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1 Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri, United States
2 Department of Nutritional Sciences, University of Missouri-Columbia, Columbia, United States
3 Department of Biomedical Science, University of Missouri, Columbia, Missouri, United States
* To whom correspondence should be addressed. E-mail: rubinl{at}missouri.edu.
Potassium channels in vascular smooth muscle (VSM) control vasodilation and are potential regulatory targets. This study evaluated effects of gender, exercise training (EX), and high fat diet (HF) on potassium currents (IK) of coronary VSM cells. Yucatan male and female swine were assigned to either sedentary confinement (SED), 16 weeks of EX, 20 weeks of HF, or 20 weeks HF with 16 weeks EX (HF-EX). VSM cells of normal diet SED exhibited three components of IK: 4-AP sensitive IK(KV), TEA sensitive IK(BK), and 4-AP/TEA insensitive IK. Females exhibited significantly higher basal IK than males in the same group. EX increased basal IK in males and females. HF reduced IK in males and females and nullified effects of EX. Endothelin-1 (ET-1) increased IK significantly in males but not females. In the presence of ET-1: 1) IK(KV) was similar in SED males and females and EX increased IK(KV) to a greater extent in males than females. 2) IK(BK) was greater in SED females than males and EX increased IK(BK) to a greater extent in males resulting in IK(BK) similar to EX females. