Evaluation of sulfate rhizofiltration by Carpobrotus chilensis for treating mining waters.

Chile, the world's leading copper producer, generates significant volumes of mining waters, some of which cannot be recirculated into the production process. These mining waters are characterized by elevated sulfate (SO42-) concentrations, requiring sustainable management strategies for potential reuse. This study aims to evaluate the rhizofiltration technique using Carpobrotus chilensis for treating mining waters with a high SO42- concentration. Initially, the mining waters exhibited a pH of 7.97 ± 0.16 and a SO42- concentration of 2,743 ± 137 mg L-1, while the control water had a pH of 7.88 ± 0.08 and a SO42- concentration of 775 ± 19.0 mg L-1. The plants were hydroponically cultivated in 40 L containers with mining waters and drinking water as a control. Over an 8-week period, the pH of the mining water decreased to 3.12 ± 0.01, and the SO42- concentration declined to 2,200 ± 110 mg L-1. Notably, the fresh weight of roots was significantly higher in plants grown in mining water (22.2 ± 6.66 g) compared to those in the control treatment (14.3 ± 4.28 g). However, an undesirable increase in the acidity was observed in the mining waters after rhizofiltration, which was attributed to hydrogen sulfate (HSO4-) and/or root exudates. Despite the unexpected increase in acidity, C. chilensis effectively reduced the concentration of SO42- in mining waters by 20%. Additionally, the C. chilensis roots accumulated 4.84 ± 1.40% of sulfur (S), a level comparable to thiophore plants. This study provides evidence that this non-aquatic plant can be used in sulfate rhizofiltration.

Caprobrotus chilensis is a good candidate for sulfate rhizolfiltration in mining waters.The accumulation of sulfur by the roots of Carpobrotus chilensis reached 4.84%Mining waters with a high concentration of sulfates require control of the redox potential.

El Niño resilience farming on the north coast of Peru.

El Niño-Southern Oscillation has been treated as a disruptor of environmental and socioeconomic equilibrium both in ancient times and in modern-day Peru. Recent work in the coastal desert plain, known as the Pampa de Mocan, challenges this view by demonstrating that prehispanic irrigation systems were designed to incorporate floods and convert them into productive waters. Archaeological investigations in this landscape reveal a 2,000-y history of floodwater farming embedded in conventional canal systems. Together with a pollen record recovered from a prehispanic well, these data suggest that the Pampa de Mocan was a flexible landscape, capable of taking advantage of El Niño floodwaters as well as river water. In sharp contrast to modern-day flood mitigation efforts, ancient farmers used floodwaters to develop otherwise marginal landscapes, such as the Pampa de Mocan, which in turn mitigated risk during El Niño years. These archaeological data speak to contemporary policy debates in the face of increasingly intense and frequent natural disasters and question whether El Niño Southern Oscillation events should be approached as a form of temporary disorder or as a form of periodic abundance.

Availability of copper in mine tailings with humic substance addition and uptake by Atriplex halimus.

