcium channel blockers verapamil, diltiazem, isradipine and nimodipine. All four compounds protected MC65 neuroblastoma cells from amyloid beta protein precursor C-terminal fragment (APP CTF)-induced neurotoxicity. Isradipine was the most potent blocker, preventing APP CTF neurotoxicity at nanomolar concentrations. Intracellular beta amyloid expression was associated with increased expression of Cav 1.2 calcium channels and increased intracellular calcium influx from the extracellular space. Despite the cytoprotection afforded by calcium channel blockers, amyloid beta oligomer formation was not suppressed. The mechanism of cell death in MC65 cells is appeared to be caspase-3 independent. With the goal of determining if there is sufficient experimental support to move forward with animal trials of isradipine, we determined its bioavailability in the triple transgenic mouse model of AD. Subcutaneous implantation of carrier-bound isradipine (3 µg/g/day) for 60 days resulted in nanomolar concentrations in both the plasma and brain. Taken together, our in vitro results support the theory that calcium blockers exert protective effects downstream of the effects of beta amyloid. Isradipine's neuroprotective effect at concentrations that are clinically relevant and achievable in vitro and in vivo suggests that this particular calcium blocking agent may have therapeutic value in the treatment of Alzheimer's disease.

Isradipine for treatment of acute hypertension in hospitalized children and adolescents.

Severe acute hypertension in pediatric patients requires prompt and controlled blood pressure (BP) reduction to prevent end-organ damage. The authors aimed to examine the efficacy and safety of isradipine, an orally administered second-generation dihydropyridine calcium channel blocker, for treatment of acute hypertension in hospitalized pediatric patients. A retrospective analysis of 391 doses of isradipine administered to 282 patients (58% boys) with acute hypertension and median age of 12.8 years (range, 0.1-21.9) was performed. Primary diagnoses included renal disease (n=154), malignancy (45), nonrenal transplant (37), neurologic disease (21), and other (25). The decrease in systolic BP was 16.3%±11.6% (mean ± SD) and diastolic BP was 24.2%±17.2%. BPs were significantly lower in all age groups and in all diagnosis categories following isradipine administration. The decrease in BP was the highest in children younger than 2 years. The mean increase in pulse after a dose was 7±17 beats per minute. Forty adverse events were reported in 33 patients, with emesis and nausea being the most common; 5 of these events were hypotension. The authors conclude that isradipine effectively reduces BP in a wide variety of hospitalized children and adolescents with acute hypertension. A lower initial dose of 0.05 mg/kg may be appropriate in children younger than 2 years.

CaV1.2 rather than CaV1.3 is coupled to glucose-stimulated insulin secretion in INS-1 832/13 cells.

In clonal beta-cell lines and islets from different species, a variety of calcium channels are coupled to glucose-stimulated insulin secretion. The aim of this study was to identify the voltage-gated calcium channels that control insulin secretion in insulinoma (INS)-1 832/13 cells. The mRNA level of Ca(V)1.2 exceeded that of Ca(V)1.3 and Ca(V)2.3 two-fold. Insulin secretion, which rose tenfold in response to 16.7 mM glucose, was completely abolished by 5 microM isradipine that blocks Ca(V)1.2 and Ca(V)1.3. Similarly, the increase in intracellular calcium in response to 15 mM glucose was decreased in the presence of 5 microM isradipine, and the frequency of calcium spikes was decreased to the level seen at 2.8 mM glucose. By contrast, inhibition of Ca(V)2.3 with 100 nM SNX-482 did not significantly affect insulin secretion or intracellular calcium. Using RNA interference, Ca(V)1.2 mRNA and protein levels were knocked down by approximately 65% and approximately 34% respectively, which reduced insulin secretion in response to 16.7 mM glucose by 50%. Similar reductions in calcium currents and cell capacitance were seen in standard whole-cell patch-clamp experiments. The remaining secretion of insulin could be reduced to the basal level by 5 microM isradipine. Calcium influx underlying this residual insulin secretion could result from persisting Ca(V)1.2 expression in transfected cells since knock-down of Ca(V)1.3 did not affect glucose-stimulated insulin secretion. In summary, our results suggest that Ca(V)1.2 is critical for insulin secretion in INS-1 832/13 cells.

[Experimental investigations of the analgesic activity of fentanyl and the non-opiodal agents -clonidine and isradipine, and protease inhibitors].

The analgesic activity of clonidine, isradipine, antagosane (aprotinine), transamine, and their combinations with fentanyl in subanalgesic doses was experimentally studied on mice, by using the tail-flick test. Analgesic activity was found in clonidine, antagosane, and transamine. A combination of fentanyl used in subanalgesic doses and clonidine, isradipine, antagosane, or transamine had supertotal analgesic activity. The findings serve as a basis for effectively making up a component of analgesia during anesthetic support at surgery made in patients with baseline sympathicotonia, ischemia/reperfusion syndrome, and a systemic inflammatory reaction.

