Flow mediated dilation variation based on normotensive rat strain

Abstract

Previous studies from this lab have suggested that nitric oxide (NO) plays a significant role in the maintenance of arterial pressure in the same strain of rats obtained from different animal vendors. Subsequently, we hypothesized that similar variations in NO and thus, endothelial function, could be found in different strains of rat. Flow mediated dilation (FMD) is traditionally a non‐invasive technique used clinically to assess endothelial function. The hyperemic response elicited using this in vivo technique is thought to be mediated by NO release from the endothelium. The goal of the present study was to determine whether the FMD hyperemic response was different between two normotensive strains from the same supplier, Sprague‐Dawley (SD) and Wistar‐Kyoto rats (WKY) from Charles River (CR). In anesthetized rats, the femoral artery was isolated and occluded for 5 minutes, with femoral blood flow measured continuously before, during and after occlusion by use of an ultrasonic perivascular flow probe. Arterial pressure was measured directly via a catheter inserted into the contralateral femoral artery. The clamp procedure was repeated four times in each rat and then averaged. The average area under the FMD response curve (3 minute duration) for the CR SD rats was 79.0 ± 22.9 mL/min·s (n=6) and 371.0 ± 67.4 mL/min·s (n=5) for the CR WKY rats. These results suggest differences in endothelial function in normotensive rats and could have broad implications for research involving these strains of rat.