Self-reported hypertension, dyslipidemia and hyperuricemia management by Italian Internal Medicine Units: a national survey of the FADOI Study Group in Cardiovascular Medicine

The aim of this study was to evaluate the management practices of internal medicine clinicians for patients with cardiovascular risk factors, with particular respect to treatment thresholds, medication choices and target goals. A sample of internists - representatives of Internal Medicine Units (IMUs) from all the regions in Italy - were identified by the cardiovascular medicine study group of the Italian Internal Medicine FADOI (Federazione delle Associazioni dei Dirigenti Ospedalieri Internisti) Society and invited to fill out a questionnaire about hypertension, dyslipidemia and hyperuricemia. From the 101 questionnaires collected, it was found that despite large heterogeneity between IMUs in terms of patient management and adherence to guidelines, internists were experts in the management of patients with multiple cardiovascular risk factors and associated comorbidities. We hope that these data prompt the internal medicine community to consider the value of producing shared, real-world guidelines on the management of cardiovascular disease.

In-hospital symptomatic venous thromboembolism and antithrombotic prophylaxis in Internal Medicine

Hospitalised medical patients are at increased risk of venous thromboembolism (VTE), but the incidence of hospitalisation-related VTE in unselected medical inpatients has not been extensively studied, and uncertainties remain about the optimal use of thromboprophylaxis in this setting. Aims of our prospective, observational study were to assess the prevalence of VTE and the incidence of symptomatic, hospitalisation-related events in a cohort of consecutive patients admitted to 27 Internal Medicine Departments, and to evaluate clinical factors associated with the use of thromboprophylaxis. Between March and September 2006, a total of 4,846 patients were included in the study. Symptomatic VTE with onset of symptoms later than 48 hours after admission (”hospital-acquired” events, primary study end-point) occurred in 26 patients (0.55٪), while the overall prevalence of VTE (including diagnosis prior to or at admission) was 3.65٪. During hospital stay antithrombotic prophylaxis was administered in 41.6٪ of patients, and in 58.7% of those for whom prophylaxis was recommended according to the 2004 Guidelines of the American College of Chest Physicians. The choice of administering thromboprophylaxis or not appeared qualitatively adherent to indications from randomised clinical trials and international guidelines, and bed rest was the strongest determinant of the use of prophylaxis. Data from our real-world study confirm that VTE is a relevant complication in patients admitted to Internal Medicine Departments, and recommended tromboprophylaxis is still under-used, in particular in some patients groups. Further efforts are needed to better define risk profile and to optimise prophylaxis in the heterogeneous setting of medical inpatients.

Risk factors for venous thromboembolism and prophylaxis in medical inpatients: data from the FADOI ‘‘GEMINI’’ study

Background: Though venous thromboembolism (VTE) frequently occurs in non-surgical setting, epidemiology and risk factors for VTE in unselected medical inpatients have not been extensively studied, and uncertainties remain about the prophylactic strategy in these patients. Materials and methods: In a prospective, observational, multicenter study we aimed to contemporarily assess the epidemiology of symptomatic VTE in consecutive patients hospitalized in Internal Medicine, to evaluate the impact of potential risk factors, and the attitude of internists towards thromboprophylaxis. A total of 4,846 patients were included, during the period March-September 2006. Results: Symptomatic VTE was registered in 177 (3.65%) patients; of these, 26 cases (0.55%) occurred with onset of symptoms > 48 hours after admission (‘‘hospital-acquired’’ events, primary study end-point). Previous VTE and bed resting were significantly associated with venous thromboembolism, while a trend for increased risk was documented in cancer patients. During hospital stay antithrombotic prophylaxis was globally administered in 41.6% of patients, and in 58.4% of those for which prophylaxis was recommended according to 2004 guidelines by the American College of Chest Physicians. The choice of administering tromboprophylaxis appeared qualitatively adherent to indications from randomized trials and international guidelines, and bed rest was the strongest determinant of the use of prophylaxis. Conclusions: Data from our real-world study confirm that VTE is a quite common finding in patients admitted to Internal Medicine departments, and recommended tromboprophylaxis is still underused, in particular in some patients groups. Further efforts are needed to better define the risk profile and to optimize prophylaxis in the heterogeneous setting of medical patients.

Incidence and predictors of venous thromboembolism in post-acute care patients. A prospective cohort study

Few studies have addressed the topic of venous thromboembolism (VTE) in patients hospitalised in rehabilitation facilities. This patient population is rapidly growing, and data aimed to better define VTE risk in this setting are needed. Primary aim of this prospective observational study was to evaluate the frequency of symptomatic, objectively confirmed VTE in a cohort of unselected consecutive patients admitted to rehabilitation facilities, after medical diseases or surgery. Further objectives were to assess overall mortality, to identify risk factors for VTE and mortality, and to assess the attitude of physicians towards thromboprophylaxis. A total of 3,039 patients were included in the study, and the median duration of hospitalisation was 26 days. Seventy-two patients (2.4%) had symptomatic VTE. The median time to VTE from admission to the long-term care unit was 13 days. According to multivariable analysis, previous VTE (hazard ratio 5.67, 95% confidence interval 3.30-9.77) and cancer (hazard ratio 2.26, 95% confidence interval 1.36-3.75) were significantly associated to the occurrence of VTE. Overall in-hospital mortality was 15.1%. Age over 75 years, male gender, disability, cancer, and the absence of thromboprophylaxis were significantly associated to an increased risk of death (multivariable analysis). In-hospital antithrombotic prophylaxis was administered to 75.1% of patients, and low-molecular-weight heparin was the most widely used agent. According to our study, patients admitted to rehabilitation facilities remain at substantially increased risk for VTE. Because this applies to the majority of these patients, there is a great need for clinical trials assessing optimal prophylactic strategies.

Extended prophylaxis of venous thromboembolism with fondaparinux in patients undergoing major orthopaedic surgery in Italy: a cost-effectiveness analysis

Enoxaparin is the most frequently used low-molecular weight heparin in the world, given in order to prevent venous thromboembolism (VTE) in patients undergoing major orthopaedic surgery (MOS). Fondaparinux is an effective and safe alternative. The aim of our study was to compare the cost-effectiveness of enoxaparin and fondaparinux in the extended thromboprophylaxis of patients undergoing MOS in Italy. A decision-tree model was developed: probabilities of symptomatic events were derived from the published trials; use of resources in Italy was evaluated by means of a questionnaire administered to a panel of experts. Only the direct costs of VTE (acute treatment of events and of complications) were considered. Cost units were derived from the current cost of drugs, and from the Italian National Healthcare tariffs in 2007. Incremental cost-effectiveness ratios were analysed at three time points: 30 days, 1 year and 5 years. The higher cost of fondaparinux was counterbalanced by reduced rates of early DVT, early PE and prophylaxis-related major bleeding. If compared with enoxaparin, after 30 days of extended prophylaxis, fondaparinux is associated with a savings of <euro> 48.83 per patient; at the end of the first year, the savings increased to <euro> 72.13, and after 5 years, the savings are <euro> 74.36. One-way sensitivity analysis shows that the results are robust to the variation in unit costs for VTE-related care, or in event rates for both treatments. In conclusion, our model shows that, when administered for extended prophylaxis of VTE following MOS, fondaparinux is more effective and cost saving than enoxaparin.

