Comparative analysis of diagnostic methods and risk factors for Aelurostrongylus abstrusus infection in brazilian cats.

This study aimed to prospectively evaluate the risk factors of infection by Aelurostrongylus abstrusus in Brazilian cats with cough and/or radiographic changes, using as diagnostic tools the Baermann method (BM), polymerase chain reaction (PCR) of feces, bronchoalveolar lavage fluid (BALF), and cytology. Forty-three cats that were presented with cough or lung radiographic abnormalities compatible with bronchoalveolar disease were included in the study. After clinical evaluation, feces samples were collected to investigate lungworm parasitism through BM and PCR. BALF was performed to provide samples for cytology, bacteriology, and fungal culture. Stool PCR was considered the gold standard for diagnosis tests, and the other methods were evaluated by their agreement. PCR presented 74% (32/43) of positivity for A. abstrusus, while in the BM, 41% (18/43) were positive. BM showed sensitivity of 56.25% and specificity of 100% when compared with PCR. No larva was found in the cytological evaluation of 21 BALF samples. Lungworm is an important cause of bronchopulmonary disease in domestic cats in Brazil and should be included as a differential diagnosis when a cat is presented with cough or radiographic abnormalities. BM is a sensitive, non-invasive, and cheap technique to diagnose the disease, but it is not as sensitive as PCR.

High fidelity defines the temporal consistency of host-parasite interactions in a tropical coastal ecosystem.

Host-parasite interactions represent a selective force that may reduce hosts' lifespan, their reproductive success and survival. Environmental conditions can affect host-parasite communities, leading to distinct patterns of interactions with divergent ecological and evolutionary consequences for their persistence. Here, we tested whether climatic oscillation shapes the temporal dynamics of bird-haemosporidian associations, assessing the main mechanisms involved in the temporal dissimilarity of their interactions' networks. For two years, we monthly sampled birds in a tropical coastal ecosystem to avian malaria molecular diagnosis. The studied networks exhibited high specialization, medium modularity, with low niche overlap among parasites lineages. Moreover, alpha and ß-diversity of hosts, parasites and their interactions, as well as the structure of their networks were temporally consistent, i.e., stable under fluctuations in temperature or precipitation over seasons. The structure and temporal consistency of the studied antagonistic networks suggest a high fidelity between partners, which is likely relevant for their evolutionary persistence.

The Importance of Forest Simplification and Litter Disturbance in Defining the Assembly of Ground-Foraging Ants.

Currently, we are facing many ecosystem changes derived from years of anthropogenic disturbances. Habitat simplification stands out among human-derived impacts, due to its detrimental effects on vegetation structure and associated biota. Here, we assessed the effects of litter disturbance and forest simplification on a tropical ground-foraging ant community. To do that, we tested whether ant richness will be negatively affected by litter disturbance and habitat simplification. Additionally, we tested whether litter disturbance affects the time of resource discovery and dominance, and if so, whether its effects are intensified by forest simplification. This study occurred at Rio Doce State Park, a preserved area of Atlantic Forest in Southeastern Brazil. We experimentally simulated litter disturbance by removing the leaf litter and superficial soil layer in a mahogany monoculture forest and preserved Atlantic Forest. We sampled ants using paired-mixed baits of protein and carbohydrate in 12 points, half of them in each forest type. As expected, we found higher richness in the preserved and non-disturbed forest. Moreover, resource discovery was faster in disturbed monoculture, but bait dominance was higher in the undisturbed preserved forest. Litter heterogeneity seems to play an important role in determining ant dispersion and intra-specific communication, as we observed that litter disturbance impacts were strengthened by forest simplification. Our results highlight the efficiency of ground-foraging ants as bioindicators of disturbance and habitat quality. Moreover, our study indicates how distinct types of disturbances can act synergistically, changing the assembly of associated biota.

Epidemiological and Pathological Characterization of Feline Injection Site Sarcomas in Southern Brazil.

