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1.
Molecules ; 26(11)2021 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-34205850

RESUMO

Left untreated, nonalcoholic fatty liver disease can progress to nonalcoholic steatohepatitis (NASH), fibrosis, and end-stage liver disease. To date, few if any therapies have proven effective against NASH with fibrosis. Quantification and qualification of hepatic scar might enable development of more effective targeted therapies. In a murine model of NASH induced by diet, we characterized fibrillar collagen deposition within the hepatic parenchyma. At harvest, livers from the modified diet cohort exhibited NASH with fibrosis. Transcriptomic analysis of hepatic tissue revealed increased col1a1, col1a2, and col3a1, each of which correlated directly with hepatic hydroxyproline content. Circular polarized microscopic analysis of Picrosirius red-stained liver sections revealed deposition of collagen type I within the parenchyma. Development of therapeutics designed to mitigate collagen type I accumulation might prove effective in NASH with fibrosis.


Assuntos
Colágeno Tipo III/genética , Colágeno Tipo I/genética , Colágeno/metabolismo , Fast Foods/efeitos adversos , Hepatopatia Gordurosa não Alcoólica/metabolismo , Animais , Estudos de Casos e Controles , Colágeno/genética , Cadeia alfa 1 do Colágeno Tipo I , Modelos Animais de Doenças , Feminino , Perfilação da Expressão Gênica , Regulação da Expressão Gênica/efeitos dos fármacos , Fígado/efeitos dos fármacos , Fígado/metabolismo , Masculino , Camundongos , Microscopia de Polarização , Hepatopatia Gordurosa não Alcoólica/induzido quimicamente , Hepatopatia Gordurosa não Alcoólica/genética , Regulação para Cima
2.
Molecules ; 23(9)2018 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-30231499

RESUMO

The practice of medicine is ever evolving. Diagnosing disease, which is often the first step in a cure, has seen a sea change from the discerning hands of the neighborhood physician to the use of sophisticated machines to use of information gleaned from biomarkers obtained by the most minimally invasive of means. The last 100 or so years have borne witness to the enormous success story of allopathy, a practice that found favor over earlier practices of medical purgatory and homeopathy. Nevertheless, failures of this approach coupled with the omics and bioinformatics revolution spurred precision medicine, a platform wherein the molecular profile of an individual patient drives the selection of therapy. Indeed, precision medicine-based therapies that first found their place in oncology are rapidly finding uses in autoimmune, renal and other diseases. More recently a new renaissance that is shaping everyday life is making its way into healthcare. Drug discovery and medicine that started with Ayurveda in India are now benefiting from an altogether different artificial intelligence (AI)-one which is automating the invention of new chemical entities and the mining of large databases in health-privacy-protected vaults. Indeed, disciplines as diverse as language, neurophysiology, chemistry, toxicology, biostatistics, medicine and computing have come together to harness algorithms based on transfer learning and recurrent neural networks to design novel drug candidates, a priori inform on their safety, metabolism and clearance, and engineer their delivery but only on demand, all the while cataloging and comparing omics signatures across traditionally classified diseases to enable basket treatment strategies. This review highlights inroads made and being made in directed-drug design and molecular therapy.


Assuntos
Aprendizado Profundo , Descoberta de Drogas , Medicina de Precisão , Inteligência Artificial , Desenho de Fármacos , Reposicionamento de Medicamentos , Redes Neurais de Computação , Sistemas Automatizados de Assistência Junto ao Leito
3.
Am J Physiol Renal Physiol ; 311(2): F352-61, 2016 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-27252491

RESUMO

Ischemia-reperfusion-mediated acute kidney injury can necessitate renal replacement therapy and is a major cause of morbidity and mortality. We have identified BB3, a small molecule, which when first administered at 24 h after renal ischemia in rats, improved survival, augmented urine output, and reduced the increase in serum creatinine and blood urea nitrogen. Compared with control kidneys, the kidneys of BB3-treated animals exhibited reduced levels of kidney injury molecule-1, neutrophil gelatinase-associated lipocalin, and reduced tubular apoptosis and acute tubular necrosis but enhanced tubular regeneration. Consistent with its hepatocyte growth factor-like mode of action, BB3 treatment promoted phosphorylation of renal cMet and Akt and upregulated renal expression of the survival protein Bcl-2. These data suggest that the kidney is amenable to pharmacotherapy even 24 h after ischemia-reperfusion and that activation of the hepatocyte growth factor signaling pathway with the small molecule BB3 confers interventional benefits late into ischemia-reperfusion injury. These data formed, in part, the basis for the use of BB3 in a clinical trial in kidney recipients presenting with delayed graft function.


