Impact of calcium aluminate cement with additives on dental pulp-derived cells

Abstract Calcium aluminate cement (CAC) has been highlighted as a promising alternative for endodontic use aiming at periapical tissue repair. However, its effects on dental pulp cells have been poorly explored. Objective: This study assessed the impact of calcium chloride (CaCl2) and bismuth oxide (Bi2O3) or zinc oxide (ZnO) additives on odontoblast cell response to CAC. Methodology: MDPC-23 cells were exposed for up to 14 d: 1) CAC with 2.8% CaCl2 and 25% ZnO (CACz); 2) CAC with 2.8% CaCl2 and 25% Bi2O3 (CACb); 3) CAC with 10% CaCl2 and 25% Bi2O3 (CACb+); or 4) mineral trioxide aggregate (MTA), placed on inserts. Non-exposed cultures served as control. Cell morphology, cell viability, gene expression of alkaline phosphatase (ALP), bone sialoprotein (BSP), and dentin matrix protein 1 (DMP-1), ALP activity, and extracellular matrix mineralization were evaluated. Data were compared using ANOVA (α=5%). Results: Lower cell density was detected only for MTA and CACb+ compared with Control, with areas showing reduced cell spreading. Cell viability was similar among groups at days one and three (p>0.05). CACb+ and MTA showed the lowest cell viability values at day seven (p>0.05). CACb and CACb+ promoted higher ALP and BSP expression compared with CACz (p<0.05); despite that, all cements supported ALP activity. Matrix mineralization were enhanced in CACb+ and MTA. Conclusion: In conclusion, CAC with Bi2O3, but not with ZnO, supported the expression of odontoblastic phenotype, but only the composition with 10% CaCl2 promoted mineralized matrix formation, rendering it suitable for dentin-pulp complex repair.

Effect of a calcium hydroxide-based intracanal medicament containing N-2-methyl pyrrolidone as a vehicle against Enterococcus faecalis biofilm

Abstract This study investigated the effect of a calcium hydroxide (CH) paste (CleaniCal®) containing N-2-methyl pyrrolidone (NMP) as a vehicle on Enterococcus faecalis (E. faecalis) biofilms compared with other products containing saline (Calasept Plus™) or propylene glycol (PG) (Calcipex II®). Methodology Standardized bovine root canal specimens were used. The antibacterial effects were measured by colony-forming unit counting. The thickness of bacterial microcolonies and exopolysaccharides was assessed using confocal laser scanning microscopy. Morphological features of the biofilms were observed using field-emission scanning electron microscopy (FE-SEM). Bovine tooth blocks covered with nail polish were immersed into the vehicles and dispelling was observed. The data were analyzed using one-way analysis of variance and Tukey tests (p<0.05). Results CleaniCal® showed the highest antibacterial activity, followed by Calcipex II® (p<0.05). Moreover, NMP showed a higher antibacterial effect compared with PG (p<0.05). The thickness of bacteria and EPS in the CleaniCal® group was significantly lower than that of other materials tested (p<0.05). FE-SEM images showed the specimens treated with Calasept Plus™ were covered with biofilms, whereas the specimens treated with other medicaments were not. Notably, the specimen treated with CleaniCal® was cleaner than the one treated with Calcipex II®. Furthermore, the nail polish on the bovine tooth block immersed in NMP was completely dispelled. Conclusions CleaniCal® performed better than Calasept Plus™ and Calcipex II® in the removal efficacy of E. faecalis biofilms. The results suggest the effect might be due to the potent dissolving effect of NMP on organic substances.

