[Health education trough the development of scientific skills in Chilean schools]. / Educación en salud a través del desarrollo de habilidades científicas en escolares chilenos.

OBJECTIVE:: To describe the interests, preferred topics and learning in public health issues emerging from Chilean students with their participation in a science education experience. MATERIALS AND METHODS:: A qualitative exploratory study was conducted in 29 school research groups through the project Salud Con-Ciencia en tu Barrio, based on a content analysis of texts and narratives of students. RESULTS:: Students prioritize the situation of abandoned animals, waste management, security and urban infrastructure, mainly. They view the role of social actors, the positive/negative impacts on the community, valuing the knowledge gained through observation neighborhoods and interaction with neighbors. CONCLUSIONS:: Scientific inquiry school in the neighborhood context provides teaching strategies for the promotion of local health, develops basic notions of community health and motivation in students linked to the socio-environmental reality of their neighborhoods.

Primary Apical Stability of Tapered Implants Through Reduction of Final Drilling Dimensions in Different Bone Density Models: A Biomechanical Study.

PURPOSE: A biomechanical study of the primary apical stability obtained in tapered implants through the reduction of final drilling dimensions in different bone density models. MATERIAL AND METHODS: An in vitro study of maximum insertion torque and primary stability based on the resonance frequency analysis (RFA) of 24 conical implants measuring 13 mm in length and 3.75 and 4.20 mm in diameter, randomly inserted in 10-mm sockets prepared in 4 polyurethane blocks with a density of 15, 20, 30, and 40 pounds per cu ft, respectively, reducing the diameter of the final drill at constant speed (400 rpm) to obtain exclusive 4 mm anchoring of the apical third of each implant. RESULTS: The decrease in drilling diameter resulted in an increase in the insertion torque and implant stability quotient (ISQ) values in all implants, although without reaching statistical significance. In turn, a significant direct correlation was found between increasing bone analog block density and the insertion torque and ISQ values. CONCLUSIONS: Under the conditions of this study, the primary apical stability obtained may be more dependent on bone density than on reduction of the final drilling diameter.

Human umbilical artery smooth muscle exhibits a 2-APB-sensitive capacitative contractile response evoked by vasoactive substances and expresses mRNAs for STIM, Orai and TRPC channels.

After depletion of intracellular Ca2+ stores the capacitative response triggers an extracellular Ca2+ influx through store-operated channels (SOCs) which refills these stores. Our objective was to explore if human umbilical artery smooth muscle presented this response and if it was involved in the mechanism of serotonin- and histamine-induced contractions. Intracellular Ca2+ depletion by a Ca(2+)-free extracellular solution followed by Ca2+ readdition produced a contraction in artery rings which was inhibited by the blocker of Orai and TRPC channels 2-aminoethoxydiphenyl borate (2-APB), suggesting a capacitative response. In presence of 2-APB the magnitude of a second paired contraction by serotonin or histamine was significantly less than a first one, likely because 2-APB inhibited store refilling by capacitative Ca2+ entry. 2-APB inhibition of sarcoplasmic reticulum Ca2+ release was excluded because this blocker did not affect serotonin force development in a Ca(2+)-free solution. The PCR technique showed the presence of mRNAs for STIM proteins (1 and 2), for Orai proteins (1, 2 and 3) and for TRPC channels (subtypes 1, 3, 4 and 6) in the smooth muscle of the human umbilical artery. Hence, this artery presents a capacitative contractile response triggered by stimulation with physiological vasoconstrictors and expresses mRNAs for proteins and channels previously identified as SOCs.

Early alterations in vascular contractility associated to changes in fatty acid composition and oxidative stress markers in perivascular adipose tissue.