A review of calcium channel antagonists in the treatment of pediatric hypertension.

All children aged > or = 3 years should have an annual blood pressure (BP) measurement taken during a routine physical examination. Physicians should become familiar with recommended pediatric normative BP tables. BP above the 95th percentile may require drug therapy. There are several categories of antihypertensives available to the clinician. Calcium channel antagonists (CCAs) are a class of drugs that exert their antihypertensive effect by inhibiting the influx of calcium ions across the cell membranes. This results in dilatation of peripheral arterioles. When given orally, CCAs are metabolised in the liver by cytochrome P450 (CYP) enzyme CYP3A4; hence, some CCAs will affect the half-life of drugs that share this enzyme system for their metabolism. CCAs can be safely used in children with renal insufficiency or failure and as a general rule there is no need to modify drug dosage in this population. CCAs are generally well tolerated; most adverse effects appear to be dose related. Headache, flushing, gastrointestinal upset, and edema of the lower extremities are the most common symptoms reported with the use of CCAs. Pediatric data regarding safety and efficacy of CCAs have mostly been obtained from retrospective analyses. Extended-release nifedipine and amlodipine are the two most commonly used oral CCAs in the management of pediatric hypertension. These drugs can be given once a day, although many children require twice-daily administration. Extended-release nifedipine has to be swallowed whole; hence, its use in younger children who cannot swallow pills is limited. Amlodipine can be made into a solution without compromising its long duration of action; therefore, it is the CCA of choice for very young children. Oral short-acting nifedipine and intravenous nicardipine are safe and effective CCAs for the management of hypertensive crisis in children. Short-acting nifedipine can cause unpredictable changes in BP; hence, it should be used cautiously and in low doses. Intravenous nicardipine has a rapid onset of action and a short half-life. Intravenous infusion of nicardipine can be titrated for effective control of BP. Intravenous nicardipine has been used safely in hospitalized children and newborns for the management of hypertensive crisis, and for controlled hypotension during surgery. CCAs are a class of antihypertensives that are safe and effective in pediatric patients. They have relatively few adverse effects and are well tolerated by children. This article reviews CCAs as antihypertensives in the management of pediatric hypertension.

Coupling of human nicotinic acetylcholine receptors alpha 7 to calcium channels in GH3 cells.

The neuronal nicotinic acetylcholine receptor alpha7 (nAChR alpha7) may be involved in cognitive deficits in Schizophrenia and Alzheimer's disease. A fast pharmacological characterization of homomeric alpha7 receptors is mostly hampered by their low functional expression levels in heterologous expression systems. In the present study expression of homomeric nAChR alpha7 was achieved in GH3 rat pituitary cells. Alpha7 subunits were heterologously expressed as components of [125I]-labeled alpha-bungarotoxin binding nAChRs (Bmax: 1.2 pmol/mg protein). Function of the expressed alpha7 ion channels was assessed by patch-clamp recording and calcium imaging. While acetylcholine-induced currents desensitized within much less than 1 s, calcium-sensitive fluorescence transients peaked after 5-10 s and returned to background levels within 30 s only. The fluorescence signal was blocked by isradipine and removal of extracellular sodium indicated that in these cells opening of rapidly desensitizing alpha7 nAChR triggers calcium influx via voltage-gated, DHP-sensitive calcium channels. In this cellular system, agonists revealed the following rank order of potency: epibatidine>anatoxin A>AAR17779>ABT-594>DMPP>nicotine>GTS-21>cytisine>ABT-418>acetylcholine>choline>ABT-089. All of the signals were inhibited by the alpha7 antagonists alpha-bungarotoxin (pIC50: 7.4) and methyllycaconitine (pIC50: 7.8). Further, marketed antidepressants showed antagonistic activity with the following rank order of potency: fluoxetine>imipramine>paroxetine>sertraline. These data illustrate that coupling to voltage-gated calcium channels allows a rapid and reliable functional examination of nAChR alpha7.

Role of L-type calcium channel blocking in epidermal growth factor receptor-independent activation of extracellular signal regulated kinase 1/2.

