Implementation of cardiovascular secondary prevention guidelines in clinical practice: a nationwide survey in Italy.

AIMS: To report the implementation of cardiovascular secondary prevention guidelines following a cardiovascular event in Italy. METHODS AND RESULTS: Data were collected from 878 consecutive patients, who had suffered a cardiovascular event requiring hospitalisation in the preceding 12-24 months and who presented at 49 outpatient clinics across Italy. Cardiovascular risk markers were assessed through clinical examination, interview and reviewing of patients' charts; in addition, we collected information on changes in prevalence of selected risk factors that occurred since the time of index event. At the time of evaluation, increased body mass index (BMI) was observed in 35% of patients, with 20% being obese; 26% had diabetes and 21% uncontrolled hypertension. Although 91% of patients were on statins, no measurement of low-density lipoprotein (LDL)-cholesterol was available in the previous 6 months in 27% of patients and 16% had no knowledge of any lipid parameter in the same period. In the remaining patients, LDL was <100 mg dl(-1) in 57% and <70 mg dl(-1) in 20% of them. From the time of index event to interview, prevalence of uncontrolled hypertension remained stable, from 24% to 21% of patients; according to the patients' self-reporting, smoking had declined from 32% to 13% of patients and physical inactivity from 43% to 33% of patients. CONCLUSIONS: This survey shows, in a large national cohort, a suboptimal implementation of lifestyle changes and inadequate lipid control in patients at high cardiovascular risk after a cardiovascular event. Reinforcement of patients and physicians, implementation and adherence to guidelines is needed to reduce the burden of cardiovascular disease.

Regulation of c-myc expression by PDGF through Rho GTPases.

Src family protein-tyrosine kinases have a central role in several biological functions, including cell adhesion and spreading, chemotaxis, cell cycle progression, differentiation and apoptosis. Surprisingly, these kinases also participate in mitogenic signalling by receptors that themselves exhibit an intrinsic protein-tyrosine kinase activity, including those for platelet-derived growth factor (PDGF), epidermal growth factor and colony-stimulating factor-1. Indeed, Src kinases are strictly required for the nuclear expression of the c-myc proto-oncogene and thus for DNA synthesis in response to PDGF. However, the nature of the signalling pathways by which Src kinases participate in the induction of c-myc expression by tyrosine kinase receptors is still unknown. Here we show that PDGF enhances c-myc expression and stimulates the c-myc promoter in a Src-dependent manner, and that neither Ras nor the mitogen-activated protein kinase pathway mediate these effects. In contrast, we present evidence that PDGF stimulates Vav2 through Src, thereby initiating the activation of a Rac-dependent pathway that controls the expression of the c-myc proto-oncogene.

Activation of cAMP-PKA signaling in vivo inhibits smooth muscle cell proliferation induced by vascular injury.

Injury of the arterial wall induces the formation of the neointima. This structure is generated by the growth of mitogenically activated smooth muscle cells of the arterial wall. The molecular mechanism underlying the formation of the neointima involves deregulated cell growth, primarily triggered by the injury of the arterial wall. The activated gene products transmitting the injury-induced mitogenic stimuli have been identified and inhibited by several means: transdominant negative expression vectors, antisense oligodeoxynucleotides, adenovirus-mediated gene transfer, antibodies and inactivating drugs. Results of our study show that local administration of 3',5'-cyclic AMP and phosphodiesterase-inhibitor drugs (aminophylline and amrinone) to rats markedly inhibits neointima formation after balloon injury in vivo and in smooth muscle cells in vitro. The growth inhibitory effect of aminophylline was completely reversed by the inhibition of cAMP-dependent protein kinase A (PKA). These findings indicate an alternative approach to the treatment of diseases associated with injury-induced cell growth of the arterial wall, as stimulation of cAMP signaling is pharmacologically feasible in the clinical setting.

Effects of tissue factor induced by oxygen free radicals on coronary flow during reperfusion.