The chemical characteristics of mine tailings, organic amendments (doses), and plants are the critical factors that must be evaluated and monitored to ensure the sustainability of phytostabilization. The aim of this study was to evaluate the mobility of copper (Cu) in mine tailings (MT) of the Zone Central of Chile to which commercial humic substances were added, examining their effect on the uptake of Atriplex halimus. Two commercial humic substances (HS1 and HS2) extracted from leonardite (highly oxidized lignite), of different pH and total organic carbon, were evaluated by adsorption curve for Cu. In columns, soluble Cu, pH, and electrical conductivity in leachates were evaluated for MT, MT + HS1, and MT + HS2, and HS1 and HS2 in doses of 120 mg kg-1. In pot assay, seeds were germinated directly in MT and cultivated for 140 days with the addition of HS2 in 120 and 240 mg kg-1. Mine tailing presents high concentration of Cu (2016 ± 223 mg kg-1, pH 6.3 ± 0.1). The results of sequential extraction indicate that Cu is associated with the sulfide fraction of low risk of mobility. The amount of Cu sorbed by HS1 was higher than that sorbed by HS2, and both humic substances showing better fit to the Freundlich than Langmuir model. Lixiviation of Cu was significantly lower in MT + HS1 (0.166 ± 0.043 mg kg-1) and MT + HS2 (0.157 ± 0.018 mg kg-1) than in MT (0.251 ± 0.052 mg kg-1). Copper concentration in plants reached 185.8 ± 37.8 mg kg-1 in the roots and 32.6 ± 7.4 mg kg-1 in the aerial parts cultivated in MT without effect of the humic substance addition in Cu uptake nor growth. Copper concentrations in the aerial parts were adjusted to sufficient or normal levels in plant. A good management of mine tailings through phytostabilization could consider an adequate mixture of humic substances (to avoid leaching of metals) and an organic amendment that provides essential nutrients and increases biomass generation.

Source investigation of two outbreaks of skin and soft tissue infection by Mycobacterium abscessus subsp. abscessus in Venezuela.

Outbreaks of soft tissue or skin infection due to non-tuberculous mycobacteria are reported frequently in scientific journals but in general the infection source in these outbreaks remains unknown. In Venezuela, in two distinct outbreaks, one after breast augmentation surgery and another after hydrolipoclasy therapy, 16 patients contracted a soft tissue infection due to Mycobacterium abscessus subsp. abscessus. Searching for the possible environmental infection sources in these outbreaks, initially the tap water (in the hydrolipoclasy therapy outbreak) and a surgical skin marker (in the breast implant surgery outbreak), were identified as the infection sources. Molecular typing of the strains with a variable number tandem repeat typing assay confirmed the tap water as the infection source but the molecular typing technique excluded the skin marker. We discuss the results and make a call for the implementation of stringent hygiene and disinfection guidelines for cosmetic procedures in Venezuela.

[Achievement of cardiovascular prevention goals, pharmacologic prescription and major cardiovascular events among patients with coronary disease]. / Logro de metas de prevención secundaria, prescripción farmacológica y eventos cardiovasculares mayores en pacientes con enfermedad coronaria.

BACKGROUND: Implementation of health programs to reduce cardiovascular risk, are needed for secondary prevention of cardiovascular diseases. AIM: To evalúate achievements of secondary prevention goals, pharmacologic prescription and major cardiovascular events in patients with coronary artery disease. MATERIAL AND METHODS: Patients who had a first event of acute coronary syndrome, angioplasty or revascularization surgery, between January 2008 and June 2010, were contacted for a clinical and laboratory evaluation between June and October 2011. RESULTS: Seven hundred and two medical records were reviewed and 245 eligible patients were identified. Of these, we assessed 202 patients aged 64 ± 10 years (70% males). Sixty seven percent had two or more cardiovascular risk factors. A goal of HDL cholesterol level over 40 mg/dL was achieved in 91 % of patients, smoking cessation in 84% and a total cholesterol < 200 mg/dL in 66%. A blood pressure below 130/85 mm Hg was achieved in 30% of patients, a normal BMI in 19% and LDL cholesterol levels below 70 mg/dL in 18%. At the moment of assessment, 87%> were using aspirin, 78%> statins, 74% angiotensin converting enzyme inhibitors or angiotensin II receptor antagonists and 66%o were using ß--blockers. Twenty two percent of patients had a major cardiovascular event during the follow up, which lasted 28 ± 8 months. CONCLUSIONS: A low percentage of cardiovascular goals achievement was observed in this sample of patients, with a high prevalence of overweight and obesity. A high percentage quit smoking after their first cardiovascular event. Despite the high percentage of drug prescription, hypertension and dyslipidemia were not fully controlled.