Feline injection site sarcoma (FISS) is a mesenchymal neoplasm with highly malignant characteristics. These tumours originate in anatomical sites where there has been previous parenteral administration of medicinal substances or implantation of medical devices. The aim of this study was to investigate the epidemiological and pathological features associated with FISS in the southern region of Brazil. The database of the Department of Veterinary Pathology of the Federal University of Rio Grande do Sul was searched for excisional and incisional biopsy samples compatible with FISS submitted between 2007 and 2017. Biopsy reports were reviewed and epidemiological information, including breed, age and sex of affected cats, as well as gross findings including anatomical location and size of the tumour and the presence of tissue invasion, were extracted. Eighty-nine samples were selected based on the established criteria. Most animals were of undefined breed and were female cats with a median age of 10 years. Grossly, 84.8% of the tumours were >2 cm in diameter. Regarding anatomical location, 34.9% of the tumours were located in the subcutaneous tissue of the thoracic wall, 29.2% in the flank, 21.3% in the interscapular region and 14.6% in the limbs. Histologically, the tumours originated in the subcutaneous tissue and were diagnosed as malignant mesenchymal neoplasms. Most were compatible with fibrosarcomas, but variants with features of pleomorphic sarcoma or chondrosarcoma were recognized. All tumours exhibited areas of necrosis and peripheral inflammatory infiltrate, composed predominantly of lymphocytes, plasma cells and macrophages. The results of this study suggest the need for dissemination of information on FISS epidemiology and guidelines for management of this tumour to veterinarians in the region.

Dispneia expiratória restritiva em um gato com fibrose pulmonar idiopática: relato de caso / Restrictive expiratory dyspnea in a cat with idiopathic pulmonary fibrosis: case report

As doenças pulmonares intersticiais constituem um grupo de doenças difusas do parênquima pulmonar, no qual a fibrose pulmonar intersticial está incluída. Histologicamente, esta se caracteriza por hiperplasia de pneumócitos tipo II, hiperplasia ou hipertrofia de músculo liso e fibrose. Embora a patogenia da fibrose pulmonar intersticial não esteja bem elucidada, devido às semelhanças microscópicas encontradas nos pneumócitos tipo II em felinos e na forma familiar da doença em humanos, acredita-se que haja caráter genético para o seu desenvolvimento. Os sinais clínicos frequentemente relatados incluem desconforto respiratório, cianose, letargia e perda de peso. Devido ao caráter progressivo e à ausência de tratamento específico, a doença apresenta prognóstico desfavorável. Foi atendida uma gata de 12 anos de idade, com histórico de dispneia há 20 dias. Ao exame clínico, o animal apresentou dispneia expiratória restritiva, crepitação à ausculta torácica e foi visualizado padrão intersticial ao exame radiográfico do tórax. A paciente foi submetida à punção com agulha fina de tecido pulmonar e veio a óbito algumas horas após o procedimento, apresentando insuficiência respiratória aguda. No exame histológico do tecido pulmonar, foi verificada a ocorrência de fibrose pulmonar idiopática. O objetivo do presente trabalho é relatar um caso de dispneia expiratória restritiva em um felino doméstico devido à fibrose pulmonar idiopática, já que, segundo o conhecimento dos autores, não há nenhum relato da ocorrência da doença no país.(AU)

Interstitial lung diseases are a group of diffuse parenchymal lung diseases in which interstitial lung fibrosis is included. Histologically, it is characterized by type II pneumocyte hyperplasia, hypertrophy or hyperplasia of smooth tissue and fibrosis. Although the pathogenesis of interstitial lung fibrosis has not been elucidated, due to the microscopic similarities found in type II pneumocytes in cats and familial form of the disease in humans, it is believed that there is a genetic trait for development. The frequently reported clinical signs include respiratory distress, cyanosis, lethargy, and weight loss. Due to the progressive nature and the absence of specific treatment, the disease has a poor prognosis. A 12-year-old cat with dyspnea for 20 days was assisted. The animal underwent fine needle aspiration of lung tissue and died few hours after the procedure, with acute respiratory failure. Upon histological examination of lung tissue, the occurrence of idiopathic pulmonary fibrosis was found. The aim of this study is to report a case of restrictive expiratory dyspnea in a domestic feline due to idiopathic pulmonary fibrosis, because, according to our knowledge, there is no report on the occurrence of the disease in our country.(AU)

