The vascular glycocalyx is not a mechanosensor in conduit arteries in the anesthetized pig.

The role of the glycocalyx as the endothelial sensor of an increase in blood flow was assessed in the iliac artery in vivo. Acetylcholine-induced flow mediated dilation was evaluated before and after vascular glycocalyx disruption. This was accomplished by exposing the iliac lumen to the chemotactic agent fMLP (1 μM; = 6 pigs), concomitant heparinase III (100 mU ml) and hyaluronidase (14 mg ml) ( = 4), and neuraminidase (140 mU ml; = 5), for 20 min in separate iliac artery preparations. Only one lumen intervention per iliac was conducted. For the heparinase III + hyaluronidase experiment, the iliac diameter increased by an average of 0.54 ± 0.11 mm before and 0.45 ± 0.03 mm after the enzymes ( = 0.42; paired Student's test). The iliac diameter increased by 0.31 ± 0.02 mm before and 0.29 ± 0.07 mm after fMLP exposure ( = 0.7) and the diameter increased by 0.54 ± 0.11 mm before and 0.54 ± 0.09 mm after neuraminidase exposure ( = 0.98). In all cases, the shear stress changes before and after lumen exposure were not significantly different to each other. There was no significant reduction in flow mediated dilation of the iliac in response to any of the interventions conducted. Therefore, the vascular endothelial glycocalyx as whole is not required for flow mediated dilation in conduit arteries in the intact animal

Heparan sulphate and hyaluronic acid components of the glycocalyx do not play a role in flow-mediated dilation of the iliac in the anaesthetized pig

The shear-stress sensor function of vascular glycocalyx heparan sulphate and hyaluronic acid was investigated in vivo by assessing flow-mediated dilation before and after their removal. Heparinase III exposure (100 mU·mL−1 for 20 min;n = 6) did not significantly affect flow-mediated dilation of the iliac, from 0.42 ± 0.08 mm (mean ± SEM) to 0.34 ± 0.07 mm after (P = 0.12; paired Student’s t test) for a statistically similar increase in shear stress; 18.24 ± 4.2 N·m−2 for the control and 15.8 ± 3.6 N·m−2 for the heparinase III experiment (P = 0.18). Hyaluronidase exposure (0.14–1.4 mg·mL−1 for 20 min; n = 8) also did not significantly reduce flow-mediated dilation of the iliac, which averaged 0.39 ± 0.08 mm before and 0.38 ± 0.09 mm after (P = 0.11) for a statistically similar increase in shear stress; 11.90 ± 3.20 N·m−2 for the control and 9.8 ± 3.33 N·m−2 for the hyaluronidase experiment (P = 0.88). Removal of both heparan sulphate and hyaluronic acid was confirmed using immunohistochemistry. Neither the heparan sulphate nor the hyaluronic acid components of the glycocalyx mediate shear-stress-induced vasodilation in conduit arteries in vivo.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Assessment of renal function in the anaesthetised rat following injection of superparamagnetic iron oxide nanoparticles

A recent study showed that a significant fall in mean arterial pressure (MAP) occurred following intravenous injection of two novel superparamagnetic iron oxide nanoparticles (SPIONs), MF66 and OD15. To assess if this was caused by excessive glomerular clearance, the effect of both particles on renal function was studied. Experiments were performed on sodium pentobarbital anaesthetised male Wistar rats (250?350 g). Twenty-minute urine clearances were taken followed by an i.v. bolus of MF66, OD15 (2 mg?kg?1), or dH2O (0.4 mL?kg?1). MF6 or OD15 injection resulted in a significant transient drop in MAP and renal blood flow by approximately 33% and 50% (P < 0.05). The absolute excretion of sodium was significantly increased (P < 0.05) by almost 80% and 70% following OD15 and MF66, respectively. Similarly, fractional excretion of sodium was increased by almost 80% and 60% following OD15 and MF66, respectively. The glomerular filtration rate was not significantly affected, but urine flow increased nonsignificantly by approximately 50% and 66% following i.v. injection of OD15 and MF66, respectively. SPIONs produce a decrease in blood pressure and a natriuresis; however, the rate of fluid filtration in the kidney was not significantly affected