Resumen de Diferencias en la respuesta in vitro ante agentes vasoactivos, entre anillos de arterias y venas digitales palmares de equinos

Héctor Zerpa, Félix Vega, José Vásquez, Elías Ascanio, Gerardo Campos A., Elias Sogbe M., Eduardo Romero, Herakles A García, Marisela Ascanio

• español

  El flujo sanguíneo del casco de los equinos depende de la presión de perfusión y de la resistencia vascular; estas variables pueden ser afectadas por variaciones en el diámetro vascular. El objetivo del trabajo fue comparar la respuesta vascular in vitro ante agentes vasoactivos, de los anillos de arterias y venas digitales palmares de equinos mestizos. Los anillos vasculares se obtuvieron a través de cirugía bajo anestesia general (xilazina-ketaminahalotano). Estos se incubaron en baños de órgano aislado a 37 ºC en 20 ml de solución de Krebs (O2 95%, CO2 5%) bajo tensión basal de 2 g y equilibrados por 1 hora. Se registró la reactividad vascular con transductor isométrico acoplado a un polígrafo NarcoBiosystem

• English

  The equine hoof blood flow depends on perfusion pressure and vascular resistance. Changes in the vessel lumen may affect these variables. The aim of this study was to compare the vascular response to vasoactive agents between equine digital palmar arteries and vein rings. Crossbreed horses were used. Vascular rings were harvested by surgical procedures under general anaesthesia (xylazine-ketaminehalotane). Rings were incubated in a 20 ml isolated organ bath containing Krebs solution (O2 95%, CO2 5%) at 37 ºC.

  The rings were equilibrated for 1 h with 2 g of basal tension and contractions were recorded with an isometric transducer in a NarcoBiosystem polygraph. After the equilibration period the contractil response to KCl 40 mM solution was determined. Then dose response curves to phenylephryne (Phe), acethylcholine (ACh) and sodium nitroprusside (SNP) were performed. The last ones after Phe vascular preconstriction. KCl maximal contraction (MC) was similar between arteries and veins rings, MC to Phe was significantly higher in veins compared to arteries (1156 vs 645.8 mg/mg, p<0.05) with a higher pD2 (negative logarithmic of 50 effective dose) to Phe for arteries (5.92 vs 5.7). ACh maximal relaxation (MR) was significantly higher in arteries vs veins (55.91% vs 46.5%, p<0.05) but MR to SNP was higher in veins compared to arteries (73.20% vs 65.01%, p=0.054).

  The different MC response to Phe may suggest the presence of a receptor distribution heterogeneity with different receptor reserve in smooth muscle (SM) in both vascular beds. Veins SM higher response capability probably can be linked to an active role on venous return from the equine limbs. ACh an SNP responses are similar to the ones reported in other species in which arterial endothelium shows a higher nitric oxide production and veins SM shows a higher response to direct nitrosithiols do