Residual thrombosis on ultrasonography to guide the duration of anticoagulation in patients with deep venous thrombosis: a randomized trial

BACKGROUND

The optimal duration of oral anticoagulant therapy in patients with deep venous thrombosis (DVT) of the lower extremities remains uncertain.

OBJECTIVE

To assess whether tailoring the duration of anticoagulation on the basis of the persistence of residual thrombi on ultrasonography reduces the rate of recurrent venous thromboembolism (VTE) compared with the administration of conventional fixed-duration treatment in adults with proximal DVT.

DESIGN

Parallel, randomized trial from 1999 to 2006. Trained physicians who assessed outcomes were blinded to patient assignment status, but patients and providers were not.

SETTING

9 university or hospital centers in Italy.

PATIENTS

538 consecutive outpatients with a first episode of acute proximal DVT at completion of an uneventful 3-month period of anticoagulation.

INTERVENTION

Patients were randomly assigned (stratified by center and secondary vs. unprovoked DVT by using a computer-generated list that was accessible only to a trial nurse) to fixed-duration anticoagulation (no further anticoagulation for secondary thrombosis and an extra 3 months for unprovoked thrombosis) or flexible-duration, ultrasonography-guided anticoagulation (no further anticoagulation in patients with recanalized veins and continued anticoagulation in all other patients for up to 9 months for secondary DVT and up to 21 months for unprovoked thrombosis). For the primary outcome assessment, 530 patients completed the trial.

MEASUREMENTS

The rate of confirmed recurrent VTE during 33 months of follow-up.

RESULTS

Overall, 46 (17.2%) of 268 patients allocated to fixed-duration anticoagulation and 32 (11.9%) of 270 patients allocated to flexible-duration anticoagulation developed recurrent VTE (adjusted hazard ratio [HR], 0.64 [95% CI, 0.39 to 0.99]). For patients with unprovoked DVT, the adjusted HR was 0.61 (CI, 0.36 to 1.02) and 0.81 (CI, 0.32 to 2.06) for those with secondary DVT. Major bleeding occurred in 2 (0.7%) patients in the fixed-duration group and 4 (1.5%) patients in the flexible-duration group (P = 0.67).

LIMITATIONS

The trial lacked a double-blind design. The sample size was not powered to detect differences in bleeding between groups and to detect effectiveness of the intervention in the subgroups of patients with unprovoked and secondary DVT. Patients with previous thromboembolism, permanent risk factors for thrombosis, and thrombophilic abnormalities other than factor V Leiden and prothrombin mutation were excluded.

CONCLUSION

Tailoring the duration of anticoagulation on the basis of ultrasonography findings reduces the rate of recurrent VTE in adults with proximal DVT.

PRIMARY FUNDING SOURCE

None.

In-hospital symptomatic venous thromboembolism and antithrombotic prophylaxis in Internal Medicine. Findings from a multicenter, prospective study

Hospitalised medical patients are at increased risk of venous thromboembolism (VTE), but the incidence of hospitalisation-related VTE in unselected medical inpatients has not been extensively studied, and uncertainties remain about the optimal use of thromboprophylaxis in this setting. Aims of our prospective, observational study were to assess the prevalence of VTE and the incidence of symptomatic, hospitalisation-related events in a cohort of consecutive patients admitted to 27 Internal Medicine Departments, and to evaluate clinical factors associated with the use of thromboprophylaxis. Between March and September 2006, a total of 4,846 patients were included in the study. Symptomatic VTE with onset of symptoms later than 48 hours after admission ("hospital-acquired" events, primary study end-point) occurred in 26 patients (0.55%), while the overall prevalence of VTE (including diagnosis prior to or at admission) was 3.65%. During hospital stay antithrombotic prophylaxis was administered in 41.6% of patients, and in 58.7% of those for whom prophylaxis was recommended according to the 2004 Guidelines of the American College of Chest Physicians. The choice of administering thromboprophylaxis or not appeared qualitatively adherent to indications from randomised clinical trials and international guidelines, and bed rest was the strongest determinant of the use of prophylaxis. Data from our real-world study confirm that VTE is a relevant complication in patients admitted to Internal Medicine Departments, and recommended tromboprophylaxis is still under-used, in particular in some patients groups. Further efforts are needed to better define risk profile and to optimise prophylaxis in the heterogeneous setting of medical inpatients.

Three months versus one year of oral anticoagulant therapy for idiopathic deep venous thrombosis. Warfarin Optimal Duration Italian Trial Investigators

BACKGROUND

In patients with idiopathic deep venous thrombosis, continuing anticoagulant therapy beyond three months is associated with a reduced incidence of recurrent thrombosis during the period of therapy. Whether this benefit persists after anticoagulant therapy is discontinued is controversial.

METHODS

Patients with a first episode of idiopathic proximal deep venous thrombosis who had completed three months of oral anticoagulant therapy (with warfarin, in 97 percent of the cases and acenocoumarol in 3 percent) were randomly assigned to the discontinuation of oral anticoagulants or to their continuation for nine additional months. The primary study outcome was recurrence of symptomatic, objectively confirmed venous thromboembolism during at least two years of follow-up.

RESULTS

The primary intention-to-treat analysis showed that of 134 patients assigned to continued oral anticoagulant therapy, 21 had a recurrence of venous thromboembolism (15.7 percent; average follow-up, 37.8 months), as compared with 21 of 133 patients assigned to the discontinuation of oral anticoagulant therapy (15.8 percent; average follow-up, 37.2 months), resulting in a relative risk of 0.99 (95 percent confidence interval, 0.57 to 1.73). During the initial nine months after randomization (after all patients received three months of therapy), 1 patient had a recurrence while receiving oral anticoagulant therapy (0.7 percent), as compared with 11 of the patients assigned to the discontinuation of oral anticoagulant therapy (8.3 percent; P=0.003). The incidence of recurrence after the discontinuation of treatment was 5.1 percent per patient-year in patients in whom oral anticoagulant therapy was discontinued after 3 months (95 percent confidence interval, 3.2 to 7.5 percent; average interval since discontinuation, 37.2 months) and 5.0 percent per patient-year in patients who received an additional 9 months of oral anticoagulant therapy (95 percent confidence interval, 3.1 to 7.8 percent; average interval since discontinuation, 29.4 months). None of the recurrences were fatal. Four patients had non-fatal major bleeding during the extended period of anticoagulant therapy (3.0 percent).