AIM: To test the early effect of fructose-induced changes in fatty acid composition and oxidative stress markers in perivascular adipose tissue (PVAT) upon vascular contractility. METHODS: Adult male Wistar rats were fed a commercial diet without (CD) or with 10% fructose (FRD) in the drinking water for 3 weeks. We measured plasma metabolic parameters, lipid composition and oxidative stress markers in aortic PVAT. Vascular contractility was measured in aortic rings sequentially, stimulated with serotonin (5-HT) and high K+-induced depolarization using intact and thereafter PVAT-deprived rings. RESULTS: Comparable body weights were recorded in both groups. FRD rats had increased plasma triglyceride and fructosamine levels. Their PVAT had an increased saturated to mono- or poly-unsaturated fatty acid ratio, a significant decrease in total superoxide dismutase and glutathione peroxidase activities and in the total content of glutathione. Conversely, lipid peroxidation (TBARS), nitric oxide content, and gluthathione reductase activity were significantly higher, indicating an increase in oxidative stress. In aortic rings, removal of PVAT increased serotonin-induced contractions, but the effect was significantly lower in rings from FRD rats. This effect was no longer observed when the two contractions were performed in PVAT-deprived rings. PVAT did not affect the contractions triggered by high K+-induced depolarization either in CD or FRD rats. CONCLUSIONS: FRD induces multiple metabolic and endocrine systemic alterations which also alter PVAT and the vascular relaxant properties of this tissue. The changes in PVAT would affect its paracrine modulation of vascular function.

Thermal increment due to ErCr:YSGG and CO2 laser irradiation of different implant surfaces. A pilot study.

OBJECTIVE: An evaluation and comparison is made of the thermal increment at different implant surfaces during irradiation with CO2 and ErCr:YSGG lasers. STUDY DESIGN: Five threaded and impacted implants with four types of surfaces were inserted in an adult pig rib: two implants with a hydroxyapatite surface (HA) (impacted and threaded, respectively), a machined titanium surface implant (TI mach), a titanium plasma spray surface implant (TPS), and a sandblasted, acid-etched surface implant (SBAE). A 0.5-mm diameter bone defect was made in the implant apical zone, and a type-K thermocouple (Termopar) was placed in contact with the implant. The implants were irradiated in the coronal zone of each implant with a CO2 (4 W continuous mode) and an ErCr:YSGG laser (1.5 W, pulsed mode) first without and then with refrigeration. The temperature variations at the implant apical surface were recorded. RESULTS: An apical temperature increase was recorded in all cases during CO2 and ErCr:YSGG laser irradiation without refrigeration. However, when the ErCr:YSGG was used with a water spray, a decrease in temperature was observed in all implants. The acid-etched and sandblasted surfaces were those most affected by the thermal changes. CONCLUSIONS: The ErCr:YSGG laser with a water spray applied to the sealing cap or coronal zone of the implants does not generate thermal increments in the apical surface capable of adversely affecting osseointegration and the integrity of the peri-implant bone tissue.

Comparative study of the anesthetic efficacy of 4% articaine versus 2% lidocaine in inferior alveolar nerve block during surgical extraction of impacted lower third molars.

BACKGROUND: A comparative study is made of the anesthetic efficacy of 4% articaine versus 2% lidocaine, both with epinephrine 1:100,000, in truncal block of the inferior alveolar nerve during the surgical extraction of impacted lower third molars. STUDY DESIGN: A randomized double-blind clinical trial was conducted of 30 patients programmed for the bilateral surgical extraction of symmetrical lower third molars in the context of the Master of Oral Surgery and Implantology (University of Barcelona, Barcelona, Spain). Following the obtainment of informed consent, two operators performed surgery on an extemporaneous basis, using as local anesthetic 4% articaine or 2% lidocaine with the same concentration of vasoconstrictor (epinephrine 1:100,000). The study variables for each anesthetic were: latency (time to action) and duration of anesthetic effect, the amount of anesthetic solution used, and the need of re-anesthetize the surgical zone. A visual analog scale was used to assess pain during surgery, and thus subjectively evaluate the anesthetic efficacy of the two solutions. RESULTS: Statistically significant differences (p = 0.003) were observed in the mean duration of anesthetic effect (220.86 min. for 4% articaine vs. 168.20 min. for 2% lidocaine). Latency, the amount of anesthetic solution and the need to re-anesthetize the surgical field showed clinical differences in favor of articaine, though statistical significance was not reached. The pain scores indicated similar anesthetic efficacy with both solutions. CONCLUSIONS: The results obtained suggest that 4% articaine offers better clinical performance than 2% lidocaine, particularly in terms of latency and duration of the anesthetic effect. However, no statistically significant differences in anesthetic efficacy were recorded between the two solutions.

pH effects on high conductance Ca2+-activated K+ channels (BK(Ca)) in human internal mammary artery smooth muscle cells.