Avaliação e comparação entre métodos de mensuração de pressão arterial sistólica em gatos hígidos conscientes / Evaluation and comparison between methods of measurement of systolic blood pressure in healthy conscious cats

Após validação de dois diferentes métodos de mensuração de pressão arterial sistólica (PAS) não invasivos ou indiretos (oscilométrico e Doppler vascular) com o invasivo ou direto (cateterização arterial - padrão ouro) em 12 gatos hígidos anestesiados de mesma faixa etária, os métodos não invasivos foram avaliados e comparados em 24 gatos hígidos e conscientes, divididos em quatro grupos de idade. Em cada animal, procedeu-se à mensuração da pressão pelos métodos Doppler e oscilométrico. O método oscilométrico foi o primeiro a ser realizado, e, logo em seguida, o método Doppler. Os valores considerados foram obtidos das médias de sete medidas consecutivas para cada método, com intervalo de 30 segundos entre elas. A primeira medida e as medidas discrepantes (variação ˃ 20% PAS), obtidas com sinais óbvios de estresse e/ou com movimentação do animal, foram descartadas. Os métodos de mensuração oscilométrico e Doppler, embora tenham apresentado médias estatisticamente diferentes em todos os grupos, quando comparados em cada grupo, apresentaram uma correlação significativa, alta e positiva. Ou seja, sempre que for obtido um valor elevado por um método, o mesmo fato ocorrerá com o outro método e vice-versa. Clinicamente, a diferença observada não é relevante, uma vez que a diferença média dos valores obtida pelos dois métodos, em cada grupo, foi menor que 1,1%.(AU)

After two different validation systolic blood pressure measurement methods (PAS), not invasive or indirect (oscillometric and doppler vascular) with invasive or direct (arterial catheterization - Gold Standard) in 12 anesthetized healthy cats of the same age group, not invasive methods were evaluated and compared in 24 healthy conscious cats, divided into four age groups. In each animal, we proceeded to measure the pressure by Doppler and oscillometric methods. The oscillometric method was the first to be performed, and, shortly thereafter, the doppler method. The values considered were obtained from averages from seven consecutive measurements for each method with an interval of thirty seconds between them. The first measurement and disparate measurements (range ˃ 20% PAS) obtained with obvious signs of stress and / or animal movement were discarded. Methods of oscillometric and doppler measurement, although statistically different averages were shown in all groups when compared, each group showed a significant high positive correlation, meaning that when a high value is obtained by a method, the same occurs with the other method, and vice versa. Clinically, the observed difference is not relevant since the mean difference values obtained by the two methods, in each group was lower than 1.1%.(AU)

Serum uric acid and its relationship with metabolic syndrome and cardiovascular risk profile in patients with hypertension: insights from the I-DEMAND study.