Tissue factor is a transmembrane protein that activates the extrinsic coagulation pathway by binding factor VII. Endothelial cells, being in contact with circulating blood, do not normally express tissue factor. Here we provide evidence that oxygen free radicals induce tissue factor messenger RNA transcription and expression of tissue factor procoagulant activity in endothelial cells in culture. Isolated, perfused rabbit hearts exposed to exogenous oxygen free radicals also showed a marked increase in tissue factor activity within the coronary circulation. Furthermore, in ex vivo and in vivo hearts subjected to ischemia and reperfusion, a condition associated with a production of oxygen free radicals in large amounts, a marked increase in tissue factor activity occurred. This phenomenon could be abolished by oxygen radical scavengers. This increase in tissue factor activity during postischemic reperfusion was accompanied by a significant decrease in coronary flow, suggesting that increase in tissue factor activity with the consequent activation of the coagulation cascade might impair coronary flow during reperfusion and possibly contribute to the occurrence of reperfusion injury.

Cardiac resynchronisation therapy response predicts occurrence of atrial fibrillation in non-ischaemic dilated cardiomyopathy.

AIM: The aim of this study was to determine whether or not cardiac resynchronization therapy (CRT) has a favourable effect on the incidence of new-onset atrial fibrillation (AF) in a homogeneous population of patients with non-ischaemic idiopathic-dilated cardiomyopathy and severe heart failure. METHODS: We designed a single-centre prospective study and enrolled 58 patients AF naïve when received CRT. After 1 year of follow-up our population was subdivided into responders (72.4%) and non-responders (27.6%), so as to compare the incidence of AF after 1, 2 and 3 years of follow-up in these two groups. RESULTS: Already after 1 year, there was a significant (p < 0.05) difference in new-onset AF in non-responder patients with respect to responders (18.2% vs. 3.3%). These data were confirmed at 2 years (33.3% vs. 12.2%) and 3 years (50.0% vs. 15.0%) follow-up. In particular, 3 years after device implantation non-responders had an increased risk to develop new-onset AF (OR = 5.67). CONCLUSIONS: This is the first study analysing long-term effects of CRT in a homogeneous population of patients with non-ischaemic dilated cardiomyopathy, indicating the favourable role of this non-pharmacological therapy on the prevention of AF.

Coronary flow reserve evaluation: basics, techniques and clinical applications.

Coronary flow reserve is a useful physiologic parameter providing information on coronary stenoses severity. To date, the gold standard to evaluate coronary flow reserve consists of fractional flow reserve (FFR) measurement, assessed with a pressure-wire. The FFR has a high lesion specificity, due to insensitivity to patient hemodynamic status and to coronary microvascular resistance; it shows low inter- and intraindividual variability and a well-defined, bound cut-off range values (0.75-0.80). Several reports confirmed that FFR has high reproducibility and feasibility in patients with either single- or multi-vessel coronary artery disease, or with both stable and instable coronary artery disease and that is significantly associated with patient outcome. More recently, the FFR has been used as a sensitive marker of successful percutaneous coronary intervention, since postprocedural FFR value strongly predicts patients event-free survival rate after angioplasty. Moreover, it has been demonstrated that abnormal FFR ratios can be also associated with diffused atherosclerotic coronary artery disease in the absence of unique angiographically detectable stenoses requiring revascularization. There are strong evidences supporting that the FFR provides crucial functional information that could be related with morphological endovascular ultrasound findings, with the possibility to achieve same information in a cheaper, easier and more available manner. This review will focus on the current available literature regarding coronary flow reserve quantification and its clinical validation, suggesting and highlighting its current and future clinical applications.

The prognostic impact of general and abdominal obesity in peripheral arterial disease.

OBJECTIVE: Obesity is an independent cardiovascular risk factor, but its prognostic role in patients with peripheral arterial disease (PAD) is not well defined. Accordingly, we assessed the impact of body mass index (BMI) and waist circumference (WC) on cardiovascular risk in a homogeneous cohort of PAD patients. METHODS: BMI and WC were measured in 190 consecutive PAD patients with ABI <0.90, referred to our university hospital for intermittent claudication. The occurrence of cardiac, cerebrovascular and peripheral events was prospectively assessed. The ability to classify risk was determined by calculating the hazard ratios (HRs) and c-statistics. RESULTS: During a median follow-up of 31.5 months, 63 patients (33.2%) had a cardiovascular event. Considered as continuous variables, both adiposity indices were significantly associated with increased cardiovascular risk, even after adjustment for possible confounding factors (HR=1.08, 95% CI 1.01-1.15, P=0.045 for BMI and HR=1.04, 95% CI 1.01-1.07, P=0.004 for WC). When BMI and WC were included together in a fully adjusted Cox model, the significant association between BMI and cardiovascular risk disappeared (HR=0.98, 95% CI 0.88-1.10, P=0.772), whereas WC remained significantly associated with a worse outcome (HR=1.04, 95% CI 1.01-1.08, P=0.033). The better discriminative ability of WC vs BMI was confirmed by the c-statistic, which was significantly higher for WC (0.63, 95% CI 0.56-0.70) than for BMI (0.56, 95% CI 0.51-0.63, P=0.038). CONCLUSIONS: Abdominal obesity and, to a lesser degree, general obesity worsen the prognosis of PAD patients independently of possible confounding factors. Weight reduction should be integrated in the active management of these patients.