CONCLUSIONS

In patients with idiopathic deep venous thrombosis, the clinical benefit associated with extending the duration of anticoagulant therapy to one year is not maintained after the therapy is discontinued.

Neoadiuvant treatment with intravesical interleukin-2 for recurrent superficial transitional bladder carcinoma Ta-T1/G1-2

The aim of this study was to evaluate the direct action of IL-2 on recurrent superficial transitional bladder carcinoma and the effect on recurrence rate. 27 patients were submitted to neoadjuvant treatment by intra-vesical instillation of recombinant IL-2 and to transurethral resection. We did not observe any effect on neoplasms but the recurrence rate was less than the expected one. It is possible that treatment of bladder carcinoma with intra-vesical instillation of IL-2 may promote immuno-prophilaxis.

[Ultrasonographic, serologic, and clinical characteristics of a case of prostatic malacoplakia]

An additional case of malakoplakia of the prostate in described to highlight its clinical, echographic and serum features. It's a rarest disease especially when prostate is involved, but well known in world literature. This case is reported to describe more accurately its echographic patterns and also for growing up precision in linguistical expressions used by echographists. We hope to contribute in collecting data about an uncommon pathology. At last we discuss about differential diagnosis when biopsy is negative for neoplasia and how it's possible to end further biopsies.

Carotid endarterectomy without angiography: can clinical evaluation and duplex ultrasonographic scanning alone replace traditional arteriography for carotid surgery workup? A prospective study

BACKGROUND

The aim of this study was to determine whether clinical evaluation and duplex ultrasonography (DUS) alone can replace contrast cerebral arteriography (CA) for the detection of patients suitable for surgery at our institution.

METHODS

During an 18-month period, 100 patients underwent DUS and CA during evaluation for carotid endarterectomy (CEA). All patients were studied prospectively; in each case an initial decision for or against CEA on the basis of DUS evaluation of the internal carotid arteries (ICAs) was subsequently compared with the surgeon's final management plan after CA. Of the 200 ICAs evaluated, 113 were considered for CEA but 14 were excluded from the study because the patient could not be evaluated before and after CA. This left 99 ICAs (86 patients) available for comparative analysis.

RESULTS

The outcome of the 2 diagnostic modalities was perfectly consistent in 95.3% of the ICAs (kappa = 0.969). The clinical management decision was altered by the CA findings in only 2 cases (2%). Of the 99 ICAs considered suitable, 97 underwent CEA. No arteriographic complications occurred among the 100 patients undergoing CA. The perioperative stroke risk and mortality rates were 0%.

CONCLUSIONS

Ninety-eight percent of the ICAs considered for surgery would have received appropriate clinical treatment on the strength of the patients' neurologic history and the outcome of DUS alone. Our results indicate that DUS is sufficient to establish the need for surgery in symptomatic and asymptomatic patients being considered for CEA and can replace CA in most clinical circumstances.

D-dimer testing as an adjunct to ultrasonography in patients with clinically suspected deep vein thrombosis: prospective cohort study. The Multicentre Italian D-dimer Ultrasound Study Investigators Group

OBJECTIVE

To investigate the efficacy of using a rapid plasma D-dimer test as an adjunct to compression ultrasound for diagnosing clinically suspected deep vein thrombosis.

DESIGN

D-dimer concentrations were determined in all patients with a normal ultrasonogram at presentation. Repeat ultrasonography was performed 1 week later only in patients with abnormal D-dimer test results.

MAIN OUTCOME AND MEASURES

Patients with normal ultrasonograms were not treated with anticoagulants and were followed for 3 months for thromboembolic complications.

SETTING

University research and affiliated centres.

SUBJECTS

946 patients with clinically suspected deep vein thrombosis.

RESULTS

Ultrasonograms were abnormal at presentation in 260 (27.5%) patients. Of the remaining 686 patients tested for D-dimer, 88 (12.8%) had abnormal concentrations. During follow up venous thromboembolic complications occurred in one of the 598 patients who were not treated with anticoagulants and who had an initial normal ultrasonogram and D-dimer concentration, whereas thromboembolic complications occurred in two of the 83 untreated patients who had abnormal D-dimer concentrations but a normal repeat ultrasonogram. The cumulative incidence of venous thromboembolic complications during follow up was 0.4% (95% confidence interval 0% to 0.9%). The rapid plasma D-dimer test used as an adjunct to compression ultrasonography resulted in a reduction in the mean number of repeat ultrasound examinations and additional hospital visits from 0.7 to 0.1 per patient.

CONCLUSIONS

Testing for D-dimer as an adjunct to a normal baseline ultrasound examination decreased the number of subsequent ultrasound examinations considerably without any increased risk of venous thromboembolic complications in patients not receiving anticoagulants. The use of ultrasound and testing for D-dimer enabled treatment decisions to be made at the time of presentation in most patients.

Non-muscle myosin isoforms and cell heterogeneity in developing rabbit vascular smooth muscle

A panel of monoclonal antibodies specific for cytoskeletal and cytocontractile protein markers has been used to study the expression of vimentin, desmin and alpha-smooth muscle (SM) actin, as well as non-muscle (NM) and SM myosin isoforms, in developing rabbit aorta. Immunofluorescence experiments show that in the vascular smooth muscle cells (SMC): (1) vimentin and alpha-actin of SM-type are homogeneously expressed among SMC, since the early stage (day 19, in uterus) of development; (2) desmin is heterogeneously distributed throughout all the developmental stages examined (from day 19, foetal, to day 90, post-natal); and (3) myosin isoform content in pre- and post-natal vascular SM is different when analyzed by anti-SM myosin (SM-E7) and anti-NM myosin (NM-F6, NM-A9 and NM-G2) antibodies. SM myosin in vascular SM is present as early as day 19 in uterus, being especially evident in the region facing the lumen of aortic wall, but not in the outermost layer in which NM myosin is present exclusively. Western blotting and immunofluorescence assays indicate that the foetal aortic SM is specifically labeled by all the three anti-NM myosin antibodies. However, immunoreactivity of aortic SM with NM-F6 and NM-A9 disappears completely around birth. Conversely, NM-G2 binding is maintained during post-natal development up to day 45; between day 45 and day 90 immunoreactivity of aortic SMC with this antibody diminished progressively, without disappearing, in a small number of cells. In aortic SMC cultures from foetal and adult rabbits, NM myosin immunoreactivities appear to be differently distributed, i.e. according to the stress fiber system (NM-F6 and NM-G2), in a diffuse manner (NM-A9) or mainly localized at the level of the cortical cytoplasm (NM-G2). The fact that a different pattern of NM myosin antigenicity can also be shown in other cell types, such as in the endothelium and the cardiac pericytes as well as in the renal parenchyma, is consistent with the existence of multiple NM myosin in vascular SM isoforms whose expression is developmentally regulated.

