Chronic renal failure alters endothelial function in cerebral circulation in mice.

We examined structure, composition, and endothelial function in cerebral arterioles after 4 wk of chronic renal failure (CRF) in a well-defined murine model (C57BL/6J and apolipoprotein E knockout female mice). We also determined quantitative expression of endothelial nitric oxide synthase (eNOS), phosphorylated eNOS (on serine 1177 and threonine 495), and caveolin-1; quantitative expression of markers of vascular inflammation or oxidative stress [Rock-1, Rock-2, VCAM-1, and peroxisome proliferator-activated receptor-γ (PPARγ)]; and the plasma concentration of L-arginine and asymmetric dimethylarginine (ADMA). Our hypothesis was that endothelial function would be impaired in cerebral arterioles during CRF following either a decrease in NO production (through alteration of eNOS expression or regulation) or an increase in NO degradation (due to oxidative stress or vascular inflammation). Endothelium-dependent relaxation was impaired during CRF, but endothelium-independent relaxation was not. CRF had no effect on cerebral arteriolar structure and composition. Quantitative expressions of eNOS, eNOS phosphorylated on serine 1177, caveolin-1, Rock-1, Rock-2, and VCAM-1 were similar in CRF and non-CRF mice. In contrast, quantitative expression of PPARγ (which exercises a protective role on blood vessels) was significantly lower in CRF mice, whereas quantitative expression of eNOS phosphorylated on the threonine 495 (the inactive form of eNOS) was significantly higher. Lastly, the plasma concentration of ADMA (a uremic toxin and an endogenous inhibitor of eNOS) was elevated and plasma concentration of L-arginine was low in CRF. In conclusion, endothelial function is impaired in a mouse model of early stage CRF. These alterations may be related (at least in part) to a decrease in NO production.

Cerebral arterioles preparation and PECAM-1 expression in C57BL/6J and ApoE-/- mice.

Exploration of molecular mechanisms involved in alterations of cerebral blood vessels in pathology such as chronic kidney disease implies cerebral vessel isolation for proteins and mRNAs quantification. We describe an updated method to isolate brain microvessels from wild type (WT) mice at 14 weeks of age. The quality of cerebral arterioles preparation was determined by measuring the enzymatic activity of gamma-glutamyl transpeptidase, an enzyme that is especially expressed in cerebral microvessels, and the quantitative expression (Western Blot) of platelet endothelial cell adhesion molecule-1 (PECAM-1), alpha-actin and gamma-enolase as markers of respectively endothelial cells, smooth muscle cells and neurons. We then assessed PECAM-1 expression in 14 and 20 weeks old ApoE(-/-) and WT mice. PECAM-1 expression was increased in 14 weeks old ApoE(-/-) mice compared to age matched WT mice. This difference in PECAM-1 expression disappeared at 20 weeks of age. These findings indicate that the present method of mice cerebral arterioles isolation is a valid method. Moreover, PECAM-1 expression, a marker of endothelial cells, changes with age in cerebral arterioles of ApoE(-/-) mice.