Metabolic syndrome and cardiovascular risk prediction in peripheral arterial disease.

BACKGROUND AND AIMS: Metabolic syndrome (MetS) was reported to be associated with increased cardiovascular risk in various settings, however its prognostic impact in peripheral arterial disease (PAD) is scanty. METHODS AND RESULTS: We prospectively studied 173 patients with intermittent claudication and ankle/brachial index (ABI)<0.90, in whom MetS was defined using the criteria of both the revised version of the Adults Treatment Panel III (rATP III) and the International Diabetes Federation (IDF). Of these patients, 52.6% met the rATP III and 54.9% the IDF criteria for MetS. During a median follow-up of 31 months, 54 cardiovascular events occurred. Kaplan-Meier curves showed a greater incidence of ischemic events in patients with MetS than in those without. However, adjusted Cox analyses revealed that only IDF-MetS was independently associated with increased cardiovascular risk (HR=1.91, 95% CI 1.03-3.51, p=0.038). Kaplan-Meier curves for the four groups of patients delineated according to the bootstrapped ABI cut-off value (0.73) and the presence or absence of IDF-MetS revealed that the syndrome improved the predictive power of ABI alone. Actually, among patients with an ABI≤0.73, those with IDF-MetS had a higher cardiovascular risk than those without the syndrome (HR=2.55, 95% CI 1.22-5.12, p=0.012). This was confirmed by c-statistic, which was 0.56 for ABI alone and increased to 0.65 (p=0.046) when IDF-Mets was added to the pressure index. CONCLUSION: In PAD, IDF-MetS, but not rATP III-MetS, is associated with an increased risk of cardiovascular events. Furthermore, IDF-MetS adds to the prognostic value of ABI, currently the most powerful prognostic indicator in PAD.

Coronary stenting early before non-cardiac surgery: is the endothelial progenitor cell capturing coronary stent a solution?

The authors report, for the first time, immediate and mid-term outcome of early antiplatelet therapy discontinuation followed by uneventful non-cardiac surgery and endovascular aortic repair, few days after successful deployment of an endothelial progenitor cell capturing coronary stent, in three consecutive patients.

Relationship between insulin-like growth factor-1 system and exercise tolerance in patients with intermittent claudication.

AIM: Insulin-like growth factor-1 (IGF-1) plays an important role in exercise physiology. We aimed the present study at assessing whether IGF-1 system and its changes with exercise are related to walking capacity in intermittent claudication (IC). METHODS: In 45 IC patients, blood samples for the measurement of IGF-1, IGF binding protein-3 (IGFBP-3), and acid labile subunit (ALS) were taken at rest and immediately after a treadmill exercise performed until initial claudication distance (ICD), i.e. until the occurrence of claudication pain in the affected limb. Control group consisted of 45 age- and sex-matched subjects without previous myocardial infarction or stroke. RESULTS: When IC patients were divided into two groups according to ICD value, ANOVA showed significant group differences for IGFBP-3 and ALS. Indeed, resting levels of IGFBP-3 were 3537+/-109 microg/L in controls, moderately lower (3399+/-204 microg/L) in IC patients with ICD >or= median, and markedly lower (2580+/-196 microg/L) in those with ICD

Oxygen radicals inhibit human plasma acetylhydrolase, the enzyme that catabolizes platelet-activating factor.