Calcium antagonists and vascular smooth muscle cells in atherogenesis

Vascular smooth muscle cells (SMCs) play a key role in the development of atherosclerotic lesions. Vascular smooth muscle, however, does not represent a homogeneous tissue. Using myosin as a marker of the differentiation processes in development and in vascular disease, we have been able to demonstrate the existence of distinct SMC populations in rabbit aorta. In our studies, a specific SMC population of the aortic media showing an "immature" type of myosin isoform expression accounted for the majority of SMCs present in the atherosclerotic plaque. Nifedipine, a dihydropyridine-derived calcium antagonist, was able to decrease the size of this particular SMC population and to prevent the development of atherosclerotic lesions in hypercholesterolemic rabbits. Here we report about a similar effect obtained by treating hypercholesterolemic rabbits with nitrendipine, another dihydropyridine-derived calcium antagonist. This article also summarizes the main experimental and clinical studies conducted on the antiatherogenic effect of calcium antagonists and focuses on the mechanisms underlying this effect, particularly at the vascular SMC level.

Aortic intimal thickening and myosin isoform expression in hyperthyroid rabbits

The potential effect of thyroid hormones on the expression of cytoskeletal and cytocontractile proteins of vascular smooth muscle cells (SMCs) was examined by a panel of monoclonal antibodies and immunocytochemical procedures. L-Thyroxine was administered to adult New Zealand White rabbits for as long as 26 days, and the aortic SMC composition was studied at days 1, 2, 7, 15, and 26 from the beginning of hormonal treatment. A diffuse intimal thickening of the aorta became visible after 7 days of thyroxine administration. Histological and histochemical examination of intimal tissues from hyperthyroid rabbits revealed the presence of a homogeneous Sudan black-negative cell population. In immunofluorescence tests the intimal cells were found to be negative for antibodies specific for monocyte/macrophage or desmin and homogenously reactive (positive) for antibodies to vimentin and smooth muscle (SM) alpha-actin, thus indicating that cells present in the thickened intima were of the SM type. In addition, intimal SMCs from aortas of hyperthyroid rabbits showed a myosin isoform content similar to that found in normal developing aortic SM and in a specific medial SMC subpopulation of aortas from adult euthyroid animals. In the media underlying the intimal thickening, almost all the SMCs switched their myosin isoform expression toward the "immature" phenotype after 2 days of thyroxine treatment. When the level of thyroid hormones was reduced by propylthiouracil treatment, the medial SMC subpopulation with the immature myosin isoform content present in euthyroid rabbits completely disappeared. The study of DNA synthesis-related bromodeoxyuridine incorporation in aortas from hyperthyroid rabbits showed the presence of labeled nuclei in medial SMCs before the appearance of the intimal thickening as well as in the thickened intima and in the underlying media at days 7 and 15. These results are consistent with a specific role for thyroid hormones in inducing proliferation/migration of medial SMCs into the intima. Moreover, the switch in the expression of myosin isoforms induced by thyroid hormones appears to precede the accumulation of medial SMCs in the intima.

A nifedipine-sensitive smooth muscle cell population is present in the atherosclerotic rabbit aorta

We evaluated the ability of the Ca2+ channel blocker nifedipine to influence the severity of atherosclerotic lesions and the pattern of aortic smooth muscle cell (SMC) differentiation in cholesterol-fed New Zealand White rabbits. The animals were fed a 1% cholesterol-enriched diet for 12 weeks. After 4 weeks of the diet, some rabbits were given nifedipine (20 mg b.i.d.) for another 8 weeks without discontinuation of the cholesterol-enriched diet (experiment 1). Another group of rabbits was treated with nifedipine from the beginning of the cholesterol-enriched diet for the entire 12 weeks (experiment 2). The severity of ahterosclerotic lesions was determined by computerized planimetry, and qualitative effects of nifedipine on SMCs were studied by monoclonal antibodies specific for smooth muscle and nonmuscle myosins. In the aortic media of normal rabbits, these antibodies can identify an SMC population with an "immature" type of myosin pattern; a marked increase in the number of these cells is observed during atherogenesis. In experiment 1, we observed a marked decrease of medial SMCs with the immature type of myosin pattern, without any significant reduction in atherosclerosis severity. In experiment 2, disappearance of the previously mentioned medial SMC population was accompanied by a dramatic slowing of intimal lesion development. These results indicate that nifedipine treatment is effective in reducing atherosclerotic lesions only when given from the beginning of a cholesterol-enriched diet. Delay of nifedipine administration until the fourth week of the cholesterol-enriched diet fails to halt progression of the disease. The observed antiatherosclerotic activity can be attributable to a direct effect of the drug on the medial SMC population, which increases during the course of experimental atherogenesis.

Sympathetic drive and vascular damage in hypertension and atherosclerosis

Current knowledge of the links between the sympathetic nervous system and vascular damage in hypertension and atherosclerosis is summarized. The main mechanisms leading to the structural changes of the arterial wall as a consequence of enhanced adrenergic drive are reported. Hemodynamic mechanisms, including increase in pressure leading to changes in the arterioles and alteration of flow pattern with impact mainly in the large arteries, respectively, account for the typical target organ damage observed in hypertension and is involved in the development of atherosclerotic lesions. Regarding the direct effect of catecholamines, the atherogenic effects of epinephrine and norepinephrine in the absence of changes in blood pressure and cholesterol levels have been demonstrated in vivo in monkeys and rabbits. In rats, catecholamine administration induces polyploidization of aortic smooth muscle cells in vivo and in vitro. Regarding the effects of lipid metabolism, adrenergic stimulation may induce free fatty acid transformation into triglycerides with secondary increase in very low density lipoprotein plasma levels and decrease of very low density lipoprotein transformation into high density lipoprotein through circulating lipoprotein lipase inhibition. Catecholamines may also increase cholesterol levels of the arterial wall, probably by triggering the acyl-cholesterol-acyl-transferase activity. Finally, indirect evidence of the pathogenetic role played by the sympathetic system in the development of vascular disease derives from the results of experiments showing that sympatholytic agents are capable of reducing both medial hypertrophy and atherogenesis. beta-Blockers, alpha- and beta-blockers, and centrally acting sympatholytic agents not only ameliorate hemodynamics but also appear to inhibit the direct effects of catecholamines on the arterial wall.

