Baseline plasmaccholinesterase activities in argentine saddle horses from sabana deboogotá / Activdad colinessterasa plasmática en caballos silla Argentina de la sabana de bogotá

The determination of cholinesterase (ChE) activity in domestic animals is of great importance for diagnosis and research purposes. The present work was aimed to determine the baseline plasma ChE activities (acetylcholinesterase, AChE and butyrylcholinestarase, BChE) of Argentine saddle horses sampled from equine farms of Bogota (Colombia) and its surroundings. Plasma AChE and BChE catalytic activities were measured in 60 healthy horses by spectrophotometry within the visible spectrum (405 nm). AChE mean ± SD values (nmols/ml/min) for males (n=32) were 1566 ± 301. Age intervals results were, 0.5-5 years: 1526 ± 295, 6-10 years: 1532 ± 313, 11-15 years: 1615 ± 279, and > 15 years: 1617 ± 335. As for females (n=28), mean AChE was 1323 ± 432, with age intervals as follows, 0.5-5 years: 719 ± 108, 6-10 years: 1603 ± 313, 11-15 years: 1225 ± 294, > 15 years: 1519 ± 369. BChE in males were 3304 ± 822; with age intervals, 0.5-5 years: 3383 ± 715, 6-10 years: 3360 ± 766, 11-15 years: 3267 ± 1064, > 15 years: 3206 ± 861. As for females, BChE values were 3097 ± 432, with age intervals: 0.5-5 years: 2467 ± 981, 6-10 years: 3668 ± 750, 11-15 years: 3238 ± 979, and > 15 years: 3015 ± 925. AChE was significantly different between males and females (t test, p < 0.05) and for both genders when age groups were compared (ANOVA, p < 0.05). BChE had higher values than AChE for both genders and yet no significant difference was found when genders were compared. No differences were found in BChE for age groups in both genders. In a second test, 15 random samples, kept at 4 ºC for 72 hours, were analyzed for variations when measured every 24h. Neither AChE nor BChE had significant variations in these 24h-apart measurements. The present investigation found baseline activities for the two types of plasma cholinesterases in Argentinian saddle horses. This will allow researchers and clinicians to count on reference values for diagnosis and comparative purposes.

La determinación de la actividad colinesterasa (ChE) en animales domésticos es de importancia en diagnóstico e investigación. El presente trabajo tuvo como objetivo principal la determinación de la línea base de actividad ChE plasmática (acetilcolinesterasa, AChE y butirilcolinesterasa, BChE) en 60 caballos Silla Argentino muestreados en fincas de equinos ubicadas en Bogotá (Colombia) y sus alrededores. Las actividades catalíticas de AChE y BChE plasmáticas fueron medidas mediante espectrofotometría visible (405 nm). Los valores promedio ± desviación estándar de actividad AChE (nmols/ml/ min) para machos (n=32) fueron 1566 ± 301. En intervalos de edad, los resultados fueron, 0.5-5 años: 1526 ± 295, 6-10 años: 1532 ± 313, 11-15 años: 1615 ± 279, y > 15 años: 1617 ± 335. En hembras (n=28), la actividad AChE fue 1323 ± 432, con valores en intervalos de edad, 0.5-5 años: 719 ± 108, 6-10 años: 1603 ± 313, 11-15 años: 1225 ± 294, > 15 años: 1519 ± 369. La BChE en machos fue 3304 ± 822; con intervalos de edad, 0.5-5 años: 3383 ± 715, 6-10 años: 3360 ± 766, 11-15 años: 3267 ± 1064, > 15 años: 3206 ± 861. En hembras, la BChE fue 3097 ± 432, con intervalos de edad: 0.5-5 años: 2467 ± 981, 6-10 años: 3668 ± 750, 11-15 años: 3238 ± 979, y > 15 años: 3015 ± 925. La actividad AChE fue significativamente diferente entre machos y hembras (test t, p < 0.05) y en ambos géneros al comparar los grupos etáreos (ANAVA, p < 0.05). BChE tuvo valores más altos que AChE, sin embargo, no en forma significativa cuando se compararon los resultados entre los dos géneros, ni cuando se compararon los grupos etáreos en los dos géneros. En una prueba adicional, 15 muestras fueron tomadas al azar y mantenidas a 4ºC durante 72 horas para ser analizadas cada 24 horas; AChE y BChE no mostraron variaciones significativas entre las mediciones hechas en este período de tiempo. El presente estudio permitió determinar lineas base de los dos tipos de colinesterasas plasmáticas en caballos tipo silla Argentino con el propósito de ofrecer valores de referencia con fines diagnósticos y comparativos para clínicos e investigadores.

Leishmania amazonensis infection induces changes in the electrophysiological properties of macrophage-like cells.

Whole cell patch-clamp recordings were used to study the electrical properties of the macrophage-like cell line J774.1, after infection with Leishmania amazonensis. Infection induced a significant increase in cell size and membrane capacitance, suggesting that parasite invasion leads to the addition of plasma membrane to the host cell. By 24 hr after infection, the host cell membrane potential was significantly more hyperpolarized than control cells, and this difference remained for the subsequent 72 hr post-infection. The hyperpolarization was paralleled by an increase in the density of inward rectifying K(+) currents. The shape of the conductance vs. voltage curve, the kinetic properties and the pharmacological profile of these currents were not significantly altered by infection. These results suggest that infection by L. amazonensis causes an increase in the number of functional inward rectifying K(+) channels, leading to hyperpolarization of the host cell membrane.

Two different conductances contribute to the anion currents in Coffea arabica protoplasts.

The anion conductance of the plasma membrane of Coffea arabica protoplasts was isolated and characterized using the whole-cell patch clamp technique. Voltage pulse protocols revealed two components: a voltage-gated conductance (Gs) and a voltage-independent one (Gl). Gs is activated upon depolarization (e-fold activation every +36 mV) with time constants of 1 sec and 5 sec at all potentials. Gl and Gs also differ by their kinetic and biophysical properties. In bi-ionic conditions the current associated with Gs shows strong outward rectification and its permeability sequence is F- > NO3- > Cl-. In the same conditions the current associated with Gl does not rectify and its permeability sequence is F- > > NO3- = Cl-. Furthermore, at potentials over +50 mV Gs, but not Gl, increases with a time constant of several minutes. Finally the gating of Gs is affected by stretch of the membrane, which leads to an increased activation and a reduced voltage sensitivity. Anion conductances similar to the ones described here have been found in many plant preparations but Gl-type components have been generally interpreted as the background activation of the slow voltage-gated channels (corresponding to Gs). We show that in coffee protoplasts Gl and Gs are kinetically and biophysically distinct, suggesting that they correspond to two different molecular entities.