J Korean Med Sci.  2010 Jan;25(1):16-23. 10.3346/jkms.2010.25.1.16.

HMG-CoA Reductase Inhibitor Improves Endothelial Dysfunction in Spontaneous Hypertensive Rats Via Down-regulation of Caveolin-1 and Activation of Endothelial Nitric Oxide Synthase

• Suh JW
• Choi DJ
• Chang HJ
• Cho YS
• Youn TJ
• Chae IH
• Kim KI
• Kim CH
• Kim HS
• Oh BH
• Park YB

• KMID: 1713826
• DOI: http://doi.org/10.3346/jkms.2010.25.1.16

Abstract

Hypertension is associated with endothelial dysfunction and increased cardiovascular risk. Caveolin-1 regulates nitric oxide (NO) signaling by modulating endothelial nitric oxide synthase (eNOS). The purpose of this study was to examine whether HMG-CoA reductase inhibitor improves impaired endothelial function of the aorta in spontaneous hypertensive rat (SHR) and to determine the underlying mechanisms involved. Eight-week-old male SHR were assigned to either a control group (CON, n=11) or a rosuvastatin group (ROS, n=12), rosuvastatin (10 mg/kg/day) administered for eight weeks. Abdominal aortic rings were prepared and responses to acetylcholine (10-9-10-4 M) were determined in vitro. To evaluate the potential role of NO and caveolin-1, we examined the plasma activity of NOx, eNOS, phosphorylated-eNOS and expression of caveolin-1. The relaxation in response to acetylcholine was significantly enhanced in ROS compared to CON. Expression of eNOS RNA was unchanged, whereas NOx level and phosphorylated-eNOS at serine-1177 was increased accompanied with depressed level of caveolin-1 in ROS. We conclude that 3-Hydroxy-3-methylglutaryl Coenzyme-A (HMG-CoA) reductase inhibitor can improve impaired endothelial dysfunction in SHR, and its underlying mechanisms are associated with increased NO production. Furthermore, HMG-CoA reductase inhibitor can activate the eNOS by phosphorylation related to decreased caveolin-1 abundance. These results imply the therapeutic strategies for the high blood pressure-associated endothelial dysfunction through modifying caveolin status.

Keyword

Hydroxymethylglutaryl-CoA Reductase Inhibitors; Caveolins; Nitric Oxide; Nitric Oxide Synthase Type III

MeSH Terms

Acetylcholine/metabolism
Animals
Aorta/metabolism/physiopathology
Blood Pressure/drug effects
Caveolin 1/*metabolism
Down-Regulation
Drug Administration Schedule
Endothelium, Vascular/*drug effects/physiopathology
Fluorobenzenes/administration & dosage/*pharmacology
Hydroxymethylglutaryl-CoA Reductase Inhibitors/administration & dosage/*pharmacology
Hypertension/enzymology/metabolism/*physiopathology
Male
Nitric Oxide/blood
Nitric Oxide Synthase Type III/*metabolism
Phosphorylation
Pyrimidines/administration & dosage/*pharmacology
Rats
Rats, Inbred SHR
Sulfonamides/administration & dosage/*pharmacology
Vasodilation/drug effects
Caveolin 1
Fluorobenzenes
Hydroxymethylglutaryl-CoA Reductase Inhibitors
Pyrimidines
Sulfonamides
Nitric Oxide
Acetylcholine
Nitric Oxide Synthase Type III

Figure

• 

  Fig. 1 Treatment of rosuvastatin (10 mg/kg/day) for 8 weeks significantly enhances endothelium-dependent vasodilatation in the aorta of SHRs. (A) Aortic rings from rosuvastatin-treated SHRs exhibit a significantly higher response to acetylcholine-induced vasorelaxation compared with control SHRs (n=8 for each group). (B) Addition of NO analog, sodium nitroprusside, to the medium induced complete vasorelaxation, indicating maintenance of proper smooth muscle cell function in SHRs. Column=mean values, error bar=standard error. *P<0.05 as compared to the control.

• 

  Fig. 2 Plasma nitrite and nitrate concentration is increased in rosuvastatin-treated group. NOx concentration in plasma, representing the circulating pool of bioactive nitrate and nitrite, was approximately 1.6 fold higher in rosuvastatin-treated group than control group. Column=mean values, error bar=standard error. *P<0.05 as compared to the control.

• 

  Fig. 3 (A) eNOS mRNA expression in aorta from rosuvastatin-treated or control SHRs. mRNA expression of eNOS was not different between two groups. (B) Protein expression of eNOS was also not different between two groups. However, phosphorylated eNOS (p-eNOS) was expressed much higher (≈2.3 fold) in rosuvastatin-treated compared with control SHRs. The expression level of p-eNOS was determined by western blot with monoclonal-anti-phospho-eNOS antibody at Ser1177. Column=mean values, error bar=standard error. *P<0.05 as compared to the control.

• 

  Fig. 4 Assessment of the effect of rosuvastatin on caveolin-1 protein in the aorta of rats Top: Immunoblot of caveolin-1 protein in the aorta (lane 1, 2, 3, and 4, aorta from control SHR; lane 5, 6, 7, and 8, aorta from the rosuvastatin-treated SHR). Bottom: quantified data for caveolin-1 protein in rosuvastatin-treated and control SHRs. Optical density caveolin-1 positive bands were quantified by scanning densitometry and plotted relative to the control. Column=mean values, error bar=standard error. *P<0.01 as compared to the control.

• 

  Fig. 5 Down-regulation of caveolin-1 by treatment of rosuvastatin in aortic endothelium of SHRs. The expression of caveolin-1 in aortic endothelium of control SHR (A), and rosuvastatin-treated SHR (B). The level of expression of caveolin-1 was determined by immunohistochemical staining with polyclonal-anti-caveolin-1 antibody. Endothelial cells of the aorta were stained and the arrow indicates caveolin-1.

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