BACKGROUND AND AIMS: The independent role of serum uric acid (SUA) as a marker of cardio-renal risk is debated. The aim of this study was to assess the relationship between SUA, metabolic syndrome (MS), and other cardiovascular (CV) risk factors in an Italian population of hypertensive patients with a high prevalence of diabetes. METHODS AND RESULTS: A total of 2429 patients (mean age 62 ± 11 years) among those enrolled in the I-DEMAND study were stratified on the basis of SUA gender specific quartiles. MS was defined according to the NCEP-ATP III criteria, chronic kidney disease (CKD) as an estimated GFR (CKD-Epi) <60 ml/min/1.73 m(2) or as the presence of microalbuminuria (albumin-to-creatinine ratio ≥2.5 mg/mmol in men and ≥3.5 mg/mmol in women). The prevalence of MS, CKD, and positive history for CV events was 72%, 43%, and 20%, respectively. SUA levels correlated with the presence of MS, its components, signs of renal damage and worse CV risk profile. Multivariate logistic regression analysis revealed that SUA was associated with a positive history of CV events and high Framingham risk score even after adjusting for MS and its components (OR 1.10, 95% CI 1.03-1.18; P = 0.0060; OR 1.28, 95% CI 1.15-1.42; P < 0.0001). These associations were stronger in patients without diabetes and with normal renal function. CONCLUSIONS: Mild hyperuricemia is a strong, independent marker of MS and high cardio-renal risk profile in hypertensive patients under specialist care. Intervention trials are needed to investigate whether the reduction of SUA levels favorably impacts outcome in patients at high CV risk.

Fixed combinations of delapril plus indapamide vs fosinopril plus hydrochlorothiazide in mild to moderate essential hypertension.

This 12-week randomized, parallel-group, multicenter study compared fixed combinations of delapril (D) 30 mg plus indapamide (I) 2.5 mg and fosinopril (F) 20 mg plus hydrochlorothiazide (H) 12.5 mg in 171 adult patients with mild to moderate essential hypertension. After a 2-week placebo run-in, sitting and standing systolic (SBP) and diastolic blood pressure (DBP) was measured by conventional sphygmomanometry. The primary efficacy endpoint was the percentage of normalized (sitting DBP < or =90 mm Hg) and responder (sitting DBP reduction of 10 mm Hg or DBP < or =90 mm Hg) patients. Treatment effects were analyzed in the intention-to-treat (ITT; n = 171) and the per-protocol (PP; n = 167) populations. The percentage of normalized and responder patients did not differ significantly between the D + I (87.4% and 92%) and the F + H (81% and 86.9%) ITT groups. Similar results were seen in the PP population. In ITT and PP patients, sitting and standing SBP and DBP values were comparable at baseline in the two groups and were significantly (P<.01) and similarly reduced at weeks 4, 8, and 12. Neither treatment induced reflex tachycardia, and both regimens were well tolerated. Four patients in the F + H group dropped out because of adverse events. In this study, the efficacy and safety of D + I were comparable to those of F + H in patients with mild to moderate essential hypertension.

The role of losartan in cost-effective hypertension control.

Despite recent guidelines emphasising the need for aggressive treatment in patients with elevated blood pressure, the control of hypertension in Europe and the USA is poor, imposing a considerable burden in terms of patient morbidity and mortality, and associated healthcare costs. A major factor contributing to the suboptimal control of hypertension is the failure of patients to adhere to their prescribed therapy. Drug side-effects are an important cause of non-compliance and prescribing a well-tolerated agent that promotes good compliance is therefore the key to the cost-effective management of hypertension. Several studies have demonstrated that patients are more likely to remain on therapy with the angiotensin II antagonist losartan than other antihypertensives. Although the acquisition costs of new antihypertensives such as losartan are greater than for older drugs, such costs represent only a small proportion of the total cost of prescribing antihypertensive therapy. When accessory costs are also considered, the total cost of care with newer antihypertensives is comparable with those for diuretics. The costs involved if therapy has to be switched due to unacceptable side-effects also need to be taken into account when assessing relative cost effectiveness. Furthermore, savings may accrue from the non-haemodynamic benefits of losartan, such as improved cognitive function and renal protection. Further studies will increase awareness of the true cost effectiveness of antihypertensive drugs.

Use of statins and blood pressure control in treated hypertensive patients with hypercholesterolemia.