Extracellular calcium increases fibroblast growth factor 2 gene expression via extracellular signal-regulated kinase 1/2 and protein kinase A signaling in mouse dental papilla cells

Abstract We previously reported that elevated extracellular calcium (Ca2+) levels increase bone morphogenetic protein 2 expression in human dental pulp (hDP) cells. However, it is unknown whether extracellular Ca2+ affects the expression of other growth factors such as fibroblast growth factor 2 (FGF2). Objective: The present study aimed to examine the effect of extracellular Ca2+ on FGF2 gene expression in hDP and immortalized mouse dental papilla (mDP) cells. Materials and Methods: Cells were stimulated with 10 mM CaCl2 in the presence or absence of cell signaling inhibitors. FGF2 gene expression was assessed using real-time polymerase chain reaction. The phosphorylation status of signaling molecules was examined by Western blotting. Results: Extracellular Ca2+ increased FGF2 gene expression in mDP and hDP cells. Gene expression of the calcium-sensing receptor and G protein-coupled receptor family C group 6 member A, both of which are extracellular Ca2+ sensors, was not detected. Ca2+-mediated Fgf2 expression was reduced by pretreatment with the protein kinase A (PKA) inhibitor H-89 or extracellular signal-regulated kinase (ERK) 1/2 inhibitor PD98059 but not by pretreatment with the protein kinase C inhibitor GF-109203X or p38 inhibitor SB203580. Extracellular Ca2+ increased PKA activity and ERK1/2 phosphorylation. Ca2+-induced PKA activity decreased by pretreatment with PD98059. Conclusions: These findings indicate that elevated extracellular Ca2+ levels led to increased Fgf2 expression through ERK1/2 and PKA in mDP cells and that this mechanism may be useful for designing regenerative therapies for dentin.

Physical properties and biological effects of mineral trioxide aggregate mixed with methylcellulose and calcium chloride

Abstract Objectives: Methylcellulose (MC) is a chemical compound derived from cellulose. MTA mixed with MC reduces setting time and increases plasticity. This study assessed the influence of MC as an anti-washout ingredient and CaCl2 as a setting time accelerator on the physical and biological properties of MTA. Material and Methods: Test materials were divided into 3 groups; Group 1(control): distilled water; Group 2: 1% MC/CaCl2; Group 3: 2% MC/CaCl2. Compressive strength, pH, flowability and cell viability were tested. The gene expression of bone sialoprotein (BSP) was detected by RT-PCR and real­ time PCR. The expression of alkaline phosphatase (ALP) and mineralization behavior were evaluated using an ALP staining and an alizarin red staining. Results: Compressive strength, pH, and cell viability of MTA mixed with MC/CaCl2 were not significantly different compared to the control group. The flowability of MTA with MC/CaCI2 has decreased significantly when compared to the control (p<.05). The mRNA level of BSP has increased significantly in MTA with MC/CaCl2 compared to the control (p<.05). This study revealed higher expression of ALP and mineralization in cells exposed to MTA mixed with water and MTA mixed with MC/CaCl2 compared to the control (p<.05). Conclusions: MC decreased the flowability of MTA and did not interrupt the physical and biological effect of MTA. It suggests that these cements may be useful as a root-end filling material.

Chemical sterilization of dogs using single bilateral intra-testicular injection of calcium chloride or clove oil

The current study was designed to evaluate the efficacy of single bilateral intra-testicular injection of calcium chloride or clove oil to induce chemical sterilization in ten dogs divided into two groups each of five animals. Chemical sterilization was evaluated by clinical signs, hormonal analysis and histopathological examination. Testosterone level was decreased significantly after injection of both agents with complete degeneration of the interstitial leydig cells and seminiferous tubules while cortisol level was increased during the 1[st] week after calcium chloride injection. The single bilateral intra-testicular injection of calcium chloride or clove oil proved to be accepted as a suitable alternative to the surgical sterilization of dogs; however clove oil was superior to calcium chloride as it induced less pain and irritation to the dogs

Antihypertensive and vasorelaxant effects of ethanol extract of stem barks from Zanthoxylum rhoifolium Lam in rats.