Platelet-activating factor (PAF) can exert profound inflammatory effects at very low concentrations. In plasma, PAF is hydrolyzed to lyso-PAF by acetylhydrolase, an enzyme that circulates bound to LDL. Previous studies suggest that oxygen radicals may act synergistically with PAF to potentiate tissue injury. However, mechanisms underlying this interaction have not been elucidated. In this study we investigated whether oxygen radicals may inactivate PAF acetylhydrolase. PAF acetylhydrolase activity was measured in human plasma and purified LDL before and after exposure to radicals (10-20 nmol/min per ml) generated by xanthine/xanthine oxidase. Oxygen radicals induced > 50% loss of PAF acetylhydrolase activity within 60 s and almost complete inactivation by 10 min. This phenomenon was irreversible and independent of oxidative modification of LDL. Inactivation occurred without changes in the affinity constant of the enzyme (Km was 17.9 microM under control conditions and 15.1 microM after exposure to oxygen radicals). Inactivation was prevented by the scavengers superoxide dismutase or dimethylthiourea or by the iron chelator deferoxamine. Thus, superoxide-mediated, iron-catalyzed formation of hydroxyl radicals can rapidly and irreversibly inactivate PAF acetylhydrolase. Since concomitant production of PAF and oxygen radicals can occur in various forms of tissue injury, inactivation of acetylhydrolase might represent one mechanism by which oxygen radicals may potentiate and prolong the proinflammatory effects of PAF.

Reduction by cobra venom factor of myocardial necrosis after coronary artery occlusion.

Components of the complement system are known to play an important role in the cytolytic process and in chemotaxis of leukocytes. Cobra venom factor specifically cleaves C3 activity via activation of the alternative (properdin) complement pathway. It does not act directly on C3. If C3 is involved in tissue necrosis after ischemic injury, cobra venom factor might reduce tissue damage after acute coronary occlusion. Accordingly, in 14 control dogs occlusion of the left anterior descending artery was carried out for 24 h. Epicardial electrograms were recorded 15 min after occlusion, and 24 h later transmural specimens for creatine phosphokinase activity (CPK) and for histological analysis were obtained from the same sites. In another 14 experimental dogs, 20 U/kg cobra venom factor was given intravenously 30 min after occlusion. Serum complement levels fell within 2-4 h to <20% of normal. In the control dogs, the relationship between ST-segment elevation and CPK activity 24 h later was: log CPK = -0.06 ST + 1.48 (n = 111 specimens, 14 dogs, r = 0.77). In the experimental dogs, log CPK = -0.024 ST + 1.46 (n = 111 specimens, 14 dogs, r = 0.60), showing significantly different slopes (P < 0.001), i.e., less CPK depression for any level of ST-segment elevation. Histologically, 69 of 71 sites (97%) with ST-segment elevation exceeding 2 mV in the control dogs showed signs of necrosis 24 h later, whereas in the experimental group only 43 of 79 sites (54%) with abnormal ST-segment elevations showed signs of necrosis (P < 0.0005). At the same time, it was shown that the administration of cobra venom factor did not alter cardiac performance, collateral blood flow to the ischemic myocardium or the clotting system, but infiltration of polymorphonuclear leukocytes into the myocardium was decreased. It is concluded that cobra venom factor, by reducing the amount of C3 and C5 substrate available for chemotactic factor generation, or other as yet undefined mechanisms, protects the ischemic myocardium from undergoing necrosis, as judged by histology and local CPK activity. Hence, a new approach to limiting the extent of myocardial infarcts after experimental coronary occlusion, based upon inhibition of complement-dependent inflammatory processes, is demonstrated.

Oxygen radicals generated at reflow induce peroxidation of membrane lipids in reperfused hearts.

To test whether generation of oxygen radicals during postischemic reperfusion might promote peroxidation of cardiac membrane lipids, four groups of Langendorff-perfused rabbit hearts were processed at the end of (a) control perfusion, (b) 30 min of total global ischemia at 37 degrees C without reperfusion, (c) 30 min of ischemia followed by reperfusion with standard perfusate, (d) 30 min of ischemia followed by reperfusion with the oxygen radical scavenger human recombinant superoxide dismutase (h-SOD). The left ventricle was homogenized and tissue content of malonyldialdehyde (MDA), an end product of lipid peroxidation, was measured on the whole homogenate as well as on various subcellular fractions. Reperfusion was accompanied by a significant increase in MDA content of the whole homogenate and of the fraction enriched in mitochondria and lysosomes. This phenomenon was not observed in hearts subjected to ischemia but not reperfused, and was similarly absent in those hearts which received h-SOD at reflow. Reperfused hearts also had significantly greater levels of conjugated dienes (another marker of lipid peroxidation) in the mitochondrial-lysosomal fraction. Again, this phenomenon did not occur in ischemic hearts or in reperfused hearts treated with h-SOD. Unlike the effect on tissue MDA and conjugated dienes, reperfusion did not significantly stimulate release of MDA in the cardiac effluent. Treatment with h-SOD was also associated with significant improvement in the recovery of cardiac function. In conclusion, these data directly demonstrate that postischemic reperfusion results in enhanced lipid peroxidation of cardiac membranes, which can be blocked by h-SOD, and therefore is most likely secondary to oxygen radical generation at reflow.