High serum cholesterol has been frequently reported in patients with arterial hypertension in whom it might influence the blood pressure control. The aim of this study was to compare the extent of blood pressure changes in 41 patients with hypertension and hypercholesterolemia, taking antihypertensive drugs and treated for 3 months with statins (HC-S; pravastatin or simvastatin) and compared with matched controls with high (HC-D; 44) or normal serum cholesterol (NC-D; 45) undergoing antihypertensive treatment combined with dietary treatment alone. After 3 months of follow-up, a greater reduction of systolic (SBP) and diastolic (DBP) blood pressure values was observed in HC-S patients (ASBP/DBP, -11.3 +/-3/-10.6 +/- 2%) when compared with both HC-D (deltaSBP/DBP, -6.6 +/- 2/-6.1 +/- 2%; p < 0.05) and NC-D (deltaSBP/DBP, -6.9 +/- 2/-6.8 +/- 1.5%; p < 0.05). In statin-treated patients, a slight linear relation has been found between the percentage changes in DBP and those in plasma total cholesterol (R = 0.37, p = 0.043), whereas no relation was found with SBP changes (R =0.11; p = 0.35). In conclusion, the results of this study demonstrate that the use of statins in combination with antihypertensive drugs can improve blood pressure control in patients with uncontrolled hypertension and high serum cholesterol levels. The additional blood pressure reduction observed in patients treated with statins is clinically relevant and only partially related to the lipid-lowering effect.

Cost-effectiveness calculations from trials.

EFFECTIVENESS OF ANTIHYPERTENSIVE THERAPY: Data on the effectiveness of antihypertensive therapy derived from the results of large clinical trials are of great importance, but also have a number of significant flaws and probably underestimate the real effectiveness of treatment. In the next few years much more information is likely to become available on the effects of the newer classes of drugs and thus evaluations of cost-effectiveness will have fewer limitations than at present. ECONOMIC VALUE OF SAVING A LIFE: Today, in every country worldwide, priority should be given to determining the economic cost of avoiding the morbidity and mortality caused by hypertension. Each society must decide the price per life-year gained that it is willing to pay. This is the most difficult task of all, since the economic value of saving a life is not easily evaluable.

Factors associated with the development of stable hypertension in young borderline hypertensives.

OBJECTIVES: To identify factors predisposing subjects to the development of stable hypertension and to estimate their relative importance in 70 young patients with borderline hypertension monitored for 10 years. DESIGN: Longitudinal evaluation of the incidence of stable hypertension [diastolic blood pressure (DBP) > 95 mmHg]. METHODS: Patients were examined at baseline by determination of resting blood pressure, intracellular sodium level and individual pressor response to mental arithmetic and to intravenous saline loading. They were re-examined after 10 years to assess the prevalence of established hypertension and the importance of some prognostic variables identified prospectively (age, sex, intracellular sodium level, baseline blood pressure, pressor response to stress and acute salt-sensitivity). RESULTS: The prevalence of sustained hypertension (DBP > 95 mmHg) was 35.8% after 10 years of follow-up study. Subjects developing hypertension were older (26.9 +/- 1.3 versus 21.0 +/- 1.8 years) and showed a higher percentage of family history of hypertension (92 versus 64%) and of acute salt-sensitivity (72 versus 53%). The pressor response to mental arithmetic was greater in patients who developed hypertension (systolic blood pressure 26.9 +/- 1 versus 22.7 +/- 0.9 mmHg, P = 0.005 DBP = 16.6 +/- 0.8 versus 13.1 +/- 0.7 mmHg, P = 0.005), who also showed higher levels of intracellular sodium (30.7 +/- 0.6 versus 27.3 +/- 0.5 mmol/kg, P = 0.001). The same variables were found to be related to the development of hypertension in a multivariate analysis and the concomitant presence of 4-5 risk factors was associated with a reasonable predictive power for the identification of patients at high risk (sensitivity 72%, specificity 67%, predictive accuracy 76%). CONCLUSIONS: The present study demonstrates that borderline hypertensives at high risk of stable hypertension can be identified by the concomitant evaluation of some clinical and cellular characteristics directly related to long-term development of high blood pressure.

Compliance with antihypertensive treatment.