Assuntos
Injúria Renal Aguda/prevenção & controle , Traumatismo por Reperfusão/prevenção & controle , Injúria Renal Aguda/patologia , Animais , Apoptose , Fator de Crescimento de Hepatócito/metabolismo , Túbulos Renais/patologia , Masculino , Ratos , Ratos Sprague-Dawley , Regeneração/efeitos dos fármacos , Traumatismo por Reperfusão/patologia
4.
Toxics ; 11(6)2023 Jun 08.
Artigo em Inglês | MEDLINE | ID: mdl-37368615

RESUMO

Industrial areas play an important role in the urban ecosystem. Industrial site environmental quality is linked to human health. Soil samples from two different cities in India, Jamshedpur and Amravati, were collected and analyzed to assess the sources of polycyclic aromatic hydrocarbons (PAHs) in industrial areas and their potential health risks. The total concentration of 16 PAHs in JSR (Jamshedpur) varied from 1662.90 to 10,879.20 ng/g, whereas the concentration ranged from 1456.22 to 5403.45 ng/g in the soil of AMT (Amravati). The PAHs in the samples were dominated by four-ring PAHs, followed by five-ring PAHs, and a small percentage of two-ring PAHs. The ILCR (incremental lifetime cancer risk) of the soil of Amravati was lower compared to that of Jamshedpur. The risk due to PAH exposure for children and adults was reported to be in the order of ingestion > dermal contact > inhalation while for adolescents it was dermal contact > ingestion > inhalation in Jamshedpur. In contrast, in the soil of Amravati, the PAH exposure path risk for children and adolescents were the same and showed the following order: dermal contact > ingestion > inhalation while for the adulthood age group, the order was ingestion > dermal contact > inhalation. The diagnostic ratio approach was used to assess the sources of PAHs in various environmental media. The PAH sources were mainly dominated by coal and petroleum/oil combustion. As both the study areas belong to industrial sites, the significant sources were industrial emissions, followed by traffic emissions, coal combustion for domestic livelihood, as well as due to the geographical location of the sampling sites. The results of this investigation provide novel information for contamination evaluation and human health risk assessment in PAH-contaminated sites in India.

5.
Front Med (Lausanne) ; 9: 1062890, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36619635

RESUMO

Selected renal cells (SRCs), a renal epithelial cell-enriched platform, are being advanced as an autologous cell-based therapy for the treatment of chronic kidney disease. However, the mechanism underlying its renal reparative and restorative effects remains to be fully elucidated. In this study, we coupled knowledgebase data with empirical findings to demonstrate that genes differentially expressed by SRCs form interactomes within tubules and glomeruli and mediate a suite of renal developmental activities including epithelial cell differentiation, renal vasculature development, and glomerular and nephron development. In culture, SRCs form organoids which self-assemble into tubules in the presence of a scaffold. Implanted into the kidneys of subtotally nephrectomized rats, SRCs are associated with comma- and S-shaped body cell formation and glomerular development, and improvement in renal filtration indices and renal microarchitecture. These data suggest that SRCs harbor nephrogenic potential, which may explain, at least in part, their therapeutic activity.

6.
Mol Omics ; 17(6): 911-916, 2021 12 06.
Artigo em Inglês | MEDLINE | ID: mdl-34757352

RESUMO

Emerging evidence suggests that microRNA dysregulation plays an important role in nonalcoholic steatohepatitis. Using a model of diet-induced liver disease that progresses to fibrosis and hepatocellular carcinoma, we identify a set of 22 microRNA with robust correlation with liver enzyme levels and liver collagen content. These disease-asssociated miRs play pivotal roles in steatosis, extracellular matrix deposition and liver cancer, and may form the basis for identification of therapeutic strategies against this form of liver disease.