Administration of ethanol extract of stem bark from Z. rhoifolium (EEtOH-ZR) induced hypotension associated with a dual effect in heart rate in normotensive rats. This response was highlighted in spontaneously hypertensive rats (SHR). In rat superior mesenteric artery rings, the cumulative addition of EEtOH-ZR (0.1–750 µg/mL) on a phenylephrine-induced pre-contraction (10-5 M) promoted a vasorelaxant effect by a concentration-dependent manner and independent of vascular endothelium. A similar effect was obtained on KCl-induced pre-contractions (80 mM). EEtOH-ZR attenuated contractions induced by cumulative addition of CaCl2 (10-6–3 × 10-2 M) in depolarizing medium without Ca2+ only at 500 or 750 µg/mL. Likewise, on S-(–)-Bay K 8644-induced pre-contractions (10-7 M), the EEtOH-ZR-induced vasorelaxant effect was attenuated. EEtOH-ZR (27, 81, 243 or 500 µg/mL) inhibited contractions induced by cumulative addition of phenylephrine (10-9 - 10-5 M) in endothelium-denuded preparations or by a single concentration (10-5 M) in a Ca2+-free medium. The involvement of K+ channels was evaluated by tetraethylammonium (3 mM); the EEtOH-ZR-induced vasorelaxation was not attenuated. Thus, calcium influx blockade through voltage-operated calcium channels (CaVL) and inhibition of calcium release from intracellular stores are probably underlying EEtOH-ZR-induced cardiovascular effects.

Comparative experimental study of myocardial protection with crystalloid solutions for heart transplantation / Estudo comparativo experimental da proteção miocárdica com soluções cristalóides para transplante cardíaco

BACKGROUND: There is a growing need to improve myocardial protection, which will lead to better performance of cardiac operations and reduce morbidity and mortality. Therefore, the objective of this study was to compare the efficacy of myocardial protection solution using both intracellular and extracellular crystalloid type regarding the performance of the electrical conduction system, left ventricular contractility and edema, after being subjected to ischemic arrest and reperfusion. METHODS: Hearts isolated from male Wistar (n=32) rats were prepared using Langendorff method and randomly divided equally into four groups according the cardioprotective solutions used Krebs-Henseleit-Buffer (KHB), Bretschneider-HTK (HTK), St. Thomas-1 (STH-1) and Celsior (CEL). After stabilization with KHB at 37ºC, baseline values (control) were collected for heart rate (HR), left ventricle systolic pressure (LVSP), maximum first derivate of rise left ventricular pressure (+dP/dt), maximum first derivate of fall left ventricular pressure (-dP/dt) and coronary flow (CF). The hearts were then perfused at 10ºC for 5 min and kept for 2 h in static ischemia at 20ºC in each cardioprotective solution. Data evaluation was done using analysis of variance in completely randomized One-Way ANOVA and Tukey's test for multiple comparisons. The level of statistical significance chosen was P<0.05. RESULTS: HR was restored with all the solutions used. The evaluation of left ventricular contractility (LVSP, +dP/ dt and -dP/dt) showed that treatment with CEL solution was better compared to other solutions. When analyzing the CF, the HTK solution showed better protection against edema. CONCLUSION: Despite the cardioprotective crystalloid solutions studied are not fully able to suppress the deleterious effects of ischemia and reperfusion in the rat heart, the CEL solution had significantly higher results followed by HTK>KHB>STH-1.