INTRODUCTION: In vascular smooth muscle cells, different types of K+ channels participate in the regulation of membrane potential and consequently in the contractile behavior of the vessel. There is little information about the properties and role of K+ channels in human internal mammary artery (HIMA), the vessel of choice for coronary revascularization. METHODS: Patch-clamp technique on isolated HIMA smooth muscle cells was used. RESULTS: This work presents for the first time single-channel properties of the high conductance Ca2+-activated K+ channel (BK(Ca)) of HIMA. It presents a single-channel conductance of 228+/-4 pS (n=44, 8 cells), is sensitive to 100 nM iberiotoxin, and its open probability is Ca2+- and voltage-dependent. Inside-out results show that BK(Ca) channels in HIMA are directly activated by increasing the pH of intracellular media (NPo=0.096+/-0.032 at pH 7.4 and NPo=0.459+/-0.111 at pH 7.6, n=12 cells, p<0.05) and inhibited by lowering this pH (NPo=0.175+/-0.067 at pH 7.4 and NPo=0.051+/-0.019 at pH 6.8, n=13 cells, p<0.05). CONCLUSIONS: The evidences presented about single-channel properties and intracellular pH sensitivity of BK(Ca) from HIMA smooth muscle cells provide useful information to elucidate physiological or pathological mechanisms in this vessel, as well as for future studies where drugs could have BK(Ca) channels as targets for pharmacological therapies.

Dimensiones de la cresta ósea vestibular en incisivos maxilares con indicación de implantes inmediatos. Un estudio transversal y sus implicaciones en el plan de tratamiento / Dimensions of facial bone ridge in maxillary incisors with immediate implants indication. A cross-sectional study and treatment plan implications

RESUMEN: Objetivo: Determinar las dimensiones de la cresta ósea vestibular de los incisivos maxilares con indicación de implantación inmediata. Pacientes y método: Un estudio transversal fue realizado en pacientes con necesidad de colocación de implantes inmediatos unitarios en la zona incisiva superior, durante el periodo de Enero-2015 a Diciembre-2017. Cortes tomográficos sagítales fueron utilizados para determinar la altura y el grosor de la cresta ósea alveolar vestibular. El punto de medición del grosor fue localizado a 4 mm apical a la linea amelocementaria. Un análisis T-student, fue utilizado para comparar las variables según la edad, el género y el grupo dentario, con un intervalo de confianza de 95%. Resultados: 298 imágenes fueron incluidas en la evaluación. El promedio de altura fue 10,68 mm, no hubo diferencias al comparar los grupos. El grosor promedio fue de 0,73 mm, diferencias de grosor, estadísticamente significativas, fueron observadas al comparar la edad y el género, no así en el grupo dentarlo. Conclusiones: La altura del hueso alveolar vestibular de incisivos superiores es suficiente para colocar implantes inmediatos dentro de un marco óseo. No obstante, el grosor observado, se traduciría en la necesidad de complementar la implantación con técnicas de regeneraciónn tisular guiada.

ABSTRACT: Objective : Determine the dimensions of the facial bone ridge of the maxillary incisors with indication of immediate implantation. Patients and method: A cross-sectional study was carried out in patients in need of single immediate implant placement in the upper incisor area, during the period from January-2015 to December-2017. Sagittal tomographic sections were used to determine the height and thickness of the vestibular alveolar bone ridge. The thickness measurement point was located 4 mm apical to the amelocementary junction. A T-student analysis was used to compare the variables according to age, gender, and dental group, with a 95% confidence interval. Results: 298 images were included in the evaluation. The mean height was 10.68 mm, there were no differences when comparing the groups. The mean thickness was 0.73 mm, statistically significant differences in thickness were observed when comparing age and gender, but not in the dental group. Conclusions: The height of the vestibular alveolar bone of the upper incisors could be sufficient to place immediate implants within a bone framework. However, the thickness observed would result in the need to complement the implantation with guided tissue regeneration techniques.

Potassium channels in human umbilical artery cells.