Assuntos
Neoplasias Hepáticas , MicroRNAs , Hepatopatia Gordurosa não Alcoólica , Animais , Dieta , Modelos Animais de Doenças , Humanos , Neoplasias Hepáticas/genética , Camundongos Endogâmicos C57BL , MicroRNAs/genética , Hepatopatia Gordurosa não Alcoólica/genética
7.
ACS Omega ; 5(29): 18465-18471, 2020 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-32743224

RESUMO

Left untreated nonalcoholic fatty liver disease (NAFLD) can progress to nonalcoholic steatohepatitis (NASH), fibrosis, cirrhosis, and hepatocellular carcinoma. The observed failure of clinical trials in NASH may suggest that current model systems do not fully recapitulate human disease, and/or hallmark pathological features of NASH may not be driven by the same pathway in every animal model let alone in each patient. Identification of a model-agnostic disease-associated node can spur the development of effective drugs for the treatment of liver disease. Glycerol-3-phosphate acyltransferase1 (GPAT1) plays a pivotal role in lipid accumulation by shunting fats away from oxidation. In the present study, hepatic GPAT1 expression was evaluated in three etiologically different models of NAFLD. Compared to the sham cohort, hepatic GPAT1 mRNA levels were elevated by ∼5-fold in steatosis and NASH with fibrosis with immunofluorescent staining revealing increased GPAT1 in the fatty liver. A significant and direct correlation (r = 0.88) was observed between hepatic GPAT1 mRNA expression and severity of the liver disease. Picrosirius red staining revealed a logarithmic relation between hepatic GPAT1 mRNA expression and scar. These data suggest that hepatic GPAT1 is an early disease-associated model-agnostic node in NAFLD and form the basis for the development of a potentially successful therapeutic against NASH.

8.
Diagnostics (Basel) ; 10(10)2020 Oct 04.
Artigo em Inglês | MEDLINE | ID: mdl-33020436

RESUMO

There is increasing evidence that nonalcoholic steatohepatitis (NASH) is a risk factor for hepatocellular carcinoma (HCC) in the absence of cirrhosis, a phenomenon termed noncirrhotic HCC. Early diagnosis of HCC is critical to a favorable prognosis. We tested the hypothesis that hydroxyproline content of liver biopsy samples is diagnostic for HCC in murine models of NASH induced by diet or by diet and chemicals. The training set comprised mice fed a standard diet or a fast-food diet with or without administration of thioacetamide. At harvest, livers from the modified diet cohort exhibited NASH with a subset of NASH livers exhibiting HCC. Hydroxyproline content was measured in liver biopsy samples with tissue in the NASH+HCC cohort sampled from the remote, nontumor parenchyma. Plotting the receiver operating characteristics (ROC) with hydroxyproline as the continuous variable against the absence or presence of HCC yielded an area under ROC of 0.87, a threshold of >0.18 µg hydroxyproline/mg liver and sensitivity of 91% with a specificity of 83.3%. The use of liver hydroxyproline content as a diagnostic for HCC in a test set comprising healthy, NASH and NASH+HCC livers proved 87% accurate.

9.
Med Sci (Basel) ; 7(4)2019 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-30939854

RESUMO

Caroli syndrome, characterized by saccular dilatation of intrahepatic ducts and congenital hepatic fibrosis, is without therapy in part due to its ultra-rare prevalence and the apparent lack of availability of a suitable experimental model. While the PCK rat has long been used as a model of fibropolycystic kidney disease, hepatobiliary biophysics in this animal model is incompletely characterized. Compared to age-matched, wild-type controls, the PCK rat demonstrated severe hepatomegaly and large saccular dilated intrahepatic ducts. Nevertheless, hepatic density was greater in the PCK rat, likely due to severe duct wall sclerosis accompanied by scarring across the hepatic parenchyma. Extracellular matrix accumulation appeared proportional to duct cross-sectional area and liver volume and appeared compensatory in nature. The PCK rat livers exhibited both cholangiocarcinoma and hepatocellular carcinoma coincident with areas of increased extracellular matrix deposition. Together, these data suggest that the PCK rat model mimics at least in part the spectrum of hepatobiliary pathology observed in Caroli syndrome and highlights the attendant risk associated with this disease.

10.
Int J Appl Comput Math ; 4(5): 118, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-32289048

RESUMO

Measles and influenza are two major diseases-caused an epidemic in India. Therefore, in this paper, a SVEIRS epidemic mathematical model for measles and influenza is proposed and analyzed, where pre and post vaccinations are considered as control strategies with waning natural, vaccine-induced immunity and saturation incidence rate. The dissection of the proposed model is conferred in terms of the associated reproduction number R v , which is determined by the next-generation approach and obtained that if R v ≤ 1 , the disease-free equilibrium exists and it is locally as well as globally asymptotically stable. Further for R v > 1 , a unique endemic equilibrium exists and it is also locally as well as globally asymptotically stable under certain conditions, which shows the prevalence and persistence of the disease in the population.