INTRODUÇÃO: Existe crescente necessidade de aprimorar a proteção miocárdica, para melhor desempenho das operações cardíacas e diminuição da morbimortalidade. Portanto, o objetivo deste estudo foi comparar a eficácia da proteção miocárdica usando tanto solução cristaloide tipo intracelular como extracelular quanto ao desempenho do sistema de condução elétrica, contratilidade do ventrículo esquerdo e edema, após parada isquêmica e posterior reperfusão. MÉTODOS: Corações isolados de ratos Wistar foram montados em Langendorff e aleatoriamente divididos em quatro grupos. de acordo com as soluções cardioprotetoras utilizadas Krebs-Henseleit-Buffer (KHB), Bretschneider-HTK (HTK), St. Thomas-1(STH-1) e Celsior (CEL). Após a estabilização com KHB a 37ºC, valores basais (controle) foram coletados para frequência cardíaca (FC), pressão sistólica do ventrículo esquerdo (PSVE), derivada máxima de aumento da pressão ventricular esquerda (+dP/dt), derivada máxima de queda da pressão ventricular esquerda (-dP/dt) e fluxo coronariano (FCo). Os corações foram então perfundidos a 10ºC por 5 min e mantidos por 2 h em isquemia estática a 20ºC em cada solução cardioprotetora. Avaliação dos dados foi por análise de variância inteiramente casualizados em One-Way ANOVA e teste de Tukey para comparações múltiplas. O nível de significância estatística escolhido foi P<0,05. RESULTADOS: Houve recuperação da FC com todas as soluções utilizadas. A avaliação da contratilidade ventricular esquerda (PSVE, +dP/dt e -dP/dt) demonstrou que o tratamento com a solução CEL foi melhor em comparação às outras soluções. Ao analisar o CF, a solução HTK indicou melhor proteção contra edema. CONCLUSÃO: Apesar das soluções cristaloides cardioprotetoras estudadas não serem capazes de suprimir os efeitos deletérios da isquemia e reperfusão no coração de ratos, a solução CEL apresentou resultado superior seguido por HTK>KHB>STH-1.

Elevated ferric, calcium and magnesium ions in the brain induce protein aggregation in brain mitochondria / El aumento de iones férricos, calcio y magnesio en el cerebro induce la agregación de proteínas en las mitocondrias del cerebro

OBJECTIVE: Alzheimer s disease and Parkinson s disease are two of several neurodegenerative disorders that affect the elderly. Although their aetiology remains uncertain, studies suggest that elevated aluminium or other metal ions in the brain directly influence the development of the histological abnormalities normally associated with these diseases; other investigations suggest that metal-ion-induced-dysfunction of mitochondria might be a critical factor. METHODS: In this study, the impact of elevated aluminum (Al3+), ferric (Fe3+), calcium (Ca2+) and magnesium (Mg2+) ions on brain histology and on the protein composition of brain mitochondria were evaluated. Rabbits were injected intra-cerebrally with 1.4% solutions of either aluminium chloride (AlCl3), ferric chloride (FeCl2), calcium chloride (CaCl2) or magnesium chloride (MgCl2) and sacrificed 10 days later. RESULTS: Histological analysis revealed that Al3+ but not the other ions induced neurofibrillary degeneration within the midbrain and medulla. Alternatively, SDS-PAGE revealed that Fe3+, Ca2+ and Mg2+ but not Al3+ induced alterations to the distribution of brain mitochondrial proteins. Both Fe3+ and Ca2+ triggered decreased concentration of three low molecular weight proteins (~7-14 kd) but Ca precipitated their total absence. Both ions led to increased concentration of a high molecular weight protein (~ 110 kd). In contrast, Mg2+ led to the total absence of the protein of lowest molecular weight (~7 kd) and increased concentration of a ~36 kd protein. CONCLUSION: These results suggest that elevation of some metal ions in the brain induces protein aggregation with the nature of the aggregation being highly ion dependent. The results also point toward major differences between the histopathological effect of Al3+ and other ions.

