Entry Blockers Research Articles

Role of Elevated Heart Rate in the Development of Cardiovascular Disease in Hypertension

That elevated heart rate (HR) is a risk factor for cardiovascular morbidity and mortality in healthy people as well as in patients with cardiac diseases is supported by numerous epidemiological association studies.1–4 Increased HR has been recognized as a negative prognostic factor independent of many other clinical parameters that can influence the HR, including physical activity scores, left ventricular function, or use of β-blockers. Thus, HR appears to satisfy all epidemiological criteria for being considered as a true risk factor, and its predictive value for cardiovascular disease appeared to be as strong as that of most important cardiovascular risk factors. This is particularly true for the results obtained in hypertensive patients. Elevated HR is a common feature among hypertensive individuals.1 Among the young hypertensive subjects participating in the HARVEST study, >15% had a baseline resting HR ≥85 bpm and 27% had a HR ≥80 bpm.5 According to the Tensiopulse study, which evaluated 38 145 patients cared for by 2000 general practitioners all across Italy, >30% of the hypertensive patients had a resting HR ≥80 bpm.6 In a large French population, untreated hypertensive subjects had approximately a 6-bpm faster HR than normotensive individuals.7 Elevated HR is frequently associated with high blood pressure (BP) and metabolic disturbances and increases the risk of new onset hypertension and diabetes.1 Many experimental data obtained both in animals and in human beings support the importance of HR as a true risk factor for atherosclerosis and cardiovascular disease, providing convincing evidence for this pathogenetic mechanism.1–3 The pathogenetic connection between HR and cardiovascular disease has been discussed in several reports1–3,8,9 and is beyond the scope of this review. ### High HR as a Precursor of Hypertension, Obesity, and Diabetes Numerous studies have demonstrated that tachycardia is frequently associated with hypertension in …

Preliminary Finding on a New Calcium Channel Entry Blocker Chemotype: 5,6-Diamino-4-hydroxy-2-mercaptopyrimidine Derivatives

We report the preliminary in vitro characterization of a series of pyrimidines as a new chemotype that modulates cardiovascular parameters and relaxes ileum smooth muscle according to classical calcium entry blockers. Tested compounds showed an interesting negative inotropic selectivity. In patch-clamp experiments they block L- over T-type calcium currents. Two requisites seem essential for the activity: lipophilic substituents in positions 2 and 5 of the pyrimidine ring and the acetamidic function in position 6.

Effects of different agents on the contractile response elicited by extracellular calcium after depletion of internal calcium stores in rat isolated aorta.

Noradrenaline, 1 microM, induced a sustained contractile response in rat isolated aorta in the presence and in the absence of extracellular Ca2+. After depleting the noradrenaline-sensitive intracellular Ca2+ stores, an increase in the basal tone of the aorta was observed during the incubation period in the presence of Ca2+ and in the absence of the agonist. We have tested the possible pathways through which Ca2+ enters the cell to refill the previously depleted Ca2+ pools, a process that is accompanied by an increase in tension. The magnitude of this increase does not depend on the presence of Mg2+ in the extracellular medium nor on the temperature, suggesting that it is mediated by an event that does not depend on intracellular energy or Ca2+, Mg(2+)-ATPase. It is inhibited in a concentration-dependent manner by an unspecific relaxing compound, caffeine, and an organic Ca2+ entry blocker, verapamil, but not by an inorganic Ca2+ entry blocker, lanthanum. Caffeine (10 mM) and verapamil (10(-5) M) completely inhibited the increase in the resting tone, but only verapamil abolished the refilling of the noradrenaline-sensitive Ca2+ pools, indicating that the extracellular Ca2+ enters the cell through voltage-operated Ca2+ channels. Caffeine inhibited the increase in the resting tone without blocking the refilling process of the stores at 37 degrees C, but at 25 degrees C a partial inhibition of the repletion of internal Ca2+ pools was observed. These results confirm previous work that showed a temperature-dependent activity of caffeine.