[Impact of the "daily huddle" on the safety of pediatric hospitalized patients]. / Impacto de los «daily huddle¼ en la seguridad del paciente pediátrico hospitalizado.

INTRODUCTION: In 2017, the Joint Commission proposed daily meetings called "huddle" as an indicator of quality of care. They are brief daily meetings of the multidisciplinary team, where security problems of the last 24h are shared and risks are anticipated. The objectives were to describe the most frequent safety events in Pediatric wards, implement improvements in patient safety, improve team communication, implement international safety protocols, and measure the satisfaction of the staff involved. MATERIAL AND METHODS: Prospective, longitudinal and analytical design (June 2020-February 2022), with previous educational intervention. Safety incidents, data related to unequivocal identification, allergy and pain records, data from the Scale for the Early Detection of Deficiencies (SAPI) and the Scale for the Secure Transmission of Information (SBAR) were collected. The degree of satisfaction of the professionals was evaluated. RESULTS: Three hundred forty-eight security incidents were recorded. Medication prescription or administration errors stood out (n=103). Drug prescription or administration errors stood out (n=103), especially those related to high-risk medication: acetaminophen (n=14) (×10 doses of acetaminophen; n=6), insulin (n=6), potassium (n=5) and morphic (n=5). An improvement was observed in the pain record; 5% versus 80% (P<.01), in the SAPI registry 5% versus 70% (P<.01), in SBAER scale 40% vs 100% (P<.01), in unequivocal identification of the patient 80% versus 100%; (P<.01) and in the application of analgesic techniques 60% versus 85% (P=.01). In the survey of professionals, a degree of satisfaction of 8 (7-9.5)/10 was obtained. CONCLUSIONS: Huddles made it possible to learn about security events in our environment and increase the safety of hospitalized patients, and improved communication and the relationship of the multidisciplinary team.

Cross-suppression of EGFR ligands amphiregulin and epiregulin and de-repression of FGFR3 signalling contribute to cetuximab resistance in wild-type KRAS tumour cells.

BACKGROUND: In addition to the mutational status of KRAS, the epidermal growth factor receptor (EGFR) ligands amphiregulin (AREG) and epiregulin (EREG) might function as bona fide biomarkers of cetuximab (Ctx) sensitivity for most EGFR-driven carcinomas. METHODS: Lentivirus-delivered small hairpin RNAs were employed to specifically reduce AREG or EREG gene expression in wild-type KRAS A431 squamous cell carcinoma cells. Colony-forming assays were used to monitor the impact of AREG and EREG knockdown on Ctx efficacy. Amphiregulin and EREG protein expression levels were assessed by quantitative ELISA in parental A431 cells and in pooled populations of A431 cells adapted to grow in the presence of Ctx. A phosphoproteomic platform was used to measure the relative level of phosphorylation of 42 distinct receptor tyrosine kinases before and after the acquisition of resistance to Ctx. RESULTS: Stable gene silencing of either ligand was found to notably reduce the expression of the other ligand. Parental A431 cells with normal expression levels of AREG/EREG exhibited significantly increased growth inhibition in response to Ctx, compared with derivatives that are engineered to produce minimal AREG/EREG. The parental A431 cells acutely treated with Ctx exhibited reduced basal expression levels of AREG/EREG. Pooled populations of Ctx-resistant A431 cells expressed significantly lower levels of AREG/EREG and were insensitive to the downregulatory effects of Ctx. Phosphoproteomic screen identified a remarkable hyperactivation of FGFR3 in Ctx-resistant A431 cells, which gained sensitivity to the cytotoxic and apoptotic effects of the FGFR3 TK inhibitor PD173074. The A431 parental cells acutely treated with Ctx rapidly activated FGFR3 and their concomitant exposure to Ctx and PD173074 resulted in synergistic apoptosis. CONCLUSION: Cross-suppression of AREG/EREG expression may explain the tight co-expression of AREG and EREG, as well as their tendency to be more highly expressed than other EGFR ligands to determine Ctx efficacy. The positive selection for Ctx-resistant tumour cells exhibiting AREG/EREG cross-suppression may have an important role in the emergence of Ctx resistance. As de-repression of FGFR3 activity rapidly replaces the loss of EGFR-ligand signalling in terms of cell proliferation and survival, combinations of Ctx and FGFR3-targeted drugs may be a valuable strategy to enhance the efficacy of single Ctx while preventing or delaying acquired resistance to Ctx.