OBJETIVO: La enfermedad de Alzheimer y la enfermedad de Parkinson son dos de los varios trastornos neurodegenerativos que afectan al anciano. Aunque su etiologia sigue siendo incierta, los estudios sugieren que el aumento de los iones de aluminio, influyen directamente sobre el desarrollo de las anormalidades histológicas asociadas normalmente con estas enfermedades. Otras investigaciones sugieren que la disfunción de las mitocondrias, inducida por iones metálicos, pudiera ser un factor critico. MÉTODOS: Este estudio evalúa el impacto del aumento de los iones de aluminio (Al3+), los iones férricos (Fe3+), y los iones de calcio (Ca2+) y magnesio (Mg2+) sobre la histologia del cerebro y la composición proteica de las mitocondrias del cerebro. Un número de conejos recibieron inyecciones intracerebrales de soluciones al 1.4% de soluciones de cloruro de aluminio (AlCl3), cloruro ferroso (FeCl3), cloruro de calcio (CaCl2), o cloruro de magnesio (MgCl2), y fueron sacrificados después de 10 días. RESULTADOS: El análisis histológico reveló que el Al3+ indujo una degeneración neurofibrilar dentro del mesencéfalo y la médula, Sin embargo, esto no ocurrió con los otros iones. Alternativamente, la técnica de electroforesis SDS-PAGE reveló que los iones Fe3+, Ca2+ y Mg2+, a diferencia del ión Al3+, inducían alteraciones de la distribución de las proteínas mitocondriales cerebrales. Tanto el Fe3+ como el Ca2+ desencadenaron una disminución de la concentración de tres proteínas de bajo peso molecular (~7-14 kd) pero Ca2+ precipitó su ausencia total. Ambos iones condujeron a un aumento de una proteína de peso molecular alto (~ 110 kd). En cambio, Mg2+ llevó a la ausencia total de la proteína de más bajo peso molecular (~7 kd) y al aumento de la concentración de una proteína de ~36 kd. CONCLUSIÓN: Estos resultados parecen sugerir que la elevación de algunos iones de metal en el cerebro induce la agregación de la proteína, siendo la naturaleza de la agregación altamente dependiente de los iones. Los resultados también apuntan a grandes diferencias entre el efecto histopatológico del Al3+ y otros iones.

Trimetazidina como aditivo em solução cardioplégica sem pré-tratamento não traz proteção adicional ao miocárdio isquêmico: estudo em modelo suíno de coração isolado / Trimetazidine as cardioplegia addictive without pre-treatment does not improve myocardial protection: study in a swine working heart model

OBJETIVO: Verificar, em modelo experimental de coração isolado de suínos, se a associação da trimetazidina à solução cardioplégica promove melhora no desempenho do coração. MÉTODOS: O modelo experimental utilizou suínos Large-White, com coração isolado perfundido por suporte de outro animal em modo de execução de trabalho ("working heart state"). Foram divididos em três grupos (n = 6), submetidos a isquemia regional seguida de isquemia global, que recebiam um dos três tratamentos: solução St Thomas (ST), solução St Thomas acrescida de trimetazidina (TMZ) e grupo controle (Co). Durante período de reperfusão, aos 30, 60 e 90 minutos, foram medidos parâmetros hemodinâmicos de contratilidade e metabólicos, obtendo-se assim a elastância máxima (Emáx), o índice de trabalho sistólico pré-recrutável (PRSW), "dureza" do ventrículo (EDPRV), fluxo coronariano, consumo de oxigênio e dosagens de lactato e glicose. Os resultados foram analisados estatisticamente. RESULTADOS: Em relação aos parâmetros hemodinâmicos de contratilidade, não houve diferença estatística significante entre os três grupos. Houve produção crescente de lactato nos três grupos de forma uniforme quanto maior o tempo de reperfusão. O fluxo coronariano, o consumo de oxigênio e o consumo de glicose tiveram grande variação entre os diferentes tempos medidos, mas sem diferença entre os três tratamentos. O peso final do ventrículo esquerdo foi significativamente menor no grupo trimetazidina (TMZ) do que nos demais. CONCLUSÃO: A administração da trimetazidina associada como adjuvante à solução cardioplégica, sem pré-tratamento, não demonstrou benefício hemodinâmico ou metabólico em modelo experimental "working heart" de coração isolado em porcos.