Influence of Calcium Entry Blockers and Calmodulin Inhibitors on 5-Hydroxytryptamine-, Potassium- and Calcium-induced Contractions in Human Umbilical Artery In-vitro

The effects of calcium (Ca2+) withdrawal, Ca2+ entry blockers and calmodulin inhibitors on the contractile responses to 5-hydroxytryptamine (5-HT), K+ and CaCl2 have been studied in human isolated umbilical artery. Following Ca2+ withdrawal from the medium (30 min), both 5-HT- and K(+)-induced contractions were virtually abolished. Ca2+ entry blockers (nifedipine, verapamil, diltiazem and cinnarizine) were significantly more effective in inhibiting 5-HT- than K(+)-induced contractions. In relation to calmodulin inhibitors, trifluoperazine inhibited all types of contractions, whereas W-7 (N-6-aminohexyl-5-chloro-1-naphthalene sulphonamide) only inhibited 5-HT- and CaCl2-induced contractions. All drugs inhibited CaCl2-induced contractions in a non-competitive manner. These findings indicate that the mechanisms by which these drugs exert their inhibitory effects on human umbilical artery are markedly different from those reported in other vascular beds.

Effect of verapamil and diltiazem on isolated gastro-oesophageal sphincter of the rat.

The effect of verapamil and diltiazem on the contraction induced by agonists on the rat lower oesophageal sphincter in-vitro has been studied. Both calcium entry blockers inhibited the contractile response to acetylcholine, carbachol and KCl. The potency of the inhibitory action was diltiazem greater than verapamil. The results give substance to the use of calcium entry blockers in the treatment of oesophageal spasm.

Tetrandrine and isotetrandrine, two bisbenzyltetrahydroisoquinoline alkaloids from Menispermaceae, with rat uterine smooth muscle relaxant activity.

The effects of two bisbenzyltetrahydroisoquinoline alkaloids, 1S,1'S tetrandrine and its isomer 1R,1'S isotetrandrine, were investigated in rat isolated uterus in order to identify the mechanism of relaxant action and to study the influence of the absolute configuration on the activity of these alkaloids. Both inhibited the uterine contraction induced by high K+, acetylcholine and oxytocin. In Ca(2+)-free medium, isotetrandrine relaxed the sustained contraction induced by oxytocin but tetrandrine did not. The relaxant effects of the alkaloids may be due to blockade of calcium influx through specific channels. Tetrandrine and isotetrandrine modify the calcium channel in a nonreversible manner whilst only isotetrandrine acts intracellularly. Tetrandrine shows a more specific relaxant activity as a calcium entry blocker.

Acute treatment with clonidine or calcium entry blockers on opioid withdrawal in guinea-pig ileum

Journal Article Acute treatment with clonidine or calcium entry blockers on opioid withdrawal in guinea-pig ileum Get access M J Alfaro, M J Alfaro Instituto de Farmacologia y Toxicología, Departamento de Farmacología, Facultad de Medicina, Universidad Complutense, Madrid, Spain Search for other works by this author on: Oxford Academic Google Scholar M I Colado, M I Colado Instituto de Farmacologia y Toxicología, Departamento de Farmacología, Facultad de Medicina, Universidad Complutense, Madrid, Spain Search for other works by this author on: Oxford Academic Google Scholar F Lopez, F Lopez Instituto de Farmacologia y Toxicología, Departamento de Farmacología, Facultad de Medicina, Universidad Complutense, Madrid, Spain Search for other works by this author on: Oxford Academic Google Scholar M I Martin M I Martin Instituto de Farmacologia y Toxicología, Departamento de Farmacología, Facultad de Medicina, Universidad Complutense, Madrid, Spain Correspondence to: M. I. Martin, Departamento de Farmacologia, Facultad de Medicina, Instituto de Farmacología y Toxicología, Universidad Complutense, 28040 Madrid, Spain. Search for other works by this author on: Oxford Academic Google Scholar Journal of Pharmacy and Pharmacology, Volume 42, Issue 10, October 1990, Pages 743–744, https://doi.org/10.1111/j.2042-7158.1990.tb06575.x Published: 12 April 2011 Article history Received: 23 May 1990 Published: 12 April 2011

Differential inhibition of alpha 2-adrenoceptor-mediated pressor responses by (+)- and (-)-verapamil in pithed rats.