The rs1800795 single nucleotide polymorphism in the IL6 gene is not associated with primary open angle glaucoma in Mexican population.

PURPOSE: Interleukin-6 (IL-6) is a proinflammatory cytokine with pleiotropic effects which has been related to primary open angle glaucoma (POAG) due to its particular effect of protecting the retinal ganglion cells (RGc) from the apoptosis. Different single nucleotide polymorphisms (SNP) have been associated with POAG. The aim of this study was to determine whether an association between IL-6 rs1800795 (-174 G>C) SNP and a higher risk for POAG is present in western Mexican population. METHODS: One hundred and sixty-five unrelated Mexican mestizo patients with POAG and 108 control subjects were included. Genomic DNA was extracted from leukocytes and purified, followed by genotyping and amplification by polymerase chain reaction (PCR) with Taqman Biosystem probes. Allelic and genotypic diversity was evaluated between cases and control subjects. RESULTS: There was no statistically significant association between allele and genotype frequencies, neither with dominant nor recessive genetic association models (p > 0.05). CONCLUSION: Even though there is a role of IL6 in the pathophysiology of POAG, our results ruled out the association between IL-6 and the rs1800795 SNP showing not to be an index of higher risk for POAG in Mexican population.

Monocyte Locomotion Inhibitory Factor confers neuroprotection and prevents the development of murine cerebral malaria.

Cerebral malaria (CM) is a neurological complication derived from the Plasmodium falciparum infection in humans. The mechanisms involved in the disease progression are still not fully understood, but both the sequestration of infected red blood cells (iRBC) and leukocytes and an exacerbated host inflammatory immune response are significant factors. In this study, we investigated the effect of Monocyte Locomotion Inhibitory Factor (MLIF), an anti-inflammatory peptide, in a well-characterized murine model of CM. Our data showed that the administration of MLIF increased the survival and avoided the neurological signs of CM in Plasmodium berghei ANKA (PbA) infected C57BL/6 mice. MLIF administration down-regulated systemic inflammatory mediators such as IFN-γ, TNF-α, IL-6, CXCL2, and CCL2, as well as the in situ expression of TNF-α in the brain. In the same way, MLIF reduced the expression of CD31, CD36, CD54, and CD106 in the cerebral endothelium of infected animals and prevented the sequestration of iRBC and leucocytes in the brain microvasculature. Furthermore, MLIF inhibited the activation of astrocytes and microglia and preserved the integrity of the blood-brain barrier (BBB). In conclusion, our results demonstrated that the administration of MLIF increased survival and conferred neuroprotection by decreasing neuroinflammation in murine CM.

[Haemorrhagic posterior reversible encephalopathy syndrome and COVID-19]. / Síndrome de encefalopatía posterior reversible hemorrágica y COVID-19.

TITLE: Síndrome de encefalopatía posterior reversible hemorrágica y COVID-19.