OBJECTIVE: The aim of this study is to verify in an isolated working heart swine model if the acute administration of trimetazidine to cardioplegia, without pre=treatment improves heart performance. METHODS: Eighteen pairs of swines were used in this working heart model, divided into three groups (n = 6) that underwent regional and global ischemia. Each group was selected to a different treatment: St Thomas cardioplegia (ST), St Thomas enriched with trimetazidine (TMZ) and control group (Co). Data was collected during reperfusion period at 30, 60 and 90 minutes. Hemodinamic parameters such as elastance contractility index (Emax), preload recruitable stroke work relationship (PRSW) and heart "stiffness" (EDPVR) were measured. Other data included coronary flow, lactate, oxygen and glucose consumption. Results were statistically analyzed. RESULTS: All contractility data were not significantly different among three groups. Lactate became constantly higher according to time uniformly in all three groups. Coronary flow, glucose consumption and oxygen consumption presented large variations during time periods but according to treatments showed no statistical differences in all three groups. Left ventricle final weight was significantly lower in trimetazidine group compared to both other groups. CONCLUSION: Administration of trimetazidine enhanced cardioplegia, without pre-treatment, showed no hemodinamic or metabolic improvement in swine isolated working heart model.

Preparation of Collagen Modified Hyaluronan Microparticles as Antibiotics Carrier

Hyaluronan (HA), a natural glycoaminoglycan featuring an extracellular matrix, has been suggested as an effective biocompatible material. In this study, the effectiveness of HA microparticles as a carrier system for antibiotics was evaluated, and their physicochemical characteristics were determined. Microparticles were fabricated by the gelation of sulfadiazine (SD) loaded HA solution with calcium chloride through either a granulation (GR-microparticles) or encapsulation (EN-microparticles) process, and atelocollagen was incorporated into the microparticles as an additive in order to improve their physical properties. The characteristics of the microparticles were examined by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and swelling test. In vitro release experiments were performed for 7 days and the released amount of SD was determined using high-performance liquid chromatography (HPLC). Microscopic observations revealed that the collagen incorporated HA particles had a more compact surface than the HA particles. DSC analysis determined a loss of SD crystallinity in the particles. Calcium chloride retarded the swelling of particles, whereas the loaded drug contents did not affect this property. Both GR-and EN-microparticles sustained SD release with initial bursting effect. SD release from EN-microparticles was faster than from GR- microparticles. In addition, the release rate was dependent on the SD content in the microparticles. These results suggest that collagen modified HA microparticles have a potential as a release rate controlling material for crystalline drugs such as SD.

In vitro effects of three metallic salts and soot on the growth of five species of the dermatophytes.

The antifungal effects of zinc chloride (znCl), Calcium chloride (CaCl), magnesium chloride (MgCl) as well as soot collected from a local kitchens were tested on five isolated species of the dermatophytes from cases of human dermatophytoses. Of these three metallic salts, ZnCl showed the highest inhibitory effect on the dermatophytes. At a concentration of 0.01 M it showed 100% inhibition on these fungi. Although the other two metallic salts showed some inhibitory effect CaCl at concentration between 0.01 M and 1 M showed only 50% inhibitory effect while MgCl at concentration between 0.1 M and 1 M showed less than 50% inhibitory effect on the fungi. Also soot inhibited the growth of all the dermatophytes tested at concentration between 0.1 and 2%. Trichophyton rubrum and Microspum audouinii appeared to be most sensitive to these compounds compared to the other three species which include T. mentagrophytes, T. tonsurans and M. gypseum.

Factors affecting transformation efficiency of BCG with a Mycobacterium-Escherichia coli shuttle vector pYUB18 by electroporation

BCG has been one of the vehicles for multi-recombinant vaccine. However, low transformation efficiency of BCG with plasmid DNA hampered studies involving expression of foreign antigens in BCG. In an effort to determine the optimal conditions, this study was initiated to investigate factors involved in the transformation of BCG with a Mycobacterium-Escherichia coli shuttle vector, pYUB18, by electroporation. Mycobacterium bovis BCG (strain 1173P2) was grown in Middlebrook (M) 7H9 broth containing albumin-dextrose-catalase and 0.05% tween 80, and transformed BCG was grown in M7H10 agar containing kanamycin for counting viable cells. Pretreatment of BCG with 10 mM CaCl2 improved the transformation efficiency, but overnight incubation of BCG with 1% glycine did not. The transformation efficiency in BCG also varied depending on voltage, resistance, and DNA concentration. The maximum transformation efficiency was obtained when the infinity resistance, 12.5 Kv/cm, and 100 ng of DNA were used, and reached 1.4 x 10(5) CFU/microgram of plasmid DNA, which is about 3-100 times greater than those from previous reports. The transformation conditions described in this study, therefore, will give us a better position for employing BCG as a vehicle for developing multi-recombinant vaccines.