The inhibitory effects of (+)- and (-)-verapamil on the hypertensive responses brought about by the alpha 2-adrenoceptor agonist B-HT 920 were investigated in pithed normotensive rats. (-)-Verapamil was found to be about 4 times more potent with respect to depressing alpha 2-pressor responses compared with (+)-verapamil. To rule out the effect of 'unspecific' vasodilatation after the administration of the stereoisomers of verapamil, vasopressin was continuously infused into the carotid artery of pithed rats in a separate series of experiments. In the course of this vasopressin infusion, new inhibitory activities of the stereoisomers of verapamil on alpha 2-adrenoceptor-mediated pressor responses were determined. Under these circumstances, the potency ratio of (-)- vs (+)-verapamil was about 7. With the aid of a radioligand binding assay using [3H]clonidine to identify alpha 2-adrenoceptors, low affinities were measured for the stereoisomers of verapamil. A Ki = 6170 nM for (-)-verapamil and a Ki = 41700 nM for (+)-verapamil were calculated. The results indicate that the interaction between alpha 2-adrenoceptor-mediated pressor responses and calcium entry blockers, such as verapamil, is a stereoselective event.

Investigation of the antimuscarinic and other actions of proadifen in-vitro.

The possibility that proadifen (SKF 525A) antagonizes endothelium-dependent relaxations to acetylcholine (ACh) in isolated blood vessel preparations via a muscarinic receptor blocking action has been investigated. In phenylephrine-contracted rat isolated aortic ring preparations (with endothelium), proadifen (10-100 microM) shifts ACh relaxant curves to the right without affecting the maximal response, yet endothelium-dependent relaxations to ATP are unaffected. At lower concentrations, proadifen (1-10 microM) antagonizes negative inotropic responses to ACh and ATP in guinea-pig left atria, antagonizes contractile responses to ACh and elevated [K+] in guinea-pig ileal preparations, displaces (-)-[3H]quinuclidinyl benzilate from muscarinic binding sites in membrane homogenates of guinea-pig ileal longitudinal muscle and reduces contractile responses to elevated [K+] in rat aortic ring preparations. It is concluded that proadifen may possess complex interactions with muscarinic receptors and Ca2+ entry blocking properties in concentrations 10-100 times lower than those reported to inhibit cytochrome P450-catalysed reactions.

Orai1-Mediated Calcium Entry Controls the Cytosolic Calcium Concentration and SR Calcium Loading in Quiescent Myotubes

In the absence of store depletion plasmalemmal Ca2+ permeability in resting muscle is very low and its contribution in the maintenance of Ca2+ homeostasis at rest has not been studied in detail. Junctophilin 1 knockout myotubes (JP1 KO) have a severe reduction in Store Operated Ca2+ Entry (SOCE), presumably caused by physical alteration of the sarcoplasmic reticulum (SR) and T tubule junction leading to disruption of the SR signal sent by Stim1 to activate Orai1. Using JP1 KO myotubes as a model, we assessed the contribution of Orai1 mediated Ca2+ entry pathway on the overall Ca2+ homeostasis at rest with no store depletion. JP1 KO myotubes have decreased Ca2+ entry, myoplasmic [Ca2+]rest and SR Ca2+ content compared to Wt myotubes and unlike Wt myotubes, are refractory to BTP2, a Ca2+ entry blocker. JP1 KO myotubes show down regulation of Orai1 and STIM1 proteins suggesting that this pathway may be important in the control of resting Ca2+ homeostasis. Wt myotubes stably transduced with Orai1(E190Q) had similar alterations in their resting Ca2+ homeostasis as JP1 KO myotubes and were also unresponsive to BTP2. JP1 KO cells show decreased expression of TRPC1 and 3 but over-express TRPC4 and 6, on the other hand the TRPCs expression profile in Orai1(E190Q) myotubes was comparable to Wt. These data suggest that an important fraction of the resting plasmalemmal Ca2+ permeability is mediated by the Orai1 pathway, which contributes to the control of [Ca2+]rest and resting Ca2+ stores and that this pathway is defective in JP1 KO myotubes.