OBJECTIVE: To identify K+ channels of smooth muscle of human umbilical artery using the patch-clamp technique and to study their effect on resting tone of umbilical artery rings. METHODS: Whole-cell and single-channel patch-clamp recordings in enzymatically isolated smooth muscle cells were made. Measurements of developed isometric force were performed on intact tissue. RESULTS: Delayed rectifier K+ channels (KDR) and large-conductance Ca2+-activated K+ channels (BKCa) contribute to the whole-cell voltage- and time-dependent outward K+ current, as it was specifically inhibited by 5 mM 4-aminopyridine (4-AP; KDR blocker) (92 +/- 4% at 0 mV, n = 7), by 1 mM tetraethylammonium (TEA; BKCa blocker) (71 +/- 4% at +60 mV, n = 4), and by 200 nM iberiotoxin (BKCa blocker) (64 +/- 7% at +60 mV, n = 4). In outside-out patches, BKCa channels had a single-channel conductance of 132 +/- 4 pS (n = 24) in asymmetric K+ conditions and 216 +/- 4 pS (n = 4) in a symmetric K+ gradient. The activity of the BKCa channels was significantly augmented by 1 microM Ca2+ in the inside-out configuration. 4-AP had no effect on resting tone of intact arterial rings. TEA produced contraction of arterial rings whereas phloretin, an activator of BKCa, relaxed them, which means that BKCa channels are functional in intact tissue and are involved in the maintenance of resting tone in this human vessel. CONCLUSION: The identities of K+ channels in the human umbilical artery were shown using the patch-clamp technique, and the physiologic effect of K+ channels on resting tone was documented.

Diversity of potassium channels in human umbilical artery smooth muscle cells: a review of their roles in human umbilical artery contraction.

Through their control of cell membrane potential, potassium (K(+)) channels are among the best known regulators of vascular tone. This article discusses the expression and function of K(+) channels in human umbilical artery smooth muscle cells (HUASMCs). We review the bibliographic reports and also present single-channel data recorded in freshly isolated cells. Electrophysiological properties of big conductance, voltage- and Ca(2+)-sensitive K(+) channel and voltage-dependent K(+) channels are clearly established in this vessel, where they are involved in contractile state regulation. Their role in the maintenance of membrane potential is an important control mechanism in the determination of the vessel diameter. Additionally, small conductance Ca(2+)-sensitive K(+) channels, 2-pore domains K(+) channels and inward rectifier K(+) channels also appear to be present in HUASMCs, while intermediate conductance Ca(2+)-sensitive K(+) channels and ATP-sensitive K(+) channels could not be identified. In both cases, additional investigation is necessary to reach conclusive evidence of their expression and/or functional role in HUASMCs. Finally, we discuss the role of K(+) channels in pregnancy-related pathologies like gestational diabetes and preeclampsia.

Bupivacaine inhibits large conductance, voltage- and Ca2+- activated K+ channels in human umbilical artery smooth muscle cells.

Bupivacaine is a local anesthetic compound belonging to the amino amide group. Its anesthetic effect is commonly related to its inhibitory effect on voltage-gated sodium channels. However, several studies have shown that this drug can also inhibit voltage-operated K(+) channels by a different blocking mechanism. This could explain the observed contractile effects of bupivacaine on blood vessels. Up to now, there were no previous reports in the literature about bupivacaine effects on large conductance voltage- and Ca(2+) -activated K(+) channels (BK(Ca)). Using the patch-clamp technique, it is shown that bupivacaine inhibits single-channel and whole-cell K(+) currents carried by BK(Ca) channels in smooth muscle cells isolated from human umbilical artery (HUA). At the single-channel level bupivacaine produced, in a concentration- and voltage-dependent manner (IC(50) 324 µM at +80 mV), a reduction of single-channel current amplitude and induced a flickery mode of the open channel state. Bupivacaine (300 µM) can also block whole-cell K(+) currents (~45% blockage) in which, under our working conditions, BK(Ca) is the main component. This study presents a new inhibitory effect of bupivacaine on an ion channel involved in different cell functions. Hence, the inhibitory effect of bupivacaine on BK(Ca) channel activity could affect different physiological functions where these channels are involved. Since bupivacaine is commonly used during labor and delivery, its effects on umbilical arteries, where this channel is highly expressed, should be taken into account.