The idiopathic dilated cardiomyopathy in man. A biochemical and molecular study on myosin

We studied subunit composition and Ca(++)-activated ATPase activity of myosin isolated from atria and ventricles of hearts explanted from patients suffering from idiopathic dilated cardiomyopathy. At variance with previously published data, we have been unable to detect in the ventricular subendocardial layers a significant amount of myosin atrial-like light chain 1 (ALC1), which has been reported to be related to some hemodynamic features of the hypertrophied and failing heart. Such a subunit was not visible in the septum and in the subepicardial layers either. On the contrary, in both atria a ventricular-like light chain 2 (VLC2) was found. The nature of this additional light chain was confirmed on the basis of two-dimensional electrophoresis and immunoblotting techniques with polyclonal antibodies reacting with VLC2. In these patients we also observed a depressed Ca(++)-activated ATPase activity, both in atrial and ventricular myosin. The explanation for this finding in ventricles still remains obscure since neither myosin light chains, nor myosin heavy chains showed any difference between patients with dilated cardiomyopathy and controls. On the contrary, in atria we clearly identified changes consistent with the expression of myosin heavy chains of ventricular type and VLC2, which can account for the depressed Ca(++)-activated ATPase activity.

Myosin isoform expression and smooth muscle cell heterogeneity in normal and atherosclerotic rabbit aorta

Two monoclonal antimyosin antibodies, Western blotting experiments, and immunofluorescence procedures were used to investigate myosin isoform expression in normal and atherosclerotic aortas of adult rabbits. The SM-E7 antibody reacted with the two myosin heavy chain (MHC) isoforms of smooth muscle (SM) type (SM-MHC-1 and SM-MHC-2) expressed in the adult rabbit aorta. The NM-G2 antibody recognized an epitope shared by the nonmuscle (NM) myosin heavy chains (NM-MHC) present in fibroblasts, macrophages, lymphocytes, and platelets. Two smooth muscle cell (SMC) populations were identified in the medial layer of normal adult aorta, namely cells that contained SM myosin exclusively and cells that showed the coexistence of SM and NM myosin isoforms. The size of the cell population with double myosin isoform content increased markedly during experimental atherogenesis and represented by far the predominant SMC phenotype in the atherosclerotic plaque. Western blotting analysis performed on crude extracts from the atherosclerotic plaque showed the presence of SM-MHC-1 and NM-MHC isoforms in this tissue. Co-expression of SM and NM myosin at the molecular and the cellular level were found in aortic tissue during the early stages of development. These results indicate that in experimental atherosclerosis, the accumulation in the plaque of SMC with an "immature" pattern of myosin isoform expression is accompanied by similar modifications in the differentiation pattern of SMC of the underlying media.

Myosin isoforms and cell heterogeneity in vascular smooth muscle. I. Developing and adult bovine aorta

Monoclonal anti-smooth muscle (SM-E7, SM-F11, and BF-48) and anti-nonmuscle (NM-A9 and NM-G2) myosin antibodies, Western blotting, and immunocytochemical procedures were used to study myosin isoform composition and distribution in the smooth muscle (SM) cells of bovine aorta differentiating in vivo and in vitro. Two myosin heavy chain (MHC) isoforms were identified by SM-E7 in adult aorta: SM-MHC-1 (Mr = 205 kDa) and SM-MHC-2 (Mr = 200 kDa), respectively. When tested with the SM-F11 antibody, SM-MHC-2 isoform showed distinct antigenic properties compared to SM-MHC-1. Two bands of 205 and 200 kDa were also present in the aortic SM tissue from 3-month-old fetus and were equally recognized by the BF-48 antibody. The 200-kDa SM myosin isoform was labeled by SM-F11 but not by SM-E7, thus indicating the existence of a fetal-specific SM-MHC-2 isoform. At the cellular level, both developing and adult bovine aortic tissues showed the existence of distinct patterns of myosin isoform expression. Three or even more aortic cell populations are differently distributed in areas which appear as (1) a network of interconnecting sheet-like or compact tissue (early fetus) and (2) enriched of collagenous-elastic or muscular tissue (adult animal). In addition, the SM-MHC-2 isoform of the fetal type appears to be uniquely distributed in cultured SM cells grown in vitro from adult bovine aortic explants. Our data indicate that in bovine aorta (1) MHC isoform expression is developmentally regulated and (2) the distribution of myosin isoforms is heterogenous both among and within aortic cells. These findings may be related to the distinct physiological properties displayed by SM during vascular myogenesis.

Nonmuscle and smooth muscle myosin isoforms in bovine endothelial cells

A panel of monoclonal antibodies, specific for human platelet (NM-A9, NM-F6, and NM-G2) and for bovine smooth muscle (SM-E7) myosin heavy chains (MHC), were used to study the composition and the distribution of myosin isoforms in bovine endothelial cells (EC), in vivo and in vitro. Using indirect and double immunofluorescence techniques, we have found that in the intact aortic endothelium there is expression of nonmuscle MHC (NM-MHC), exclusively. By contrast, hepatic sinusoidal endothelium as well as cultured bovine aortic EC (BAEC) in the subconfluent phase of growth show coexistence of NM- and smooth muscle MHC (SM-MHC) isoforms. SM myosin immunoreactivity disappears when cultured BAEC become confluent. In this phase of cell growth, NM-MHC isoforms are localized differently within the cells, i.e., in the cytoplasm around the nucleus or in the cortical, submembranous region of EC cytoplasm. A third type of intracellular distribution of NM-MHC immunoreactivity was evident in the cell periphery of binucleated, confluent BAEC. These data indicate that (1) several myosin isoforms are differently distributed in bovine endothelia; and (2) SM myosin expression and the specific subcellular localization of NM myosin isoforms within EC might be regulated by cell-cell interactions.