R5X4 HIV-1 coreceptor use in primary target cells: implications for coreceptor entry blocking strategies

Entry coreceptor use by HIV-1 plays a pivotal role in viral transmission, pathogenesis and disease progression. In many HIV-1 infected individuals, there is an expansion in coreceptor use from CCR5 to include CXCR4, which is associated with accelerated disease progression. While targeting HIV-1 envelope interactions with coreceptor during viral entry is an appealing approach to combat the virus, the methods of determining coreceptor use and the changes in coreceptor use that can occur during disease progression are important factors that may complicate the use of therapies targeting this stage of HIV-1 replication. Indicator cells are typically used to determine coreceptor use by HIV-1 in vitro, but the coreceptors used on these cells can differ from those used on primary cell targets. V3 based genetic sequence algorithms are another method used to predict coreceptor use by HIV-1 strains. However, these algorithms were developed to predict coreceptor use in cell lines and not primary cells and, furthermore, are not highly accurate for some classes of viruses. This article focuses on R5X4 HIV-1, the earliest CXCR4-using variants, reviewing the pattern of coreceptor use on primary CD4+ lymphocytes and macrophages, the relationship between primary cell coreceptor use and the two principal approaches to coreceptor analysis (genetic prediction and indicator cell phenotyping), and the implications of primary cell coreceptor use by these strains for treatment with a new class of small molecule antagonists that inhibit CCR5-mediated entry. These are important questions to consider given the development of new CCR5 blocking therapies and the prognosis associated with CXCR4 use.

Identification of the minimal active sequence of an anti-influenza virus peptide.

The antiviral peptide, entry blocker (EB), inhibits influenza virus replication by preventing attachment to cells. Here, we identified the minimal and optimal EB sequence that retained antiviral activity with a 50% inhibitory concentration (IC(50)) and 50% effective concentration (EC(50)) similar to those of the full-length EB peptide and several truncated variants that possessed up to 10-fold lower IC(50)s. These data have implications for improving the antiviral efficacy of EB-derived peptides while decreasing production costs and easing synthesis.

Impaired Orai1-mediated Resting Ca2+ Entry Reduces the Cytosolic [Ca2+] and Sarcoplasmic Reticulum Ca2+ Loading in Quiescent Junctophilin 1 Knock-out Myotubes

In the absence of store depletion, plasmalemmal Ca(2+) permeability in resting muscle is very low, and its contribution in the maintenance of Ca(2+) homeostasis at rest has not been studied in detail. Junctophilin 1 knock-out myotubes (JP1 KO) have a severe reduction in store-operated Ca(2+) entry, presumably caused by physical alteration of the sarcoplasmic reticulum (SR) and T-tubule junction, leading to disruption of the SR signal sent by Stim1 to activate Orai1. Using JP1 KO myotubes as a model, we assessed the contribution of the Orai1-mediated Ca(2+) entry pathway on overall Ca(2+) homeostasis at rest with no store depletion. JP1 KO myotubes have decreased Ca(2+) entry, [Ca(2+)](rest), and intracellular Ca(2+) content compared with WT myotubes and unlike WT myotubes, are refractory to BTP2, a Ca(2+) entry blocker. JP1 KO myotubes show down-regulation of Orai1 and Stim1 proteins, suggesting that this pathway may be important in the control of resting Ca(2+) homeostasis. WT myotubes stably transduced with Orai1(E190Q) had similar alterations in their resting Ca(2+) homeostasis as JP1 KO myotubes and were also unresponsive to BTP2. JP1 KO cells show decreased expression of TRPC1 and -3 but overexpress TRPC4 and -6; on the other hand, the TRPC expression profile in Orai1(E190Q) myotubes was comparable with WT. These data suggest that an important fraction of resting plasmalemmal Ca(2+) permeability is mediated by the Orai1 pathway, which contributes to the control of [Ca(2+)](rest) and resting Ca(2+) stores and that this pathway is defective in JP1 KO myotubes.

Interrelationships between macro and microvascular structure and function

Macrovasculature and microvasculature are interrelated, and may influence each other. Microvascular structure is not only the site of vascular resistance but probably also the origin of most of the wave reflections generating increased central systolic blood pressure. Some index of large artery stiffness seems to be related with the media to lumen ratio of subcutaneous small resistance arteries of hypertensive patients. In addition, both microvascular structural alterations and changes in the mechanical properties of large arteries represent potent predictors of prognosis. In addition, drugs that may improve microvascular structure may also correct alterations in the mechanical properties of large arteries In fact, while β-blocking agents and diuretics have a negligible effect on microvascular structure, renin-angiotensin system antagonists and calcium entry blockers have favorable actions, improving also large artery mechanics and possibly reducing central wave reflections.