Educación en salud a través del desarrollo de habilidades científicas en escolares chilenos / Health education trough the development of scientific skills in Chilean schools

Resumen: Objetivo: Describir los intereses, preferencias temáticas y aprendizajes en el campo de la salud pública que emergen de escolares chilenos tras una experiencia de indagación científica escolar. Material y métodos: Estudio exploratorio de carácter cualitativo, realizado en 29 grupos de investigación escolar del proyecto Salud Con-Ciencia en tu Barrio, basado en un análisis de contenido de textos y narrativas de los estudiantes. Resultados: Los estudiantes priorizan la situación de animales abandonados, el manejo de la basura y la seguridad e infraestructura urbana visualizando el rol de los actores sociales y el impacto positivo/negativo en la comunidad, y valorando el conocimiento obtenido a través de la observación de barrios e interacción con vecinos. Conclusiones: La indagación científica escolar en el contexto barrial aporta estrategias didácticas para la promoción de la salud local y desarrolla nociones básicas de salud comuntaria y motivación en los estudiantes por vincularse con la realidad socioambiental de sus barrios.

Abstract: Objective: To describe the interests, preferred topics and learning in public health issues emerging from Chilean students with their participation in a science education experience. Materials and methods: A qualitative exploratory study was conducted in 29 school research groups through the project Salud Con-Ciencia en tu Barrio, based on a content analysis of texts and narratives of students. Results: Students prioritize the situation of abandoned animals, waste management, security and urban infrastructure, mainly. They view the role of social actors, the positive/negative impacts on the community, valuing the knowledge gained through observation neighborhoods and interaction with neighbors. Conclusions: Scientific inquiry school in the neighborhood context provides teaching strategies for the promotion of local health, develops basic notions of community health and motivation in students linked to the socio-environmental reality of their neighborhoods.

Risperidone inhibits contractions induced by serotonin and histamine and reduces K+ currents in smooth muscle of human umbilical artery.

Risperidone is an antipsychotic commonly used during pregnancy. Because it can cross the placental barrier, our objective was to evaluate its actions on the smooth muscle of the human umbilical artery (HUA). Risperidone preincubation (1-300 nmol/L for 20 minutes) produced a significant decrease in maximum force development induced by serotonin or histamine in HUA rings. When applied on top of stable contractions induced by these agonists risperidone produced quick relaxations (IC(50) = 1 nmol/L for serotonin and 72 nmol/L for histamine). Risperidone induced the contraction of vascular rings depolarized by 40 mmol/L extracellular K(+) but not in the case of 80 mmol/L K(+), suggesting inhibition of K(+) channels. The patch-clamp technique showed that risperidone (3 nmol/L) inhibited whole-cell K(+) currents in freshly isolated HUA smooth muscle cells. Our results are the first showing risperidone effects in human vascular smooth muscle and highlight that its use during pregnancy should be adequately monitored.

L, P-/Q- and T-type Ca2+ channels in smooth muscle cells from human umbilical artery.

The electrophysiological and pharmacological properties of Ca(2+) current (I(Ca)) were determined by the whole-cell configuration of the patch-clamp technique in smooth muscle cells from human umbilical artery. Using 5 mM extracellular Ca(2+), depolarizing step pulses from -60 to 50 mV from a holding membrane potential of -80 mV evoked an I(Ca) which activated at membrane potentials more positive than -50 mV and exhibited a maximum current density in a range of 10-20 mV. Steady-state inactivation protocols using a V(test) of 10 mV gave a voltage at one-half inactivation and a slope factor of -35.6 mV and 9.5 mV, respectively. Nifedipine (1 microM), an L-type Ca(2+) channels antagonist, completely inhibited I(Ca), while the L-type Ca(2+) channels agonist Bay-K 8644 (1 microM) significantly increased I(Ca) amplitude. Moreover, the selective blocker of P-/Q-type Ca(2+) channels omega-agatoxin IVA partially blocked I(Ca) (about 40 % inhibition at +20 mV by 20 nM). These pharmacological results suggest that L- and P-/Q-type Ca(2+) channels, both nifedipine-sensitive, underlie the I(Ca) registered using low extracellular Ca(2+). The presence of the P-/Q-type Ca(2+) channels was confirmed by immunoblot analysis. When I(Ca) was recorded in a high concentration (30 mM) of extracellular Ca(2+) or Ba(2+) as current carrier, it was evident the presence of a nifedipine-insensitive component which completely inactivated during the course of the voltage-step (75 ms) at all potentials tested, and was blocked by the T-type Ca(2+) channels blocker mibefradil (10 microM). Summarizing, this work shows for the first time the electrophysiological and pharmacological properties of voltage-activated Ca(2+) currents in human umbilical artery smooth muscle cells.