11.
World J Nephrol ; 7(5): 96-107, 2018 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-30211028

RESUMO

AIM: To evaluate the novel platelet-derived growth factor receptor and vascular endothelial growth factor receptor dual kinase inhibitor ANG3070 in a polycystic kidney disease-congenital hepatic fibrosis model. METHODS: At 6 wk of age, PCK rats were randomized to vehicle or ANG3070 for 4 wk. At 10 wk, 24 h urine and left kidneys were collected and rats were continued on treatment for 4 wk. At 14 wk, 24 h urine was collected, rats were sacrificed, and liver and right kidneys were collected for histological evaluation. For Western blot studies, PCK rats were treated with vehicle or ANG3070 for 7 d and sacrificed approximately 30 min after the last treatments. RESULTS: Compared to the wild-type cohort, the PCK kidney (Vehicle cohort) exhibited a marked increase in kidney and liver mass, hepato-renal cystic volume, hepato-renal fibrosis and hepato-renal injury biomarkers. Intervention with ANG3070 in PCK rats decreased kidney weight, reduced renal cystic volume and reduced total kidney hydroxyproline, indicating significantly reduced rental interstitial fibrosis compared to the PCK-Vehicle cohort. ANG3070 treatment also mitigated several markers of kidney injury, including urinary neutrophil gelatinase-associated lipocalin, kidney injury molecule-1, cystatin C and interleukin-18 levels. In addition, this treatment attenuated key indices of renal dysfunction, including proteinuria, albuminuria and serum blood urea nitrogen and creatinine, and significantly improved renal function compared to the PCK-Vehicle cohort. ANG3070 treatment also significantly decreased liver enlargement, hepatic lesions, and liver fibrosis, and mitigated liver dysfunction compared to the PCK-Vehicle cohort. CONCLUSION: These results suggest that ANG3070 has the potential to slow disease, and may serve as a bridge toward hepato-renal transplantation in patients with fibropolycystic disease.

12.
PLoS One ; 13(1): e0190815, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29351309

RESUMO

The extent of scarring or renal interstitial collagen deposition in chronic kidney disease (CKD) can only be ascertained by highly invasive, painful and sometimes risky, tissue biopsy. Interestingly, while CKD-related abnormalities in kidney size can often be visualized using ultrasound, not only does the ellipsoid formula used today underestimate true renal size, but the calculated renal size does not inform tubulointerstitial collagen content. We used coronal kidney sections from healthy mice and mice with kidney disease to develop a new formula for estimating renal parenchymal area. While treating the kidney as an ellipse with the major axis (a) the polar distance, this technique involves extending the minor axis (b) into the renal pelvis to obtain a new minor axis, be. The calculated renal parenchymal area is remarkably similar to the true or measured area. Biochemically determined kidney collagen content revealed a strong and positive correlation with the calculated renal parenchymal area. Picrosirius red staining for tubulointerstitial collagen also correlated with calculated renal parenchymal area. The extent of renal scarring, i.e. kidney interstitial collagen content, can now be computed by making just two axial measurements which can easily be accomplished via noninvasive imaging of this organ.


Assuntos
Colágeno/metabolismo , Rim/metabolismo , Insuficiência Renal Crônica/metabolismo , Animais , Compostos Azo , Corantes , Modelos Animais de Doenças , Fibrose , Humanos , Rim/diagnóstico por imagem , Rim/patologia , Masculino , Camundongos , Modelos Biológicos , Tamanho do Órgão , Insuficiência Renal Crônica/diagnóstico por imagem , Insuficiência Renal Crônica/patologia
13.
PLoS One ; 13(6): e0198937, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29944670

