Purinergic Signaling During Hyperglycemia in Vascular Smooth Muscle Cells

The activation of purinergic receptors by nucleotides and/or nucleosides plays an important role in the control of vascular function, including modulation of vascular smooth muscle excitability, and vascular reactivity. Accordingly, purinergic receptor actions, acting as either ion channels (P2X) or G protein-coupled receptors (GCPRs) (P1, P2Y), target diverse downstream effectors, and substrates to regulate vascular smooth muscle function and vascular reactivity. Both vasorelaxant and vasoconstrictive effects have been shown to be mediated by different purinergic receptors in a vascular bed- and species-specific manner. Purinergic signaling has been shown to play a key role in altering vascular smooth muscle excitability and vascular reactivity following acute and short-term elevations in extracellular glucose (e.g., hyperglycemia). Moreover, there is evidence that vascular smooth muscle excitability and vascular reactivity is severely impaired during diabetes and that this is mediated, at least in part, by activation of purinergic receptors. Thus, purinergic receptors present themselves as important candidates mediating vascular reactivity in hyperglycemia, with potentially important clinical and therapeutic potential. In this review, we provide a narrative summarizing our current understanding of the expression, function, and signaling of purinergic receptors specifically in vascular smooth muscle cells and discuss their role in vascular complications following hyperglycemia and diabetes

Motilidad gastrointestinal en ratas: ¿una práctica de laboratorio adecuada para estudiantes de medicina?

In this study, the feasibility of establishing, as a regular lab practice for second year medical students taking the Human Physiology course, the recently published “hands on” activity by Souza et al. ( 2002), to assess gastrointestinal motility in awake rats, was determinate. The gastric emptying and the intestinal motility were evaluated in three different times after administering a hypertonic bolus or under hypoglycemia conditions, by the method of phenol red dye fractional recovery in the stomach and in the proximal, middle and distal portions of the small intestine of male Wistar rats. Significant differences in the gastric emptying between the hypertonic group and the control group were found only 20 min after the injection of the bolus (53.8 ± 7.4 vs 25.5 ± 3.0. p<0.05). However the hypoglycemic group did not show differences versus the control group at any time. Under experimental conditions of our work, the hypertonic bolus does delay the gastric emptying but not intestinal motility, whereas the hypoglycemia does not modify either the gastric emptying or the intestinal motility. Although illustrative and adequate to establish as a discussion activity in the group, this lab practice is technically difficult to carry out in less of 5 h.Se determinó la viabilidad de establecer, como una práctica regular de laboratorio para estudiantes del segundo año de medicina que toman el curso de Fisiología Humana, la actividad “manual” publicada recientemente por Souza et al. (2002), para analizar la motilidad gastrointestinal en ratas despiertas. Se evaluaron el vaciamiento gástrico y la motilidad intestinal a tres diferentes tiempos después de administrar un bolo hipertónico o bajo condiciones de hipoglucemia, por el método de recuperación fraccional del colorante rojo de fenol en el estómago y en las porciones proximal, media y distal del intestino de ratas Wistar macho. Se encontraron diferencias significativas en el vaciamiento gástrico entre el grupo hipertónico y el control sólo a los 20 min después de la inyección del bolo (53.8 ± 7.4 vs 25.5 ± 3.0. p<0.05). Sin embargo, el grupo de hipoglucemia no mostró diferencias con el grupo control en ningún momento. En las condiciones experimentales de nuestro trabajo, el bolo hipertónico retarda el vaciamiento gástrico pero no la motilidad intestinal, mientras que la hipoglucemia no modifica ni el vaciamiento gástrico ni la motilidad intestinal. Aunque demostrativa y adecuada para establecer la discusión con los estudiantes esta práctica de laboratorio es técnicamente difícil de efectuar en menos de 5 horas

[Ca2+]i changes in guinea pig tracheal smooth muscle cells in culture: effects of Na+ and ouabain

The objective of this work was to confirm that the contractile effects of ouabain and Na+-free solutions in guinea pig tracheal rings are associated with increments in the cytosolic free Ca2+ concentration ([Ca2+]i) in cultured tracheal smooth muscle (TSM) cells. Cultured cells were a-actin positive. Histamine (50 mM) and Na+ -free solution elicited a transient increase in [Ca2+]I, while the responses to thapsigargin (1 µM) and ouabain (1 mM) were long lasting. However, carbachol (10, 200, and 500 mM) and high K+-solution produced no effect on [Ca2+]i, suggesting that cultured guinea pig TSM cells display a phenotype change but maintain some of the tracheal rings physiological properties. The transient rise in [Ca2+]i in response to the ce of extracellular Na+ and the effect of ouabain may indicate the participation of the Na+/Ca2+ exchanger (NCX) in the regulation of [Ca2+]i.El objetivo del presente trabajo es el de confirmar que los efectos contráctiles producidos por la ouabaína y la ausencia de Na+ en la solución en anillos de traquea de cobayo, se asocian a incrementos en la concentración libre de Ca2+ citosólico ([Ca2+]i) en células cultivadas de músculo liso traqueal de cobayo. Las células usadas en los experimentos eran positivas para a-actina de músculo liso. La histamina (50 µM) y las soluciones libres de Na+ producen un incremento transitorio en la [Ca2+]i mientras que la thapsigargina (1 µM) y la ouabaína (1 mM) dan lugar a incremento de larga duración. Sin embargo, el carbacol (10, 200 y 500 µM) y soluciones con alta concentración de K+ no producen cambios en la [Ca2+]i . Estos resultados sugieren que, en nuestras condiciones experimentales, las células cultivadas de músculo liso traqueal presentan cambios en su fenotipo, pero conservan algunas de las propiedades fisiológicas observadas en los anillos traqueales. El incremento transitorio de la [Ca2+]i producido por la ausencia de Na+ extracelular y el efecto de la ouabaína sugieren la participación del intercambiador Na+/Ca2+ (NCX) en la regulación de la [Ca2+]i

Fatty Acid-Binding Proteins Identification during the Evolution of Metabolic Syndrome: A Raman Spectroscopy-Based Approach

Excess fat in abdominal deposits is a risk factor for multiple conditions, including metabolic syndrome (MetS); lipid metabolism plays an essential role in these pathologies; fatty acid-binding proteins (FABPs) are dedicated to the cytosolic transport of fat. FABP4, whose primary source is adipose tissue, is released into the circulation, acting as an adipokine, while FABP5 also accompanies the adverse effects of MetS. FABP4 and 5 are potential biomarkers of MetS, but their behavior during syndrome evolution has not been determined. Raman spectroscopy has been applied as an alternative method to disease biomarker detection. In this work, we detected spectral changes related to FABP4 and 5 in the serum at different points of time, using an animal model of a high-fat diet-induced MetS. FABP4 and 5 spectral changes show a contribution during the evolution of MetS, which indicates alteration to a molecular level that predisposes to established MetS. These findings place FABPs as potential biomarkers of MetS and Raman spectroscopy as an alternative method for MetS assessment