Evaluación de la efectividad del Triclabendazol como fasciolicida en caprinos de la provincia de Neuquén, Argentina / Evaluation of the efficacy of Triclabendazol to treat liver worm in goats in Nequen province, Argentina

Resumen Debido al uso frecuente del triclabendazol (TCBZ) por parte de los productores, sumado al reporte reciente de resistencia de Fasciolahepatica al fármaco detectada en rodeos y majadas de Neuquén, se llevó a cabo el presente trabajo con el objetivo de evaluar la eficacia del TCBZ como fasciolicida en caprinos bajo un sistema de producción trashumante del norte de la provincia de Neuquén, Argentina. La eficacia se evaluó mediante un test de reducción de conteo de huevos de F. hepatica en caprinos Criollo Neuquino parasitados naturalmente. Se utilizaron dos grupos de animales: un Grupo Control (n: 10) que no recibió tratamiento y un Grupo Tratado (n: 10) al que se le administró TCBZ al 10% (Biofasiolex T10-Biogénesis Bagó ®) vía oral a dosis de 10 mg/kg PV. Al día 0 y 21 post tratamiento, se tomaron muestras de materia fecal para análisis coproparasitológicos. Se evidenció una reducción del conteo de huevos de F. hepatica del 100%, indicando el mantenimiento de la eficacia del fasciolicida en los caprinos evaluados. Se discuten los alcances del uso del test de reducción de conteo de huevos en zonas con producción trashumante del ganado.

Abstract Because of the frequent use of triclabendazole TCBZ by farmers and the recent reports of Fasciola hepatica resistance to this drug in herds and flocks from Neuquén, we carried out this study with the aim to evaluate the efficacy of TCBZ as fasciolicide in goats under a transhumance system from northern of Neuquén, Argentina. A fecal egg count reduction test (FECRT) was performed on Creale Neuquino goats naturally parasitized with F. hepatica. Twenty goats were divided into two groups: A control group (n: 10) which was left untreated, and a treatment group (n: 10) that was dosed orally with TCBZ 10% (Biofasiolex T10-Biogénesis Bagó ®). On Day 0 and Day 21 post-treatment, fecal samples were taken and analyzed by coproscopical examination. According to the FECRT, drug efficacy was 100 % and confirms that TCBZ maintains its efficacy against F. hepatica on goats. The usefulness of the FECRT in these zones under transhumance livestock production is discussed.

[Association between moderate-severe bronchiolitis and syndrome of inappropriate antidiuretic hormone secretion in emergency departments]. / Asociación entre bronquiolitis moderada-grave y síndrome de secreción inadecuada de hormona antidiurética en urgencias.

OBJECTIVES: To identify clinical characteristics that may lead to the early recognition of patients admitted to the hospital for moderate-to-severe bronchiolitis with urine results associated with the syndrome of inappropriate antidiuretic hormone secretion (SIADH). PATIENTS AND METHODS: A prospective observational study was conducted, spanning the bronchiolitis epidemic season (October 2012-March 2013), including all children who were admitted to the hospital with a diagnosis of moderate-to-severe bronchiolitis. The following criteria were used to establish a diagnosis of SIADH: urine sodium level of 40 mmol/L or greater, urine osmolarity above 500 mosm/Kg, and urine density of 1020 g/L or greater. Demographic characteristics, ventilation mode and clinical outcome were also analyzed. A comparison was made between those patients that met urine SIADH criteria and those who did not. RESULTS: A total of 126 children were included, and 23 (18.6%) of them had urine SIADH criteria. Patients in this group had a higher incidence of pneumonia and/or atelectasis on chest X-Ray (21.7% vs. 1.9%, P=.002), worse response to bronchodilator treatment with nebulized adrenaline (69,5% vs. 28,1%, P=.016), more need for respiratory assistance (high flow oxygen therapy (17.4% vs. 7.7%, p=.016), or non-invasive mechanical ventilation (13% vs. 5.8%, P=.034), and more admissions to the PICU (26.1% vs. 6.8%, P=.007). CONCLUSIONS: Patients older than one month with acute moderate bronchiolitis and urine SIADH criteria have worse clinical courses and more need for non-invasive mechanical ventilation, PICU admission, and have a higher incidence of pneumonia on chest X-ray. For that reason, it is recommended to collect a urine sample from these patients to allow an early diagnosis of SIADH, and thus early treatment of fluid and electrolyte abnormalities.