The Cardiovascular Nutrapharmacology of Resveratrol: Pharmacokinetics, Molecular Mechanisms and Therapeutic Potential

Red wine contains many compounds that may have therapeutic use, including resveratrol (3,4',5-trihydroxytrans-stilbene). Since resveratrol could be administered both in the diet and as a therapeutic agent, defining appropriate concentrations requires understanding of the pharmacokinetics. Resveratrol absorption is rapid but plasma concentrations are low as it is rapidly and efficiently converted into relatively hydrophilic phase-2 conjugates, and metabolites, which are then rapidly excreted via the urine and bile. Resveratrol is an effective antioxidant in vivo by increasing NO synthesis and also maintaining the reduced intracellular redox state via the thioredoxin system. Further, activation of sirtuins (one class of lysine deacetylases) may mediate the cardiovascular responses shown by resveratrol. Studies on animal models of human disease suggest that resveratrol has the potential to decrease cardiovascular symptoms in patients with myocardial infarction, arrhythmias, hypertension, cardiomyopathies, fibrosis, atherosclerosis, thrombosis and diabetes, but, as yet, human clinical trials are rare. Cardioprotection by resveratrol in rodent models may rely on mechanisms producing pharmacological preconditioning in the heart including reducing reactive oxygen species, improving vasorelaxation and angiogenesis, preventing inflammation and apoptosis, delaying atherosclerosis as well as decreasing cardiovascular remodelling. Interventional studies in humans need to be completed before resveratrol can be considered as a standard therapeutic agent. Therefore, future studies should focus on obtaining the level of evidence required to determine whether resveratrol can be added to the list of evidence-based therapies for cardiovascular diseases that includes renin-angiotensin system inhibitors, beta-adrenoceptor antagonists and calcium entry blockers.

Design, synthesis and pharmacological screening of hybrid molecules as antihypertensives

The synthesis and pharmacological profile of a series of hybrid compounds bearing the dihydropyrimidine moiety and substituted phenylthioureas joined via typical β-blocker aryloxypropanolamine group are described. Seven out of 10 new compounds tested proved to be endowed with negative inotropic and chronotropic effect as compared to Adrenaline on isolated perfused frog heart. Also ECG studies that were carried out on normotensive male rats showed that the most of the compounds exhibited significant reduction in Rmax value in the first 30 min although maintaining little change in heart rate, with hypotensive effect lasting for 1 h. We concluded that the most of the synthesized novel compounds exhibited hypotensive as well as antihypertensive effects which could be attributed to blockade of Ca2+ entry and β-adrenoreceptor blocking activities due to introduction of aryloxypropanolamine linked to N-1 substituted dihydropyrimidine moiety. Brady cardiac effects of compounds 5a–5d, 6c–6e resulting from Ca2+ entry and β-adrenoreceptor blocking attenuate the sympathetic activation-associated reflex tachycardia in the heart. We selected compound 5c as a promising lead for further detailed pharmacological and preclinical evaluation studies.

ChemInform Abstract: Synthesis and Preliminary Biological Evaluation of 4,6-Disubstituted 3-Cyanopyridin-2(1H)-ones, a New Class of Calcium Entry Blockers.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

A malignant hyperthermia-inducing mutation in RYR1 (R163C): alterations in Ca2+ entry, release, and retrograde signaling to the DHPR.

Bidirectional signaling between the sarcolemmal L-type Ca2+ channel (1,4-dihydropyridine receptor [DHPR]) and the sarcoplasmic reticulum (SR) Ca2+ release channel (type 1 ryanodine receptor [RYR1]) of skeletal muscle is essential for excitation–contraction coupling (ECC) and is a well-understood prototype of conformational coupling. Mutations in either channel alter coupling fidelity and with an added pharmacologic stimulus or stress can trigger malignant hyperthermia (MH). In this study, we measured the response of wild-type (WT), heterozygous (Het), or homozygous (Hom) RYR1-R163C knock-in mouse myotubes to maintained K+ depolarization. The new findings are: (a) For all three genotypes, Ca2+ transients decay during prolonged depolarization, and this decay is not a consequence of SR depletion or RYR1 inactivation. (b) The R163C mutation retards the decay rate with a rank order WT > Het > Hom. (c) The removal of external Ca2+ or the addition of Ca2+ entry blockers (nifedipine, SKF96365, and Ni2+) enhanced the rate of decay in all genotypes. (d) When Ca2+ entry is blocked, the decay rates are slower for Hom and Het than WT, indicating that the rate of inactivation of ECC is affected by the R163C mutation and is genotype dependent (WT > Het > Hom). (e) Reduced ECC inactivation in Het and Hom myotubes was shown directly using two identical K+ depolarizations separated by varying time intervals. These data suggest that conformational changes induced by the R163C MH mutation alter the retrograde signal that is sent from RYR1 to the DHPR, delaying the inactivation of the DHPR voltage sensor.