role of magnesium and calcium ions in atrial natriuretic peptide secretion

For the purpose of examining the role of calcium and magnesium ions in the secretory process of atrial natriuretic peptide [ANP], we studied the effects of hypercalcemia, digitalis "Lanoxine", calcium ion channel blocker "verapamil", hypermagnesemia, potassium ion channel blocker "Glibenclamid", and potassium ion channel opener "cromakalim" on plasma concentration of immunoreactive ANP [ir ANP]. Pentobarbital-anesthetized dogs [n-36] were divided into-6-equal groups [6 each] and treated separately with calcium chloride infusion [0.136 mmol/Kg/min-10 min]. Lanoxine injection [30 micro g/Kg], verapamil injection [300 micro g/Kg], magnesium sulfate infusion [0.168 mmol/Kg/min-10 min] after an initial bolus dose of 1.5 mmol/Kg, glibenclamid injection [0.3 mg/Kg], and cromakalim injection [10 micro g/Kg]. Plasma ir ANP concentrations, mean arterial pressure [MAP], heart rate [HR] and serum calcium and magnesium concentrations were measured. With calcium chloride and magnesium sulfate infusions, serum calcium and magnesium levels and plasma ir ANP concentrations were significantly increased. Also, lanoxine and K[+] -channel blocker "glibenclamid" caused a significant increase in plasma ir ANP concentration while verapamil and the K[+]-channel opener "cromakalim" resulted in a significant decrease. Neither calcium chloride nor lanoxine produced a significant effect on heart rate, but both significantly increased MAP. In contrast, magnesium sulfate and verapamil produced a significant decrease in MAP and HR while glibenclamid and cromakalim were associated with insignificant changes in both HR and MAP. These results suggest that calcium ions may play a key role in the secretory process of ANP and indicate that magnesium ions may also influence ANP secretion by acting via modulation of K[+] -channels

Kinetic studies on the membrane form of intestinal alkaline phosphatase

We have purified different membrane and soluble forms of alkaline phosphatase from human placenta and bovine intestine. The enzymes will be used as markers in immunoconjugates and/or as model for membrane enzyme studies. The membrane formof alkaline phosphatase extracted from bovine intestine was purified on Q-Sepharose and on L-histidyldiazobenzylphosphonic acid-agarose columns to remove phosphodiesterase activity. The purified enzyme had a molecular mass of 61 kDa, Km of 1208 µM, and Vmax 240 µmol pNP/min when assayed in 1 M diethanolamine, 0.5 mM MgCl2 buffer, pH 9.8, containing 10 to 2250 µM of pNPP at 37§C. In the present investigation we studied the effect of salts and inositol derivatives on this enzyme activity, which was found to depend on 0.5 mM Mg2+, and to be fully inhibited by 1.2 mM Hg2+. Vanadate (0.5 mM) and Zn2+ (0.5 mM) reduced the Km value by 43 percent and 84 percent, respectively. Inositol (2 mM) and inositol-2-monophosphate (2 mM) reduced the activity by 23 percent and 17 percent. Inositol-1-monophosphate (0.5 mM) and cyclic-inositol-(1:2)-monophosphate (0.5 mM) enhanced their Km value by at least 30 percent compared to p-nitrophenylphosphate

Enhanced Na-K ATPase activity in the aorta may explain the unaltered contractile responses to KCl in diabetes mellitus.