Characterization of non-dominant lethal mutations in the yeast plasma membrane H+-ATPase gene.

Site-directed mutants of yeast ATPase were previously studied after introduction of mutant alleles into a yeast strain where these alleles were constitutively expressed while the expression of the wild-type chromosomal ATPase gene was turned off. As a functional H+ pump is essential, strong selective pressure leads to the accumulation of revertants during growth of cells harboring variants with low activity. Thus, constitutive expression of the mutant gene can select phenotypes which reflect events such as gene conversion or reversion. We have therefore re-evaluated the phenotypes of non-dominant lethal alleles in an alternative set of conditional expression systems. We show that eight of 11 previously described site-directed mutations behave as recessive lethal alleles.

[Sudden paralysis of upward gaze in a 9-year-old girl]. / Parálisis súbita de la supraversión de la mirada en una niña de 9 años.

TITLE: Parálisis súbita de la supraversión de la mirada en una niña de 9 años.

[Evolution of non-invasive ventilation in acute bronchiolitis]. / Evolución de la ventilación mecánica no invasiva en la bronquiolitis.

OBJECTIVES: The aim of the study was to analyse the evolution, over a12-year period, of the use of non-invasive (NIV) and invasive ventilation (IV) in children admitted to a Paediatric Intensive Care Unit (PICU) due to acute bronchiolitis. PATIENTS AND METHODS: A retrospective observational study was performed including all children who were admitted to the PICU requiring NIV or IV between 2001 and 2012. Demographic characteristics, ventilation assistance and clinical outcome were analysed. A comparison was made between the first six years and the last 6 years of the study. RESULTS: A total of 196 children were included; 30.1% of the subjects required IV and 93.3% required NIV. The median duration of IV was 9.5 days and NIV duration was 3 days. The median PICU length of stay was 7 days, and 2% of the patients died. The use of NIV increased from 79.4% in first period to 100% in the second period (P<.0001) and IV use decreased from 46% in first period to 22.6% in the last 6 years (P<.0001). Continuous positive airway pressure and nasopharyngeal tube were the most frequently used modality and interface, although the use of bi-level non-invasive ventilation (P<.001) and of nasal cannulas significantly increased (P<.0001) in the second period, and the PICU length of stay was shorter (P=.011). CONCLUSION: The increasing use of NIV in bronchiolitis in our PICU during the last 12 years was associated with a decrease in the use of IV and length of stay in the PICU.

Efficacy comparison of oral rehydration solutions containing either 90 or 75 millimoles of sodium per liter.

In a randomized trial, 62 infants 2 to 35 months of age with dehydration due to acute watery diarrhea were allocated to one of two groups: group A received solution A (World Health Organization-recommended oral rehydration solution), which contained (mmol/L): Na+ 90, K+ 20, Cl- 80, citrate3- 10, and glucose 110; group B received solution B (Pedialyte RS; Abbott Laboratories, North Chicago), which contained (in mmol/L): Na+ 75, K+ 20, Cl- 65, citrate3- 10, and glucose 139. Oral therapy was given until clinical signs of hydration status were normal. During the 48-hour trial, the following laboratory data were collected: blood gases, serum electrolytes, glucose, urea, and creatinine values and sodium and potassium concentrations in stool and urine; serial weights and clinical signs were also reported. Six of the 62 infants, three in each group, required intravenous fluids because of high stool output. Results of clinical outcome and normalization of altered serum electrolyte values were similar in both groups. During the 48-hour trial, eight patients in group A and four in group B had mild, asymptomatic hypernatremia. Pedialyte RS was found to be a safe glucose/electrolyte solution for oral rehydration therapy.

Transplantation of human fetal retinal pigment epithelium rescues photoreceptor cells from degeneration in the Royal College of Surgeons rat retina.