OBJECTIVE: Vascular smooth muscle cell (VSMC) differentiation, growth and survival, key events in the development of cardiovascular diseases, are under the control of signaling enzymes including extracellular signal regulated kinase 1/2 (ERK 1/2), Akt and epidermal growth factor receptor (EGFR) activation. EGFR trans-activation is known to mediate thrombin- or angiotensin II (AII)-stimulated ERK 1/2 activation. However, our laboratory has demonstrated, in thrombin-stimulated VSMC, that the prevention of intracellular Ca2+ elevation ([Ca2+]i) by BAPTA-AM pretreatment unveiled EGFR-independent ERK 1/2 activation. Since calcium channel blockers (CCBs) also impair agonist-induced [Ca2+]i elevation, we investigated whether EGFR-independent ERK 1/2 activation could occur in VSMCs treated by CCBs such as amlodipine, isradipine and verapamil, and examined the possible role of Akt. METHODS: Cultured VSMCs were pretreated or not with CCBs and with various inhibitors of the signaling pathways under study, prior to stimulation by thrombin or AII, and the phosphorylation/activation status of EGFR, Akt and ERK 1/2 was determined by Western blotting using phospho-specific antibodies. RESULTS AND CONCLUSION: Unlike BAPTA, CCBs did not impair stimulus-induced EGFR trans-activation, hence ERK1/2 phosphorylation. However, when EGFR kinase was inhibited, CCBs and BAPTA dose-dependently protected stimulus-induced ERK1/2 phosphorylation. The effect of amlodipine could not be mimicked by its R+ enantiomer, which is devoid of CCB activity, suggesting that the effects of CCBs were accounted for by their L-type Ca2+ channel-blocking property. Altogether, our results indicated that in G-protein-coupled receptor (GPCR)-stimulated VSMCs, the prevention of [Ca2+]i elevation by CCBs unmasked an EGFR kinase-independent phosphorylation of ERK 1/2. Since EGFR kinase inhibitors are supposed to be efficient in the treatment of some cancers, such a mechanism might be clinically relevant in hypertensive patients with cancer.

Measurement of [³H]PN200-110 and [¹²5I]ω-conotoxin MVIIA binding.

Intracellular Ca(2+) ([Ca(2+)](i)) can rise primarily via release from intracellular storage sites (e.g., the endoplasmic reticulum) or via entry across the membrane down the steep concentration gradient. Ca(2+) can enter through two main classes of plasma membrane-located Ca(2+) channels: receptor operated and voltage sensitive. Voltage-sensitive Ca(2+) channels are involved in a wide and diverse array of physiological responses including neurotransmitter release. In addition, many guanine nucleotide protein (G) coupled receptors couple to voltage-sensitive Ca2(+) channels to reduce Ca(2+) influx.

Glycemia in newborns of hypertensive mothers according to maternal treatment

OBJETIVO: Avaliar o comportamento da glicemia em recém-nascidos (RN) de mães hipertensas conforme o tratamento materno. MÉTODOS: Estudo prospectivo, randomizado, incluindo 93 RN de mães tratadas com isradipina(n=39), atenolol (n=40) ou dieta - controle (n=14). Determinou-se a glicemia ao nascimento (mãe e RN, pela glicose oxidase) e na 1ª., 3ª., 6ª., 12ª. e 24ª. horas (RN, por fita reagente). A evolução da glicemia, em cada grupo, foi analisada (Teste de Friedman). Os grupos foram comparados, quanto às glicemias, em cada momento (Teste de Kruskall-Wallis) e foram ajustados modelos de regressão linear para as glicemias (variável independente = glicemia materna; variáveis dependentes = glicemias de cordão, 3ª. e 6ª. horas). RESULTADOS: Não houve diferença estatisticamente significante entre as glicemias médias dos 3 grupos, em qualquer uma das coletas. Houve correlação entre as glicemias materna e de cordão umbilical nos grupos isradipina (r =0,61; p<0,05) e controle (r =0,84; p<0,05); entre as glicemias materna e 3ª. e 6ª. horas, houve apenas no grupo controle (materna X 3ª.hora: r = 0,65; p<0,05; materna X 6a.hora: r =0,68; p<0,05). Não houve correlação em nenhum momento no grupo atenolol. Detectou-se hipoglicemia em 51,3% (Isradipina), 60% (Atenolol) e 35,7% (Controle), mais freqüentemente na 1ª. hora de vida, em todos os grupos. CONCLUSÕES: Os resultados sugerem efeito semelhante dos 3 tipos de terapêutica sobre a glicemia do RN. As análises de correlação sugerem que a isradipina possa ter efeitos sobre a glicemia somente após o nascimento (correlação apenas em cordão umbilical), enquanto o atenolol, possa atuar mais precocemente (não se correlacionou em nenhum momento). Também reforçam a necessidade de controle glicêmico desde a 1ª. hora de vida em RN de mães hipertensas, submetidas ou não a tratamento medicamentoso.