Changes in ventricular creatine-kinase with progression and regression of cardiac hypertrophy in hypertensive rats

We studied the distribution of four isoenzymes of creatine-kinase (MM, MB, BB and the mitochondrial) in 13 renovascular hypertensive rats and five age-matched controls. After 6 weeks of hypertension, seven rats were treated with captopril (2 mg/kg daily) for 4 weeks and the other six were left untreated for 4 weeks. After the rats were killed an adaptive increase in MB and BB was found at the expense of MM in the hypertensive rats compared with the controls. The captopril-treated rats displayed persistently higher levels of both MB and BB than the controls. Therefore, the regression in cardiac hypertrophy that is achieved by captopril is accompanied by persistence of the isoenzymic pattern that leads to better use of energy-rich phosphates.

Prevention of aortic hypertrophy in spontaneously hypertensive turkeys

In spontaneously hypertensive turkeys, both high blood pressure and high catecholamine levels play a role in the development of vascular hypertrophy. We studied the effect of labetalol, an alpha- and beta-blocking drug, on the aortic media. Seventeen turkeys were given increasing doses of the drug (20-35 mg/kg daily) from the 2nd to the 35th week of age; 13 control birds were given a daily placebo. The actively treated turkeys showed significantly lower values of blood pressure and a lower heart rate compared with the controls throughout the study period. After the turkeys had been killed, seriate histological sections taken from the abdominal aorta near the bifurcation were used for a three-dimensional assessment of the aortic media by computerized morphometry. The volume of aortic media was significantly lower in the labetalol-treated birds than in the controls. This was also observed in the non-responder turkeys. This finding indirectly supports the view that catecholamines may play a major but independent role in the development of vascular hypertrophy.

Ventricular myosin and creatine-kinase isoenzymes in hypertensive rats treated with captopril

In the myocardium, myosin and creatine kinase isoforms possess different capacities for using O2 and energy-rich phosphates. We studied electrophoretically the distribution of these isoforms in 19 hypertensive rats (two-kidney, one clip model of hypertension) and in age-matched controls. After 6 weeks of hypertension, seven rats were treated with captopril (2 mg/kg daily) for 4 weeks, six were left hypertensive for another 4 weeks, and the remaining rats were killed under ether anesthesia. In the latter, ventricular mass was significantly higher than in controls; V3 isomyosin was 32.3 +/- 6.8% versus 0%, and both creatine kinase-MB and -BB were increased at the expense of creatine kinase-MM (creatine kinase-MB = 29 +/- 2.8% vs. 14.7 +/- 1.8%, p less than 0.001; creatine kinase-BB = 3.1 +/- 0.6% vs. 1.7 +/- 0.8%, p less than 0.001). After 10 weeks of hypertension, ventricular mass, V3 isomyosin, and both creatine kinase-MB and -BB isoforms were found to be persistently higher than in controls. At the same time, captopril-treated rats showed reduced but not normalized blood pressure levels, normalized ventricular mass, and prevalence of the V1 isomyosin (56.9 +/- 22% vs. 47.9 +/- 23.8% in normotensive controls, p = NS). However, higher levels of creatine kinase-MB and -BB were still found in these rats in comparison with the normotensive controls (creatine kinase-MB = 22.4 +/- 5.4% vs. 15.8 +/- 2.8%, p less than 0.025; creatine kinase-BB = 2.3 +/- 0.1% vs. 1.8 +/- 0.3%, p less than 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

Myosin heavy-chain isoforms in adult and developing rabbit vascular smooth muscle

Two monoclonal antibodies specific for smooth muscle myosin (designated SM-E7 and SM-A9) and one monoclonal anti-(human platelet myosin) antibody (designated NM-G2) have been used to study myosin heavy chain composition of smooth muscle cells in adult and in developing rabbit aorta. Sodium dodecyl sulfate/polyacrylamide gel electrophoresis and Western blotting experiments revealed that adult aortic muscle consisted of two myosin heavy chains (MCH) of smooth muscle type, named MHC-1 (205 kDa), and MHC-2 (200 kDa). In the fetal/neonatal stage of development, vascular smooth muscle was found to contain only MHC-1 but not MHC-2. Non-muscle myosin heavy chain, which showed the same electrophoretic mobility as the slower migrating MHC, was expressed in an inverse manner with respect to MHC-2, i.e. it was detectable only in the early stages of development. The distinct pattern of smooth and non-muscle myosin isoform expression during development may be related to the different functional properties of smooth muscle cells during vascular myogenesis.

Retention of haematoporphyrin in the aorta of hypertensive rats: in-vivo and in-vitro studies

Porphyrins are known to be accumulated and retained by tumours and atherosclerotic plaques. This property has been used for a new therapeutic approach called photodynamic therapy. In this study we assessed whether the presence of arterial hypertension could modify porphyrin turnover in the vascular wall. At various times after intravenous injection, haematoporphyrin concentration was assessed by a spectrophotofluorimetric method in the aortas of normotensive and hypertensive rats. Moreover, we studied the binding of haematoporphyrin to cultured smooth muscle cells obtained from normotensive and hypertensive rats. Larger amounts of haematoporphyrin were accumulated by the aorta of hypertensive rats and cleared at a slower rate, compared with normotensive rats. As for in-vitro experiments, cultured smooth muscle cells from hypertensive rats bound larger amounts of haematoporphyrin than cells from normotensive rats.

Lipoprotein binding to cultured aortic smooth muscle cells from normotensive and hypertensive rats

Little is known about the pathophysiological mechanisms responsible for the higher incidence of atherosclerosis in hypertensive subjects. In view of the known atherogenic role of low-density lipoproteins (LDL), the aim of the present study was to evaluate possible differences in LDL binding to cultured aortic smooth muscle cells from normotensive and hypertensive rats. We studied the time-dependence and dose-dependence of LDL binding to both cell types. Low density lipoprotein binding to smooth muscle cells from the hypertensive rat was significantly higher than that to smooth muscle cells from the normotensive rat. This mechanism might explain the higher incidence of atherosclerotic lesions observed in hypertension.

Hematoporphyrin binding to cultured aortic smooth muscle cells from spontaneously atherosclerotic turkey

Porphyrins are known to be accumulated in vivo by tumors and atherosclerotic plaques. We studied the interaction of cultured aortic smooth muscle cells (SMC) from spontaneously atherosclerotic Broad Breasted White Turkeys (BBWT) with free hematoporphyrin (Hp) and low density lipoprotein (LDL)-Hp complexes. A significantly higher binding of LDL-Hp to SMC as compared to free Hp was observed. These data indicate that porphyrin binding to vascular SMC represents a possible mechanism for porphyrin accumulation by atherosclerotic plaques. This process is mediated, at least in part, by LDL.