PURPOSE: The Royal College of Surgeons (RCS) rat suffers from a well-characterized, early-onset, and relentless form of photoreceptor cell degeneration. It has been shown that allografts of retinal pigment epithelial cells from normal perinatal rats have rescue effects in this condition. In preparation for human application, the authors determined whether human fetal retinal pigment epithelium (RPE) grafts have a photoreceptor rescue effect in RCS dystrophic rat retinas. METHODS: Sheets of RPE from human fetal eyes (10 to 16 weeks gestational age) were isolated according to the authors' recently described method. Fragments of the RPE sheets were transplanted to the subretinal space within the superior hemisphere. Transplants were performed within the superior equatorial region of five dystrophic RCS rats, one eye per animal. A similar volume of vehicle was injected into the subretinal space of five age-matched control rats, again one eye per rat. All rats were immunosuppressed with daily injections of cyclosporine. Using light microscopy, photoreceptor cell nuclear profiles of superior equatorial (SE) and inferior equatorial (IE) regions of transplanted and sham-injected control animals were counted. RESULTS: Four weeks after transplantation, a dramatic rescue effect was observed. Microscopically, presumptive donor RPE cells were seen as single pigmented cells and as cell clusters in the subretinal space. An outer nuclear layer three to four profiles thick was present in the area of the RPE transplant but was nearly absent in the rest of the retina, as well as in the retinas of control rats. The number of photoreceptor nuclear profiles per 100 microns was 34.7 +/- 2.2 (mean +/- SEM) in the SE region of transplanted rats and 3.5 +/- 1.4 in the same region of sham-injected rats. There were 3.0 +/- 1.0 photoreceptor nuclear profiles in the IE region of transplanted rats and 3.5 +/- 1.2 in the IE region of sham-injected eyes. No evidence of graft rejection was seen. CONCLUSIONS: This study provides the first indication that transplanted human fetal RPE cells are able to rescue photoreceptor cells in a model of hereditary retinal degeneration.

Age-related weakening of baroreflex-mediated sympathetic activity in spontaneously hypertensive rats in response to blood pressure reduction.

Nicardipine, a dihydropyridine type calcium channel blocker, was infused into 4-, 6-, and 23-wk-old spontaneously hypertensive (SH) and age-matched normotensive Wistar-Kyoto (WKY) rats (under sodium thiobutabarbital anesthesia and ventilation, n = 4) through the left femoral vein, resulting in the reduction of blood pressure. In each rat, mean arterial blood pressure, heart rate, and the concentration of plasma catecholamines (CAs), norepinephrine (NE), and epinephrine (E) were concomitantly determined, and the correlations between these three variables were studied. During the infusion of nicardipine, the plasma concentration of CAs was measured with an automatic detection system in blood samples collected from the right femoral artery of each rat. The reduction in blood pressure induced by nicardipine brought about an increase in plasma CA levels. The blood pressure correlated well with the logarithm of plasma NE or E concentration according to the formula Y= -alpha log (X) + m (Y, blood pressure; X, concentration of plasma NE or E; a, slope; and m, intercept). The slopes (as) of 6-wk-old and 23-wk-old SH rats were significantly greater than those of aged-matched WKY rats, meaning that the increment in plasma CAs in response to a decrease in blood pressure was smaller in SH than in WKY rats of similar ages. However, no significant differences were found between the as of 4-wk-old SH and WKY rats. We conclude that the increment in the baroreflex-mediated sympathetic activity in response to a drop in blood pressure induced by nicardipine is similar or greater in prehypertensive SH than in normotensive WKY 4-wk-old rats, while the increment becomes smaller in SH rats with the onset of hypertension (6-wk-old rats), and is much less in fully hypertensive adult (23-wk-old) SH rats than in age-matched WKY rats. On the basis of these findings and previous data obtained by neurography, we conclude that plasma CAs can be used to evaluate baroreflex-mediated sympathetic activity countering the blood pressure reduction caused by calcium antagonists.