Effect of a diet rich in fat and/or fructose on potassium channel gene expression in rat small mesenteric artery

We tested if arterial K + channel gene expression is reduced under dietary conditions mimicking the metabolic syndrome. Male Sprague‐Dawley rats were fed high‐fat + high‐fructose (HFF; N=4) or high‐fructose (HF; N=4) diet from 4 to 32 weeks (wks) of age. Age‐matched control rats (CTRL) were fed normal chow (N=4 in each group). Systolic blood pressure (SBP) was measured using the tail cuff method. mRNA expression of K + channels in mesenteric arteries was measured using quantitative real‐time polymerase chain reaction (Q‐PCR). At 32 wks body weight (BW) was increased in HFF (639±37g; P<0.05) compared to CTRL (522±22g), whereas BW was similar in HF (574±35g) and CTRL (564±15g). Average SBP through wks 10–32 was higher in both HFF and HF rats compared to their respective CTRL (HFF: 134±4 mmHg vs. 121±2 mmHg, P<0.05; and HF: 131±5 mmHg vs. 118±2 mmHg, P<0.05). In small mesenteric artery of HFF rats, mRNA expression of SK3 was reduced to 59% of that in CTRL (P<0.05) and K V 1.5 was reduced to 73% of that in CTRL (P<0.01), while Kir2.1, Kir6.1, BK Ca , IK Ca , K V 1.2 and K V 7.4 expression was unchanged. HF diet did not significantly change K + channel expression. We conclude that reduced expression of SK3 and K V 1.5 channels might partially explain the increased SBP in metabolically challenged rats fed a diet rich in fructose + fat but not in those fed high‐fructose only. Grants: Danish National Research Foundation (F.); Danish Heart F.; Lundbeck F.