A Small-Molecule Oxocarbazate Inhibitor of Human Cathepsin L Blocks Severe Acute Respiratory Syndrome and Ebola Pseudotype Virus Infection into Human Embryonic Kidney 293T cells

A tetrahydroquinoline oxocarbazate (PubChem CID 23631927) was tested as an inhibitor of human cathepsin L (EC 3.4.22.15) and as an entry blocker of severe acute respiratory syndrome (SARS) coronavirus and Ebola pseudotype virus. In the cathepsin L inhibition assay, the oxocarbazate caused a time-dependent 17-fold drop in IC(50) from 6.9 nM (no preincubation) to 0.4 nM (4-h preincubation). Slowly reversible inhibition was demonstrated in a dilution assay. A transient kinetic analysis using a single-step competitive inhibition model provided rate constants of k(on) = 153,000 M(-1)s(-1) and k(off) = 4.40 x 10(-5) s(-1) (K(i) = 0.29 nM). The compound also displayed cathepsin L/B selectivity of >700-fold and was nontoxic to human aortic endothelial cells at 100 muM. The oxocarbazate and a related thiocarbazate (PubChem CID 16725315) were tested in a SARS coronavirus (CoV) and Ebola virus-pseudotype infection assay with the oxocarbazate but not the thiocarbazate, demonstrating activity in blocking both SARS-CoV (IC(50) = 273 +/- 49 nM) and Ebola virus (IC(50) = 193 +/- 39 nM) entry into human embryonic kidney 293T cells. To trace the intracellular action of the inhibitors with intracellular cathepsin L, the activity-based probe biotin-Lys-C5 alkyl linker-Tyr-Leu-epoxide (DCG-04) was used to label the active site of cysteine proteases in 293T lysates. The reduction in active cathepsin L in inhibitor-treated cells correlated well with the observed potency of inhibitors observed in the virus pseudotype infection assay. Overall, the oxocarbazate CID 23631927 was a subnanomolar, slow-binding, reversible inhibitor of human cathepsin L that blocked SARS-CoV and Ebola pseudotype virus entry in human cells.

Synergism between Ca2+ and Rho‐kinase signaling during pulmonary arterial vasoconstriction in chronic hypoxic newborn lamb

Pulmonary artery (PA) contractility is mediated in large part by increases in cytosolic Ca2+, which activates myosin light chain (MLC) kinase and in turn phosphorylates myosin light chain20 (MLC20). Rho‐kinase further enhances phosphorylation of MLC20 and contractility through inhibition of MLC phosphatase. We hypothesized that Ca2+ and Rho‐kinase signaling synergistically regulate pulmonary vascular tone in chronically hypoxic (CH) newborn lambs. This hypothesis was tested by performing wire myography on serotonin (5‐HT) stimulated PA rings isolated from 12 to 17 day old lambs maintained at high altitude (3801 m) for the final 100 days of gestation and after birth (CH). 5‐HT elicited dose‐dependent contractions were attenuated with various Ca2+ entry or Rho‐kinase blockers. Voltage dependent and independent Ca2+ entry was inhibited with 30 μM KB‐R7943 (KBR), 100 μM flufenamate (FFA), 30 μM SN‐6, or 10 μM nifedipine (NIF) in the absence or presence of 50 μM SKF‐96365 (SKF). Rho‐kinase was inhibited with 10 μM fasudil or Y27632. The potency order for the Ca2+ entry antagonists was KBR ≥ NIF+SKF ≫ NIF > FFA ≫ SN‐6, whileY27632 > fasudil. Fasudil substantially augmented the inhibitory action of the Ca2+ entry blockers. These findings support the rationale for treating pulmonary hypertension with medications that target both Ca2+ and Rho‐kinase pathways. NIH P01HD031226, R01HD003807 (LDL), R01HL95973 (AB)