Sodium-potassium ATPase activity and transmembrane calcium influx in the aortic smooth muscle from control and diabetic rats were assessed indirectly through the measurement of KCl relaxation and contractile responses to CaCl2 in attempts to explain the contractile responses to KCl following streptozotocin-induced diabetes mellitus. There were no significant changes in the maximum contractile responses of the aortas from 4 and 12 week diabetic rats to KCl even when significant increases in calcium influx were demonstratable. On the other hand, the diabetic aortas were significantly (P < 0.05) more sensitive to KCl-induced relaxations than the controls. This provides an indirect evidence for increased activity of the sodium-postassium ATPase enzyme in the aortas from streptozotocin diabetic rats. This may, atleast in part, explain the inability of KCl to produce greater than normal contractions of the aortas from diabetic rats.

A kinetic study of some factors which influence the intestinal absorption of calcium in rats

Rats weighing 100 ñ 8 g were used in an in vivo kinetic study of the intestinal absorption of calcium (CaA) from there systems: 1) CaCl2, 2) whole cow's milk (M), and 3) a taple Brazilian diet (SBD). Food substrates were treated with HCl, neutralized and diluted with 0.15 mM NaCl to different concentrations. Each dilution was assayed by introducing 2 ml into the small intestine and the final amount of Ca*+ in the small intestine was determined 30 min later. The values for velocity (v= Vmax (Ca*+ in the small intestine was determined 30 min later. The values for velocity (v+Vmax (Ca*+)/(Ca*+) + Km) and affinity (1/Km) for the food substrates were 1.35, 15.51 and 2.31 *g Ca*+/min and 0.29, 0,016 and 0.266 *g Ca*+/ml, respectively. We conclude that the higher affinities observed for CaCl2 and SBD were not correlated with velocity. Factors modifying CaA appear to be protein (stimulator) and phylate and fiber (inhibitors)

Efectos del calcio sobre la funcion diastolica del ventriculo izquierdo en perros anestesiados / Effects of calcium on left ventricular diastolic function in anesthetized dogs

En el presente trabajo se estudiaron los efectos del calcio sobre la función diastólica del ventrículo izquierdo en el perro anestesiado con tórax abierto. Se consideró la fase diastólica en su totalidad, esto es, relajación isovolúmica, llendo rápido, y propiedades pasivas del miocardio. Los animales fueron instrumentados con un transductor para medir presión del ventrículo izquierdo (PVI), y dos pares de cristales que permitieron medir diámetro interno (DI) y espesor y expesor de pared (EP), lo cual permitió calcular "stress" de fin de diástole (SFD), y de fin de sístole (SFS), como índices de pre y poscarga respectivamente. La función diastólica fue evaluada a través de la constante de tiempo de caída de la presión isovolúmica (Pi), calculada por el método de asíntota variable, el cociente entre las máximas velocidades de aumento y caída de PVI (+dP?dt?-dp?dt) max, el cociente entre ambas velocidades a una presión de 35 mmHg, la velocidad pico de estiramiento del ventrículo izquierdo (+dD/dtmax), y la constante de rigidez pasiva de cámara (Kc). La rigidez de cámara fue calculada utilizando el concepto de presión pasiva de llenado para evitar la participación del proceso de relajación en el llenado ventricular. Una dosis única de calcio fue administrada en cada perro por vía endovenosa. En un segundo grupo de animales esa única dosis fue dada despuês de la inducción de bloqueo ß-adrenérgico con propranolol. El calcio no cambió la precarga ni la postcarga. La +dP/dtmax aumentó porcentualmente más que la -dp/dtmax. El cociente a una presión de 35 mmHg (+dP/dt/-dp/dt)35 no se modificó. El Pi no cambió, pero disminuyó significativamente el valor de la síntota. La +dD/dtmax aumentó, mientras que constante de rigidez no mostró cambios significativos. El bloqueo ß-adrenérgico no alteró los resultados obtenidos con el cloruro de calcio en los animales con el sistema nervioso autónomo intacto. Se concluye que el calcio: a) no modificó la fase de relajación insovulúmica, pero negativizó el valor de la asíntota; b) aumentó la velocidad máxima de llenado; 3) no cambió la constante de rigidez miocárdica