Multiple mitogen-activated protein kinase signaling pathways connect the cot oncoprotein to the c-jun promoter and to cellular transformation.

The serine/threonine kinase Cot is a member of the mitogen-activated protein kinase (MAPK) kinase kinase family implicated in cellular transformation. Enhanced expression of this protein has been shown to activate both the MAPK and the c-Jun N-terminal kinase (JNK) pathways and to stimulate the nuclear factor of activated T cells and NF-kappaB-dependent transcription. However, the nature of the normal functions of the Cot protein and the molecular mechanisms responsible for its oncogenic potential are still largely unknown. Here, we show that overexpression of the cot proto-oncogene is sufficient to stimulate the expression of c-jun and that, in turn, the activity of c-Jun is required for Cot-induced transformation. These observations prompted us to explore the molecular events by which Cot regulates c-jun expression. We found that Cot potently stimulates the activity of the c-jun promoter utilizing JNK-dependent and -independent pathways, the latter involving two novel members of the MAPK family, p38gamma (ERK6) and ERK5. Molecularly, this activity was found to be dependent on the ability of Cot to activate, in vivo, members of each class of the MAPK kinase superfamily, including MEK, SEK, MKK6, and MEK5. Furthermore, the use of dominant interfering molecules revealed that Cot requires JNK, p38s, and ERK5 to stimulate the c-jun promoter fully and to induce neoplastic transformation. These findings indicate that Cot represents the first example of a serine/threonine kinase acting simultaneously on all known MAPK cascades. Moreover, these observations strongly suggest that the transforming ability of Cot results from the coordinated activation of these pathways, which ultimately converge on the regulation of the expression and activity of the product of the c-jun proto-oncogene.

A network of mitogen-activated protein kinases links G protein-coupled receptors to the c-jun promoter: a role for c-Jun NH2-terminal kinase, p38s, and extracellular signal-regulated kinase 5.

The expression of the c-jun proto-oncogene is rapidly induced in response to mitogens acting on a large variety of cell surface receptors. The resulting functional activity of c-Jun proteins appears to be critical for cell proliferation. Recently, we have shown that a large family of G protein-coupled receptors (GPCRs), represented by the m1 muscarinic receptor, can initiate intracellular signaling cascades that result in the activation of mitogen-activated protein kinases (MAPK) and c-Jun NH2-terminal kinases (JNK) and that the activation of JNK but not of MAPK correlated with a remarkable increase in the expression of c-jun mRNA. Subsequently, however, we obtained evidence that GPCRs can potently stimulate the activity of the c-jun promoter through MEF2 transcription factors, which do not act downstream from JNK. In view of these observations, we set out to investigate further the nature of the signaling pathway linking GPCRs to the c-jun promoter. Utilizing NIH 3T3 cells, we found that GPCRs can activate the c-jun promoter in a JNK-independent manner. Additionally, we demonstrated that these GPCRs can elevate the activity of novel members of the MAPK family, including ERK5, p38alpha, p38gamma, and p38delta, and that the activation of certain kinases acting downstream from MEK5 (ERK5) and MKK6 (p38alpha and p38gamma) is necessary to fully activate the c-jun promoter. Moreover, in addition to JNK, ERK5, p38alpha, and p38gamma were found to stimulate the c-jun promoter by acting on distinct responsive elements. Taken together, these results suggest that the pathway linking GPCRs to the c-jun promoter involves the integration of numerous signals transduced by a highly complex network of MAPK, rather than resulting from the stimulation of a single linear protein kinase cascade. Furthermore, our findings suggest that each signaling pathway affects one or more regulatory elements on the c-jun promoter and that the transcriptional response most likely results from the temporal integration of each of these biochemical routes.