Catecholamine-induced cardiovascular disease in the spontaneously hypertensive and atherosclerotic turkey

The interest evoked by the Broad Breasted White Turkey (BBWT) as an animal model for studying the cardiovascular damages produced by hypertension and catecholamines is mainly due to the fact that hypertension is spontaneous and tissue and circulating catecholamines, especially norepinephrine, are extremely high. In this paper we focused our attention on three characteristic pathophysiological features displayed by these animals which are strictly related, as well as in humans, to the elevated blood pressure values and to catecholamine action. We also described the possibility of modifying the development of some of these lesions with pharmacological interventions liable to antagonize the peripheral effects of norepinephrine and epinephrine. The dissecting aneurysm of the aorta accounts for 5-10% of sudden deaths in this animal strain. It can be prevented by lowering blood pressure, especially with beta-blockers, and facilitated by MAO-inhibitors. The degree of cardiac hypertrophy is remarkably high and unexpectedly characterized by the synthesis of a "fast" V1-like isomyosin with high Ca++ activated ATPase activity, oxygen consumption and speed of muscle shortening. Neither the reduction of the degree of cardiac hypertrophy, nor treatment with labetalol alone were able to modify this peculiar pattern. In spite of having very high levels of high-density-lipoproteins, which are known to be protective against atherosclerosis, this animal develops a severe atheromatous disease especially in the abdominal aorta, where the cellular growth has also been proven to be in vitro more pronounced than in the thoracic tract. Treatment with beta-blockers reduced the severity and extent of the lesion even in absence of a significant reduction in blood pressure.

Ventricular myosin pattern of spontaneously hypertensive turkeys is unaffected by labetalol treatment

In most animal species, left ventricular hypertrophy due to pressure overload is associated with an advantageous increase of the "slow" V3 isomyosin. In contrast, in spontaneously hypertensive turkeys, the development of left ventricular hypertrophy is associated with the synthesis of a "fast" V1-like isomyosin, with high incidence of cardiac failure. This could be related to the high catecholamine levels found in these animals. This is why we studied the ventricular myosin pattern after lowering of blood pressure and regression of cardiac hypertrophy obtained by means of labetalol, and alpha- and beta-blocking drug which inhibits the effects of catecholamines. From the 2nd to the 32nd week of age, 22 turkeys were treated with increasing doses of p.o. labetalol (from 20 to 35 mg/kg body weight daily) and 16 other turkeys were given daily p.o. placebo. Blood pressure and heart rate were periodically measured by an indirect method. After sacrifice, the degree of cardiac hypertrophy was evaluated by the biventricular weight to body weight ratio, ventricular myosin was purified, Ca++-activated ATPase activity assessed, and ventricular myosin pattern was determined by two-dimensional gel electrophoresis of myosin heavy chains. Plasma and cardiac catecholamines were measured by high performance liquid chromatography. Throughout the study period, blood pressure and heart rate were significantly reduced in the labetalol-treated animals as compared to the untreated ones. At the end of the study period, the ventricular mass was significantly lower in the labetalol group. Nevertheless, no differences were observed in ventricular myosin pattern and Ca++-activated ATPase activity levels between the two groups. In the labetalol group, an increase in plasma catecholamines and only a slight, but not significant, increase in cardiac catecholamines was found. These data indicate that in spontaneously hypertensive turkeys, the synthesis of the "fast" V1-like isomyosin is not influenced by known pathophysiological stimuli like blood pressure, cardiac hypertrophy and catecholamines.

Left ventricular hypertrophy in hypertension. Changes in isomyosins and creatine-kinase isoenzymes

In hypertension, the heart of small mammals can express different isoenzymic forms of proteins under the influence of overload and other modulating factors. The increase in ventricular mass is generally paralleled by progressive changes in the isoforms of at least two proteins that are involved in the contraction process, namely, myosin and creatine-kinase. This review summarizes the biochemical and molecular changes occurring during progression and with regression of cardiac hypertrophy in rats, humans, and other animals, and focuses on the role played by antihypertensive drugs in modulation of ventricular isomyosins. The implications of these observations for humans remain to be fully determined.

Changes in rat ventricular isomyosins with regression of cardiac hypertrophy

The changes in ventricular isomyosin composition and Ca2+-activated ATPase activity occurring with regression of both hypertension and cardiac hypertrophy were investigated by using polyacrylamide gel electrophoresis under nondenaturing conditions, heavy chain peptide mapping, and an enzymatic assay. Eight control male Wistar rats and 14 two-kidney, one clip (Goldblatt II) hypertensive rats were studied from the fifth week of age. At 10 weeks of age, five Goldblatt II rats and four normotensive controls were killed. Five other Goldblatt II rats underwent nephrectomy of the ischemic kidney, which resulted in subsequent normalization of blood pressure. The remaining four control, four Goldblatt II rats, and five nephrectomized rats were killed at 15 weeks of age. Both the 10- and 15-week-old hypertensive rats had a significantly higher (p less than 0.001) biventricular weight to body weight ratio than the age-matched controls (3.84 +/- 0.76 X 10(-2) vs 2.75 +/- 0.25 X 10(-2); 5.93 +/- 2.26 X 10(-2) vs 2.65 +/- 0.17 X 10(-2]. The 15-week-old nephrectomized rats had a biventricular weight to body weight ratio (2.90 +/- 0.25 X 10(-2] close to that of age-matched controls and significantly lower (p less than 0.05) than that of age-matched hypertensive rats. In both the 10- and 15-week-old hypertensive rats left ventricular myosin Ca2+-activated ATPase activity was significantly lower (p less than 0.001) than in the age-matched controls (0.44 +/- 0.03 vs 0.59 +/- 0.06; 0.24 +/- 0.05 vs 0.48 +/- 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Progression and regression of cardiac hypertrophy in hypertensive rats: biochemical and molecular changes in ventricular myosin

We investigated the changes in ventricular isomyosin composition and Ca2+-activated ATPase activity during progression and regression of hypertension and cardiac hypertrophy. Eight control male Wistar rats and 14 Goldblatt-II (two-kidney, one clip) hypertensive rats were studied from the 5th week of age. Five of the Goldblatt-II rats underwent nephrectomy of the ischaemic kidney after 5 weeks, with normalization of blood pressure. The hypertensive rats showed a higher biventricular weight to body weight ratio (P less than 0.02), a lower ATPase activity (P less than 0.005), and an increased expression of 'slow' isomyosins in comparison with the age-matched controls. These changes were more pronounced at 15 than at 10 weeks of age. The 15-week-old nephrectomized rats showed the same degree of cardiac hypertrophy, ATPase activity and isomyosin pattern as the age-matched controls. In conclusion, the changes in ventricular myosin observed during the progression of cardiac hypertrophy regressed after normalization of blood pressure and ventricular mass.