Compliance to antihypertensive treatment is a critical factor conditioning the success of therapy. It has been calculated that, depending on the method used to monitor compliance, only 20 to 80% of treated hypertensives can be considered as good compliers. In the past years it was thought that compliance was only a patient's problem but instead, the role of the physician in determining patient's compliance is very important. He should give clear information about the risks of the disease, the advantages of therapy and how to take medicines. He should also prescribe a therapeutic scheme as simple as possible avoiding multiple drug administrations and informing patients about possible side-effects. Subjects at particular risk of poor compliance (middle aged males, still active in work, without previous cardiovascular diseases) must be particularly monitored. In any case of poor response to therapy it is important to suspect poor compliance. A standardization of the methods for recording compliance is needed especially in clinical trials. The results of experimental studies in fact can be misleading if compliance is not taken into account.

Low dose of ACE-inhibitor enhances sodium excretion in volume expanded patients with borderline hypertension.

The purpose of the present study was to separately investigate the effects of two different dosages of captopril on pressor, vascular and humoral response to acute extracellular volume expansion in patients with borderline hypertension (BHT). Thirty-five patients were randomly allocated in two groups undergoing acute saline infusion (0.40 ml/min/kg for 45 min and 0.15 ml/min/kg for 75 min)before and after a 7-day period of treatment with either placebo or captopril at the dose of 12.5 (LD-CAP) or 50 mg (HD-CAP) twice a day. At baseline the effects of LD-CAP were limited to an increase in PRA and to a decrease in plasma aldosterone whereas HD-CAP decreased systolic and diastolic blood pressure (SBP, DBP), forearm vascular resistance (FVR) and increased venous distensibility (VV(30)) as well. After saline loading patients treated with HD-CAP showed an increase in SBP, DBP not observed in patients allocated to LD-CAP. Urinary sodium excretion in response to NaCl loading was selectively enhanced by LD-CAP (+25%) whereas HD-CAP did not (+6.3%). The present data suggest that low-doses of ACE-inhibitors acting through a selective blockade of RAA not associated with hemodynamic changes can enhance the natriuretic response to acute volume expansion in borderline hypertensives.

[Problems in the treatment of arterial hypertension]. / Problemi aperti nel trattamento dell'ipertensione arteriosa.

During the last 20 years antihypertensive treatment has given excellent results in terms of prevention of cardiovascular complications. However these results, for some reasons, are less satisfactory than those theoretically possible. The problems we need to solve are many and all contribute to reduce the efficacy of therapy. First of all it is necessary to make a correct diagnosis of hypertension to avoid treating normotensive subjects. The use of continuous ambulatory blood pressure monitoring in some cases can be useful to clarify these situations and also to better evaluate the efficacy of therapeutic regimens. In the vast majority of cases, however, the traditional blood pressure recordings, if correctly performed, can give satisfactory and sufficient information. After a correct diagnosis is made the physician must start with the patient an open-minded cooperation based on confidence. He must clearly explain the goals and the methods of therapy and encourage, instead of frighten, the patient. The next step is the choice of the kind of treatment in which many factors must be kept in mind and in which the physician must have a deep knowledge of the patient and of the drugs. Treatment has a high probability rate of a good patient's compliance only if it does not cause adverse reactions and if the therapeutic scheme is simple. Studies on compliance have shown that it is possible to identify those patients at risk of low compliance even before the beginning of therapy and it has been shown that adverse reactions especially if the patient has not been informed by the doctor, can cause a dramatic fall in compliance.(ABSTRACT TRUNCATED AT 250 WORDS)

Relationship between acute suppression of plasma renin activity and lymphocyte Na+:H+ exchange rate in young patients with borderline hypertension.