Human umbilical artery smooth muscle exhibits a 2-APB-sensitive capacitative contractile response evoked by vasoactive substances and expresses mRNAs for STIM, Orai and TRPC channels

After depletion of intracellular Ca2+ stores the capacitative response triggers an extracellular Ca2+ influx through store-operated channels (SOCs) which refills these stores. Our objective was to explore if human umbilical artery smooth muscle presented this response and if it was involved in the mechanism of serotonin- and histamine-induced contractions. Intracellular Ca2+ depletion by a Ca2+-free extracellular solution followed by Ca2+ readdition produced a contraction in artery rings which was inhibited by the blocker of Orai and TRPC channels 2-aminoethoxydiphenyl borate (2-APB), suggesting a capacitative response. In presence of 2-APB the magnitude of a second paired contraction by serotonin or histamine was significantly less than a first one, likely because 2-APB inhibited store refilling by capacitative Ca2+ entry. 2-APB inhibition of sarcoplasmic reticulum Ca2+ release was excluded because this blocker did not affect serotonin force development in a Ca2+-free solution. The PCR technique showed the presence of mRNAs for STIM proteins (1 and 2), for Orai proteins (1, 2 and 3) and for TRPC channels (subtypes 1, 3, 4 and 6) in the smooth muscle of the human umbilical artery. Hence, this artery presents a capacitative contractile response triggered by stimulation with physiological vasoconstrictors and expresses mRNAs for proteins and channels previously identified as SOCs.

Effects of light ethanol consumption during pregnancy: increased frequency of minor anomalies in the newborn and altered contractility of umbilical cord artery.

This study explores the effects of light maternal ethanol consumption during pregnancy on the appearance of minor malformations in neonates as well as on the contractile properties of their umbilical cord arteries (UCAs). Clinical external findings of newborns of women declaring light ethanol consumption during any period of their pregnancies [ethanol-exposed group (E group), n=79] were compared with those of nonexposed mothers [nonexposed to ethanol group (NE group), n=100]. Women who smoked or had any associated pathology were excluded. E group mothers consumed, on average, 200-250 mL ethanol/trimester (upper limit 700 mL/trimester). Sixty-six percent of the neonates in the E group presented at least one minor malformation (retromicrognathia and minor anomalies of the auricular/preauricular area were the more common), whereas only 16% of the NE group did (p=0.0000). The percentage of children exhibiting Apgar scores <7 was significantly greater in the E group (11% versus 2%, p=0.0119). UCAs from the E group developed significantly less contractile force (p<0.05) than those of the NE group when exposed to 1 microM serotonin (5-HT) or to a high K+ depolarizing solution. This difference persisted after inhibition of endothelial release of nitric oxide (NO) and prostacyclin. In conclusion, even light drinking should be considered a risk during pregnancy.

Tabaquismo materno: impacto sobre el neonato, placenta y reactividad de la arteria umbilical / Maternal smoking: its impact on the newborn: the placenta and the reactivity of the human umbilical artery

El fumar tabaco durante el embarazo aumenta los riesgos en la salud materno-infanto juvenil provocando múltiples alteraciones atribuidas a la nicotina y al monóxido de carbono producidos por el cigarrillo.