RESUMO

Although cirrhosis is a key risk factor for the development of hepatocellular carcinoma (HCC), mounting evidence indicates that in a subset of patients presenting with non-alcoholic steatohepatitis (NASH) HCC manifests in the absence of cirrhosis. Given the sheer size of the ongoing non-alcoholic fatty liver disease (NAFLD) epidemic and the dismal prognosis associated with late-stage primary liver cancer there is an urgent need for HCC surveillance in the NASH population. Using serum levels of HCC biomarkers as vectors and biopsy-proven HCC or no HCC as outputs / binary classifier, a supervised learning campaign was undertaken to develop a minimally invasive technique for making a diagnosis of HCC in a clinically relevant model of NASH. Adult mice randomized to control diet or a fast food diet (FFD) were followed for up to 14 mo and serum level of a panel of HCC-relevant biomarkers was compared with liver biopsies at 3 and 14 mo. Both NAFLD Activity Score (NAS) and hepatic hydroxyproline content were elevated at 3 and 14 mo on FFD. Picrosirius red staining of liver sections revealed a filigree pattern of fibrillar collagen deposition with no cirrhosis at 14 mo on FFD. Nevertheless, 46% of animals bore one or more tumors on their livers confirmed as HCC in hematoxylin-eosin-stained liver sections. In this training set, receiver operating characteristic (ROC) curves analysis for serum levels of the HCC biomarkers osteopontin (OPN), alpha-fetoprotein (AFP) and Dickkopf-1 (DKK1) returned concordance-statistic/area under ROC curve of ≥ 0.89. Serum levels of OPN (threshold, 218 ng/mL; sensitivity, 82%; specificity, 86%), AFP (136 ng/mL; 91%; 97%) and DKK1 (2.4 ng/mL; 82%; 81%) diagnostic for HCC were confirmed in a test set comprising mice on control diet or FFD and mice subjected to hepatic ischemia-reperfusion injury. These data suggest that levels of circulating OPN, AFP and DKK1 can be used to make a diagnosis of HCC in a clinically relevant model of NASH.


Assuntos
Carcinoma Hepatocelular/sangue , Neoplasias Hepáticas/sangue , Fígado/patologia , Hepatopatia Gordurosa não Alcoólica/sangue , Animais , Biomarcadores Tumorais/sangue , Carcinoma Hepatocelular/diagnóstico , Carcinoma Hepatocelular/patologia , Modelos Animais de Doenças , Humanos , Neoplasias Hepáticas/diagnóstico , Neoplasias Hepáticas/patologia , Masculino , Camundongos Endogâmicos C57BL , Hepatopatia Gordurosa não Alcoólica/diagnóstico , Hepatopatia Gordurosa não Alcoólica/patologia , Aprendizado de Máquina Supervisionado
14.
World J Gastroenterol ; 23(23): 4181-4190, 2017 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-28694658

RESUMO

AIM: To evaluate a calcium activated potassium channel (KCa3.1) inhibitor attenuates liver disease in models of non-alcoholic fatty liver disease (NAFLD). METHODS: We have performed a series of in vitro and in vivo studies using the KCa3.1 channel inhibitor, Senicapoc. Efficacy studies of Senicapoc were conducted in toxin-, thioacetamide (TAA) and high fat diet (HFD)-induced models of liver fibrosis in rats. Efficacy and pharmacodynamic effects of Senicapoc was determined through biomarkers of apoptosis, inflammation, steatosis and fibrosis. RESULTS: Upregulation of KCa3.1 expression was recorded in TAA-induced and high fat diet-induced liver disease. Treatment with Senicapoc decreased palmitic acid-driven HepG2 cell death. (P < 0.05 vs control) supporting the finding that Senicapoc reduces lipid-driven apoptosis in HepG2 cell cultures. In animals fed a HFD for 6 wk, co-treatment with Senicapoc, (1) reduced non-alcoholic fatty liver disease (NAFLD) activity score (NAS) (0-8 scale), (2) decreased steatosis and (3) decreased hepatic lipid content (Oil Red O, P < 0.05 vs vehicle). Randomization of TAA animals and HFD fed animals to Senicapoc was associated with a decrease in liver fibrosis as evidenced by hydroxyproline and Masson's trichrome staining (P < 0.05 vs vehicle). These results demonstrated that Senicapoc mitigates both steatosis and fibrosis in liver fibrosis models. CONCLUSION: These data suggest that Senicapoc interrupts more than one node in progressive fatty liver disease by its anti-steatotic and anti-fibrotic activities, serving as a double-edged therapeutic sword.