Nicotine induces tissue factor expression in cultured endothelial and smooth muscle cells.

BACKGROUND AND OBJECTIVES: Cigarette smoking is associated with an increased risk to develop myocardial infarction and ischemic stroke. However, the mechanisms responsible for these effects are still poorly understood. AIM: To investigate whether nicotine, the major component of cigarette smoking, and its main metabolite, cotinine, might induce a pro-thrombotic state via stimulation of tissue factor (TF) expression in two cell population widely represented in the arterial wall such as endothelial cells (ECs), and smooth muscle cells (SMCs). METHODS AND RESULTS: Incubation of ECs and SMCs with nicotine and cotinine induced TF expression in both cell types in a dose-dependent fashion, exerting its effect at the transcriptional level, as demonstrated by semiquantitative and by real-time PCR. Nicotine- and cotinine-induced TF expression was mediated by the activation of the transcription factor, nuclear factor-kappa B (NF-kappaB), as demonstrated by electrophoretic mobility shift assay and by the suppression of TF expression by the NF-kappaB inhibitor, pyrrolidine dithio carbamate ammonium. CONCLUSIONS: These data indicate that nicotine and cotinine exert direct effects on ECs and SMCs, shifting them toward a pro-thrombotic state via induction of TF expression. These effects on cells of the vessel wall might explain, at least in part, the deleterious cardiovascular consequences of cigarette smoking.

Neopterin induces pro-atherothrombotic phenotype in human coronary endothelial cells.

BACKGROUND: Inflammation plays a pivotal role in atherothrombosis. Recent data indicate that serum levels of neopterin, a marker of inflammation and immune modulator secreted by monocytes/macrophages, are elevated in patients with acute coronary syndromes and seem to be a prognostic marker for major cardiovascular events. The aim of the present study was to determine whether neopterin might affect the thrombotic and atherosclerotic characteristics of human coronary artery endothelial cells (HCAECs). METHODS AND RESULTS: In HCAECs, neopterin induced TF-mRNA transcription as demonstrated by real time polymerase chain reaction and expression of functionally active tissue factor (TF) as demonstrated by procoagulant activity assay, and of cellular adhesion molecules (CAMs) as demonstrated by FACS analysis, in a dose-dependent fashion. These neopterin effects were prevented by lovastatin, a HMG-CoA reductase inhibitor. Neopterin-induced TF and CAMs expression was mediated by oxygen free radicals through the activation of the transcription factor, nuclear factor-kappa B (NF-kappaB), as demonstrated by electrophoretic mobility shift assay and by suppression of CAMs and TF expression by superoxide dismutase and by NF-kappaB inhibitor, pyrrolidine-dithio-carbamate ammonium. CONCLUSIONS: These data indicate that neopterin exerts direct effects on HCAECs by promoting CAMs and TF expression and support the hypothesis that neopterin, besides representing a marker of inflammation, might be an effector molecule able to induce a pro-atherothrombotic phenotype in cells of the coronary circulation.

Membrane-bound protein kinase A inhibits smooth muscle cell proliferation in vitro and in vivo by amplifying cAMP-protein kinase A signals.

cAMP-dependent protein kinase is anchored to discrete cellular compartments by a family of proteins, the A-kinase anchor proteins (AKAPs). We have investigated in vivo and in vitro the biological effects of the expression of a prototypic member of the family, AKAP75, on smooth muscle cells. In vitro expression of AKAP75 in smooth muscle cells stimulated cAMP-induced transcription, increased the levels of the cyclin-dependent kinase-2 inhibitor p27(kip1), and reduced cell proliferation. In vivo expression of exogenous AKAP75 in common carotid arteries, subjected to balloon injury, significantly increased the levels of p27(kip1) and inhibited neointimal hyperplasia. Both the effects in smooth muscle cells in vitro and in carotid arteries in vivo were specifically dependent on the amplification of cAMP-dependent protein kinase (PKA) signals by membrane-bound PKA, as indicated by selective loss of the AKAP75 biological effects in mutants defective in the PKA anchor domain or by suppression of AKAP effects by the PKA-specific protein kinase inhibitor. These data indicate that AKAP proteins selectively amplify cAMP-PKA signaling in vitro and in vivo and suggest a possible target for the inhibition of the neointimal hyperplasia after vascular injury.