The participation of the cellular sodium content and renin-angiotensin-aldosterone system in the development of high blood pressure has been frequently suggested. To elucidate the role of a mechanism responsible for renal sodium reabsorption on the time-course of renin suppression, 16 young borderline hypertensive patients were studied by analyzing the relationship between the level of baseline activation of lymphocyte Na+:H+ exchange and the degree of plasma renin activity (PRA) suppression in response to saline loading. In the whole hypertensive population, a significant correlation (R = 0.64; p < 0.01) was found between the lymphocyte Na+:H+ exchange activity and the percentage degree of PRA suppression induced by saline loading. Urinary sodium excretion was enhanced in patients with lesser activation of lymphocyte Na+:H+ exchange and greater PRA suppression (3.5 +/- 5 vs. 2.4 +/- .1 umol/min/kg; p < 0.05). These findings suggest that a mechanism influencing renal sodium reabsorption as Na+:H+ exchange could also affect the control of plasma renin activity, and concur with the development of salt-sensitive high blood pressure.

Atrial natriuretic factor response to acute volume expansion in borderline hypertension. Role of ACE-inhibition and changes in peripheral venous tone.

Abnormalities in the response of atrial natriuretic factor (ANF) to volume expansion have been reported in hypertensive-prone animals and men as well as in hypertensive patients undergoing ACE-inhibition. To investigate some of the mechanisms affecting ANF release in borderline hypertensive patients (BHT) we have studied 16 subjects by assessing their neuro-humoral and hemodynamic response to a two-hour isotonic i.v. NaCl infusion carried out during short-term administration of either placebo or captopril. ACE-inhibition increased baseline venous distensibility (VV30:1.4 vs 1.6 ml/100 ml; p < .05) and reduced the prompt (45') ANF response to saline loading (10.3 +/- 13 vs 42.7 +/- 15%; p < .05)) without affecting the overall ANF release (120':92 +/- 25 vs 65.8 +/- 20%; NS)). A significant pressor increase in response to NaCl loading was observed exclusively after ACE-inhibition (SBP: 5.2 +/- 2 vs 2.4 +/- 1%; p < .05--DBP: 7.1 +/- 3 vs 2 +/- 3%; p < .025) and occurred along with a peripheral arterial and venous constriction and with an increase in plasma levels of an endogeneous Na+/K+ATPase inhibitor (8.8 +/- 4 vs -2 +/- 4%; p < .05). We conclude that the ANF response to saline infusion is delayed by ACE-inhibition in borderline hypertensives. The abnormalities observed in ANF response could follow the changes in peripheral venous distensibility and contribute to the pressor and neuro-humoral derangements described in borderline hypertensives during volume expansion.

Factors associated with acute salt-sensitivity in borderline hypertensive patients.

The acute sensitivity to sodium loading has been investigated in 26 borderline hypertensive patients (BHT) undergoing acute i.v. NaCl infusion. Measurements included blood pressure (BP), forearm vascular resistance (FVR) and venous distensibility (VV30), plasma renin activity (PRA), plasma aldosterone, plasma atrial natriuretic factor (ANF), and plasma levels of endogenous Na+/K+ATPase inhibitor. Sodium loading was associated with a greater than 8% increase in mean BP in 12 patients defined as salt-sensitive (NaCl-SENS) in comparison to salt-insensitive (NaCl-INSENS) subset. NaCl-SENS patients in comparison to NaCl-INSENS exhibited 1) a greater baseline VV30 (2.1 vs 1.4 ml/100 ml; p less than .005), and a response to saline characterized by 2) increased FVR (21.4 vs -6.5%; p less than .005), 3) blunted PRA suppression (-42 vs -67%; p less than .05), 4) delayed ANF response and 5) release of a Na+/K+ATPase inhibitor. Post-loading cumulative urinary sodium excretion was reduced in NaCl-SENS borderline hypertensives compared to NaCl-INSENS (2.6 vs 3.8 mumol/min/Kg; p less than .05). We conclude that acute salt-sensitivity in BHT is characterized by a blunted hormonal response to sodium loading which could be responsible of the activation of hemodynamic as well as humoral mechanisms leading to progressive blood pressure increase.