Obesity associated hypertension in rodent models is commonly associated with altered vascular reactivity to sympathetic neurotransmitters and inflammation-induced vascular remodeling/fibrosis. Dahl salt-sensitive (SS) rats exhibit elevated sympathetic activity and vascular remodeling. We hypothesized that diet-induced obesity in Dahl SS rats would promote hypertension, vascular dysfunction and remodeling/fibrosis. Male Dahl SS rats were placed on high fat diet (HFD, 60% kcal from fat with final concentrations of 0.33% NaCl and 1% K
+
, n=5) or normal-fat diet (NFD; 10% kcal from fat, 0.24% NaCl, 0.36% K
+
, n=5) for 24-26 weeks after weaning (3 weeks of age). Compared with NFD rats, HFD rats displayed severe hypertension (MAP, 165±4 mmHg vs 133±6 mmHg, P<0.05), higher body-weight (470±6g vs 433±7g, P<0.05), and hyperlipidemia (cholesterol, 211±22 mg/dl vs 138±23 mg/dl, P=0.05). HFD rats did not show significant changes in plasma levels of fasting glucose (85±5 mg/dl vs 75±5 mg/dl), insulin (2.6±0.8 ng/ml vs 2.2±1.1 ng/ml), leptin (0.77±0.18 ng/ml vs 0.44±0.06 ng/ml), or aldosterone (249±3 pg/ml vs 234±3 pg/ml) (all P>0.05). HFD did not affect pressurized mesenteric arterial (~300 μm inner diameter, 60 mmHg) reactivity to norepinephrine or ATP
in vitro
. Pressurized mesenteric arteries from HFD rats displayed thicker walls (Ca
2+
free buffer, 40±1 μm vs 36±1 μm, P<0.05), but showed slightly increased distensibility. Morphological studies did not reveal greater fibrosis in adventitia of mesenteric, intrarenal and coronary arteries from HFD rats. However, HFD induced inflammation in mesenteric perivascular adipose tissue, as shown by increased CD3 positive cell infiltration and histological evidence of fibrosis and angiogenesis. Our studies indicate that HFD in male Dahl SS rats promotes hypertension, perivascular adipose tissue inflammation and vascular remodeling, but not vascular fibrosis. Alteration of vascular contractility to sympathetic neurotransmitters, however, is not required for obesity associated hypertension in Dahl SS rats.
Long Term High-Fat Diet-Induced Modification of Vascular Wall and Perivascular Adipose Tissue-Mediated Oxidative Stress: Consequences for Endothelium-Independent Vascular Function in Rats