Assuntos
Acetamidas/farmacologia , Regulação Neoplásica da Expressão Gênica , Canais de Potássio Ativados por Cálcio de Condutância Intermediária/antagonistas & inibidores , Hepatopatia Gordurosa não Alcoólica/tratamento farmacológico , Compostos de Tritil/farmacologia , Animais , Apoptose , Biomarcadores Tumorais/metabolismo , Dieta Hiperlipídica , Fibrose , Células Hep G2 , Humanos , Inflamação , Canais de Potássio Ativados por Cálcio de Condutância Intermediária/metabolismo , Cirrose Hepática/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Ácido Palmítico , Ratos , Ratos Wistar , Tioacetamida , Regulação para Cima
15.
PLoS One ; 11(10): e0163063, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27695033

RESUMO

Autosomal recessive polycystic kidney disease (ARPKD) is associated with progressive enlargement of the kidneys fuelled by the formation and expansion of fluid-filled cysts. The disease is congenital and children that do not succumb to it during the neonatal period will, by age 10 years, more often than not, require nephrectomy+renal replacement therapy for management of both pain and renal insufficiency. Since increasing cystic index (CI; percent of kidney occupied by cysts) drives both renal expansion and organ dysfunction, management of these patients, including decisions such as elective nephrectomy and prioritization on the transplant waitlist, could clearly benefit from serial determination of CI. So also, clinical trials in ARPKD evaluating the efficacy of novel drug candidates could benefit from serial determination of CI. Although ultrasound is currently the imaging modality of choice for diagnosis of ARPKD, its utilization for assessing disease progression is highly limited. Magnetic resonance imaging or computed tomography, although more reliable for determination of CI, are expensive, time-consuming and somewhat impractical in the pediatric population. Using a well-established mammalian model of ARPKD, we undertook a big data-like analysis of minimally- or non-invasive blood and urine biomarkers of renal injury/dysfunction to derive a family of equations for estimating CI. We then applied a signal averaging protocol to distill these equations to a single empirical formula for calculation of CI. Such a formula will eventually find use in identifying and monitoring patients at high risk for progressing to end-stage renal disease and aid in the conduct of clinical trials.


Assuntos
Biomarcadores , Rim Policístico Autossômico Recessivo/sangue , Rim Policístico Autossômico Recessivo/urina , Insuficiência Renal/sangue , Insuficiência Renal/urina , Animais , Biomarcadores/sangue , Biomarcadores/urina , Nitrogênio da Ureia Sanguínea , Criança , Creatinina/sangue , Cistatina C/sangue , Cistos/patologia , Receptor Celular 1 do Vírus da Hepatite A/sangue , Humanos , Interleucina-18/sangue , Rim/diagnóstico por imagem , Rim/metabolismo , Rim/fisiopatologia , Transplante de Rim , Lipocalina-2/sangue , Imageamento por Ressonância Magnética , Camundongos , Rim Policístico Autossômico Recessivo/diagnóstico por imagem , Rim Policístico Autossômico Recessivo/patologia , Ratos , Insuficiência Renal/patologia , Índice de Gravidade de Doença , Ultrassonografia
17.
Am J Physiol Heart Circ Physiol ; 282(4): H1311-9, 2002 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-11893566

RESUMO

We examined the contributions of the Ca(2+) channels of the sarcolemma and of the sarcoplasmic reticulum to electromechanical restitution. Extrasystoles (F(1)) were interpolated 40-600 ms following a steady-state beat (F(0)) in perfused rat ventricles paced at 2 or 3 Hz. Plots of F(1)/F(0) versus the extrasystolic interval consisted of phase I, which occurred before relaxation of the steady-state beat, and phase II, which occurred later. Phase I exhibited a period of enhanced left ventricular pressure development that coincided with action potential prolongation. Phase I was eliminated by -BAY K 8644 (100 nM) and FPL 64176 (150 nM), augmented by 3 microM thapsigargin plus 200 nM ryanodine and unaffected by KN-93 and KB-R7943. Phase II was accelerated by the Ca(2+) channel agonists and by isoproterenol but was eliminated by thapsigargin plus ryanodine. The results suggest that phase I of electromechanical restitution is caused by a transient L-type Ca(2+) current facilitation, whereas phase II represents the recovery of the ability of the sarcoplasmic reticulum to release Ca(2+).