Isomyosin redistribution in chronic pressure overload: comparison between peptide mapping and electrophoresis under non-denaturing conditions

Chronic pressure overload induces a redistribution in myosin isoenzymes as demonstrated by Ca++-activated ATPase activity, electrophoresis under non-denaturing conditions and immunohistochemistry. We compared, in two groups of renal hypertensive rats and control rats, the isoenzymic patterns obtained by electrophoresis under non-denaturing conditions with those observed after heavy chains digestion with S. Aureus V8 protease. In the hypertensive animals in which a shift towards the "slow" V2 and V3 isomyosins was evident, peptide mapping always gave origin to a band which was not present in the controls. Since we consider this peptide as a marker of the redistribution towards the "slow" isoforms, peptide mapping according to Cleveland appears to be a simple and useful method to assess differences in isomyosin composition, at least between hypertrophic pressure-overloaded and normal rat ventricles. Moreover, in our experience this technique is simple, the patterns obtained from highly purified substrates are very reproducible and the digestion allows easy and clear comparisons.

Biochemical characterization of ventricular myosin from spontaneously hypertensive turkeys

Several stimuli are able to alter the synthesis of cardiac myosin isoenzymes. Particularly in the rat a shift toward a low-ATPase isomyosin is generally observed during development and in cardiac hypertrophy due to pressure overload. On the contrary in spontaneously hypertensive turkeys both ageing and the increasing degree of cardiac hypertrophy are accompanied by a different behaviour of ventricular myosin. In fact in a previous study we have shown that the Ca2+-activated ATPase activity of ventricular myosin increases about three folds from young normotensive to old hypertensive animals. Accordingly the peptide pattern obtained after chymotryptic digestion of myosin showed that some peptides, which are not evident or barely discernible in young animals, are present in the adult ones. In this study we compare the ventricular myosin from young normotensive and adult hypertensive turkeys with atrial myosin. The results obtained suggest that in the ventricles of hypertensive turkeys the synthesis of an isomyosin with biochemical properties close to those of atrial myosin occurs.

The surface measurement of aortic atherosclerosis: critical survey and comparison with histologic findings

Both the reproducibility of the surface measurements of aortic atherosclerosis and the agreement between gross inspective and histologic changes were evaluated. Aortas from male broad breasted white turkeys were chosen because of the high incidence of spontaneous and typical atherosclerotic lesions in this animal strain. Ten male turkeys were killed at 33 weeks of age. The aortas were removed including the iliac bifurcation and stained with Sudan III. Each aorta was processed blindly by four pathologists and a computerized planimeter to determine normal areas, sudanophilic areas and areas covered by plaques. The analysis of variance showed significant differences among the four pathologists' measurements of sudanophilic areas (P less than 0.01) and areas covered by plaques (P less than 0.001). The coefficients of variation among the four determinations made by one pathologist on the same aorta were 3.6% for total aortic area; 10.08% for sudanophilic area; 47.6% for the area covered by plaques. On each aorta histology was performed at the level where all the four pathologists recorded the same findings at inspection, namely a normal area, a sudanophilic area, and an area covered by plaques. Important discrepancies occurred between findings at inspection and those of histologic examination: the ten areas classified as "normal" by all the four pathologists at inspection were shown at histologic examination to be normal in only two cases. In one case a musculo-elastic layer and in seven cases a fibro-elastic layer were found. The ten areas classified as "sudanophilic" by all the observers showed a fibro-elastic layer in five cases, a musculo-elastic layer in two cases and normal findings in three cases. The ten areas classified as "covered by plaques" displayed a typical atherosclerotic plaque in all cases but one. In conclusion, our data indicate that the reproducibility of gross inspective methods is low. Important discrepancies exist between findings at inspection and histologic examinations. The relevance of these findings remains to be established as far as the assessment of human atherosclerosis is concerned.

Propranolol-induced changes in ventricular isomyosin composition in the rat

The ventricular isomyosin composition in the rat is characterized by three isoenzymes, V1, V2, and V3, with high, intermediate, and low Ca++-activated ATPase activity, speed of muscle shortening, and contractile economy. In this study, we examined the effects of propranolol on ventricular isomyosin composition in the rat. Eight 4-week-old male Wistar rats were treated from 4 to 12 weeks of age with daily 10 mg/kg subcutaneous doses of propranolol; four control rats were given subcutaneous distilled water. At the end of the treatment period, the efficacy of beta blockade was confirmed by isoproterenol test in some rats from each group. After the rats were killed left ventricular myosin from both control and propranolol-treated animals was purified and tested for Ca++-activated ATPase activity. Ventricular isomyosin composition was studied by gel electrophoresis in non-denaturing conditions. Heart rate was significantly lower in the propranolol group, while no differences in blood pressure, body weight, or ventricular weight were found between the two groups. Lower Ca++-activated ATPase activity values and a higher expression of myosin isoenzymes V2 and V3 were found in propranolol-treated rats. Possible links between the observed shift in ventricular isomyosin composition and the well-known modifications in myocardial contractility and oxygen consumption occurring after chronic propranolol administration remain to be established.

[Evaluation of the efficacy of various hypotensive drugs in broad-breasted white turkeys as an experimental model of arterial hypertension with high catecholamine levels]

Male Broad Breasted White Turkeys (BBWT) represent an experimental model of arterial hypertension characterized by high levels of circulating and tissue catecholamines. We thought interesting to evaluate the efficacy of the long term treatment with different antihypertensive drugs. 59 male BBWT were studied, divided in five groups. The first group (13 animals) was treated with placebo; the second (14 animals) with oxprenolol 4 mg/Kg/q.d.; the third (10 animals) with labetalol 25 mg/Kg/q.d.; the fourth (11 animals) with verapamil 15 mg/Kg/ q.d.; the fifth (11 animals) with captopril 8 mg/Kg/ q.d. and furosemide 2,5 mg/Kg/q.d. All drugs were given p.o, from the 8th to the 33rd week of age. Weekly or every two weeks Blood Pressure (BP) and Heart Rate (HR) were measured by an indirect method. In all animals BP progressively increased and HR progressively decreased with age. Only the labetalol-treated animals showed a significant reduction of BP and HR through the study period as compared with the placebo-treated animals. These results confirm the preminent role played by the high levels of circulating catecholamines in determining and maintaining the arterial hypertension.