Efectos de la insulina sobre la respuesta contractil y la captacion de calcio en aorta de rata / Effect of insulin on contractile response and calcium captation in rat aorta

La insulina afecta mecanismos fisiológicos generales que regulan la presión arterial, y a nivel celular modifica las funciones del endotelio y del mosculo liso vascular, que son determinantes de la resistencia periférica. Describimos los efectos de la preincubación con insulina (40 muU/ml, durante 1-2 hs) sobre la reactividad contráctil de anillos intactos de aorta de rata y sobre la captaci>n de 45Ca2+ en segmentos de aorta de rata hipermeabilizados por tratamiento con EGTA. La preincubación con insulina no afectó las contracciones inducids por 1 muM de NA, ni la relajación de las mismas inducida por 10 mM de cafeína. La respuesta contractil a 1 muM de Ang-II (que en la aorta de rata es independiente de endotelio) fue estimulada por la preincubación con insulina en la fuerza máxima desarrollada y en la velocidad de relajación espontánea de la contracción. La diferencia en la captación de 45Ca2+ en RS entre los segmentos de aorta tratados y no tratados con insulina fue mayor a los 5 minutos con respecto a la medida a los 30 minutos. Se concluye que la preincubación con insulina afecta en forma directa la respuesta mecánica del mosculo liso aórtico estimulado con Ang-II y se propone a la modificación de la actividad del RS como uno de los mecanismos mediante el cual la insulina participa en la regulación del Ca2+ citosólico.

Insulina, reatividad valcular me hipertension arterial / Insulin, vascular reactiviry and hypertension

Varios estudios epidemiológicos indican que hay una relación entre hiper-insulinemia, resistencia insulínica e hipertensión arterial. La insulina estimula el sistema nervioso simpático, produce retención renal de Na+ y modifica en forma directa mecanismos vasculares (contrayentes y relajantes); estos efectos pueden justificar que la insulina aumente o disminuya la presión arterial. la ausencia de los efectos vasodilatadores debido a resistencia insulínica y/o la mayor manifestación de los efectos hipertensores en caso de hiperinsulinemia podrían ser el nexo entre la insulina y la hipertensión arterial.

Chronotropic, inotropic and lusitropic effects of capsaicin on isolated rat Atria

This work includes results on chronotropic, inotropic and lusitropic changes induced by capsaicin on isolated rat atria. As regards spontaneous frequency, it was stimulated from 10(-9) M up to 7 x 10(-7) M of capsaicin. A simultaneous depression in developed force (F) showed a signigicant correlation with this positive chronotropic effect up to 7 X 10(-8) M of capsaicin, which is the result of the negative staircase phenomenon in the rat heart. The correlation was lost at 2 and 7 x 10(-7) M of capsaicin since in spite of the sustained increase in atrial rate the decrease in F was reversed and then depressed again at 2 and 7x 10(-6) M of capsaicin without changes in frequency. A concentration of capsaicin that overcome the negative staircase phenomenon, 5 x 10(-7) M, was tested as unique dose resulting in stimulation of the chronotropic, inotropic and lusitropic states of the atria. Percentual differences with respect to control values were maximal after 1-3 minutes for frequency (10+3 per cent), F (29+4 per cent), maximal velocity of force development (+F=50+12 per cent) (in all cases +F and -F,bold indicates +F and -F, respectively) and maximal velocity of relaxation (-F=64+13 per cent); a positive lusitropic effect was significant after 8-10 minutes (+F/-F=-17+7 per cent). Capsaicin did not affect the rat atria in the presence of 10(-6) M of ruthenium red, a blocker of capsaicin activation of sensory nerves, indicating that the stimulatory effects were entirely mediated by the release of neurotransmitters and that this concentration of capsaicin was not deleterous "per se". Capsaicin elicited similar inotropic responses in electrically driven isolated atria (+F=41+9 per cent) but the positive lusitropic effect was lost suggesting that capsaicin-induced increases in -F are limited at a frequency higher than the spontaneous frequency (11+6 vs. 32+4 per cent, respectively). 10(-6) M of CGRP8(-37), an antagonist of CGRP1 receptors, suppress the stimulatory effects of capsaicin on atrial contraction. In summary, atrial rate as compared to atrial contraction is more sensitive to the neurotransmitter released by capsaicin, which results in mechanical effects expressing the negative staircase phenomenon in the rat at low concentrations of capsaicin. The positive chronotropic, inotropic and lusitropic responses elicited by capsaicin are mediated by the reelease of neurotransmitters from sensory fibbers and no deletereous effects...