Vasoreactivity of the Murine External Jugular Vein and Carotid Artery

Abstract

Few studies have characterized vasoreactivity of the murine external jugular vein. This segment often is used in preclinical models to evaluate vascular remodeling in response to arteriovenous fistula (AVF) maturation. When an AVF is established, the venous segment is exposed to arterial pressures and disturbed flow patterns that have strong potential to impact vasoreactivity. Before testing this hypothesis in the context of AVF, we sought to establish procedures to comprehensively characterize endothelium‐dependent and vascular smooth muscle function of the carotid artery and external jugular vein from healthy mice. External jugular veins and ipsilateral common carotid arteries were isolated from five‐month‐old male C57BL/6 mice and vasomotor responses were evaluated using isometric tension procedures. External jugular veins developed tension (p<0.05) to the voltage‐gated Ca2+ channel opener potassium chloride (KCl) and the thromboxane A2 receptor agonist U‐46619, but not to the α‐1 receptor agonist phenylephrine (PE), whereas common carotid arteries responded to all three vasocontractile agents in a more robust (p<0.05) manner. While maximal responses (~70%) to the endothelium‐dependent vasodilator acetylcholine (ACh) were similar between the venous and arterial segments, the dose required to achieve this value was lower (p<0.05) in the artery versus the vein. Nitric oxide synthase (NOS) inhibition using L‐NMMA attenuated (p<0.05) but did not abolish ACh‐evoked vasorelaxation in both vascular segments. Endothelium‐independent vasorelaxation to sodium nitroprusside (SNP) was similar in the artery and the vein. Endothelium‐dependent and vascular smooth muscle function can be reliably assessed in the murine external jugular vein of healthy male C57Bl/6 mice. Compared to common carotid arteries, external jugular veins are resistant to PE‐evoked vasocontraction, less responsive to KCl and U‐46619‐evoked vasocontraction, less sensitive to ACh‐evoked vasorelaxation, and equally responsive to NOS inhibition and guanylate cyclase activation via SNP. Ongoing studies will determine if and how external jugular vein function is altered by arterial pressures and disturbed flow patterns that are encountered subsequent to establishing an AVF.Support or Funding InformationJMC (University of Utah Graduate Research Fellowship); YTS (R01DK100505; I01BX004133); JDS (AHA16GRNT31050004, NIH RO3AGO52848, RO1HL141540); TL (R44DK109789, R01HL139692, I01BX003387).