Assuntos
Canais de Cálcio/fisiologia , Coração/fisiologia , Retículo Sarcoplasmático/fisiologia , Função Ventricular Esquerda/fisiologia , Éster Metílico do Ácido 3-Piridinacarboxílico, 1,4-Di-Hidro-2,6-Dimetil-5-Nitro-4-(2-(Trifluormetil)fenil)/farmacologia , Potenciais de Ação/fisiologia , Animais , Benzilaminas/farmacologia , Agonistas dos Canais de Cálcio/farmacologia , Bloqueadores dos Canais de Cálcio/farmacologia , Canais de Cálcio/efeitos dos fármacos , Inibidores Enzimáticos/farmacologia , Coração/efeitos dos fármacos , Frequência Cardíaca , Técnicas In Vitro , Isoproterenol/farmacologia , Masculino , Perfusão , Pirróis/farmacologia , Ratos , Ratos Sprague-Dawley , Rianodina/farmacologia , Sarcolema/fisiologia , Sulfonamidas/farmacologia , Sístole , Tapsigargina/farmacologia , Fatores de Tempo , Vasodilatação
18.
Am J Physiol Heart Circ Physiol ; 282(3): H1035-40, 2002 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-11834501

RESUMO

Adenosine A2a receptors are found in coronary vascular tissue although, their presence in myocardium is subject to investigation. Although there have been numerous studies on adenosine A2a receptor agonist effects on contractility and cAMP levels in ventricular myocytes, these have yielded conflicting results. Negative pharmacological studies have even led to the conclusion that A2a receptors are not present in cardiac myocytes. The purpose of this study was to determine whether A2a receptors are expressed in rat ventricular myocytes and what physiological effects are mediated via activation of these receptors. Western blot analysis with a polyclonal antibody raised against a peptide sequence specific to the carboxy terminus of the A2a receptor revealed the presence of a band at approximately 45 kDa. However, the immunoreactivity was located in the nonmembrane fraction of the cell lysate. The membrane fraction only exhibited an immunoreactive band > or = 50 kDa. Treatment of isolated myocytes with the adenosine A2a agonist 2-[4-[(2-carboxyethyl)-phenyl]ethylamino]-5'-N-ethylcarboxamidoadenosine (CGS-21680) exerted no effects on cAMP levels or myocyte twitch amplitude. These results indicate that although rat ventricular myocytes appear to express adenosine A2a receptors, stimulation with an A2a agonist exerts no functional effects, possibly because of the subcellular localization of the A2a receptor.


Assuntos
Adenosina/análogos & derivados , AMP Cíclico/metabolismo , Coração/fisiologia , Contração Miocárdica/fisiologia , Receptores Purinérgicos P1/fisiologia , Adenosina/farmacologia , Animais , Ventrículos do Coração , Humanos , Isoproterenol/farmacologia , Masculino , Miocárdio/citologia , Fenetilaminas/farmacologia , Inibidores de Fosfodiesterase/farmacologia , Agonistas Purinérgicos , Agonistas do Receptor Purinérgico P1 , Ratos , Ratos Sprague-Dawley , Receptor A2A de Adenosina , Receptores Purinérgicos P1/efeitos dos fármacos , Rolipram/farmacologia
19.
Am J Physiol Heart Circ Physiol ; 282(4): H1320-6, 2002 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-11893567

RESUMO

We examined mechanical alternans and electromechanical restitution in normal and failing rat hearts. Alternans occurred at 5 Hz in failing versus 9 Hz in control hearts and was reversed by 300 nM isoproterenol, 6 mM extracellular Ca(2+), 300 nM -BAY K 8644, or 50 nM ryanodine. Restitution curves comprised phase I, which was completed before relaxation of the steady-state beat, and phase II, which occurred later. Phase I action potential area and developed pressure ratios were significantly reduced in the failing versus control hearts. Phase II was a monoexponential increase in relative developed pressure as the extrasystolic interval was increased. The plateau of phase II was significantly elevated in failing hearts. Thapsigargin (3 microM) plus ryanodine (200 nM) potentiated phase I to a significantly greater extent in control versus failing hearts and abolished phase II in both groups. The results suggest that both regulation of Ca(2+) influx across the sarcolemma and Ca(2+) release by the sarcoplasmic reticulum may contribute to altered excitation-contraction coupling in the failing spontaneously hypertensive heart failure prone rat heart.


Assuntos
Cálcio/farmacologia , Insuficiência Cardíaca/fisiopatologia , Isoproterenol/farmacologia , Disfunção Ventricular Esquerda/fisiopatologia , Função Ventricular Esquerda/fisiologia , Potenciais de Ação , Animais , Frequência Cardíaca , Hipertensão/genética , Hipertensão/fisiopatologia , Masculino , Ratos , Ratos Endogâmicos BN , Ratos Endogâmicos , Ratos Endogâmicos WF , Ratos Wistar , Rianodina/farmacologia , Tapsigargina/farmacologia , Função Ventricular Esquerda/efeitos dos fármacos
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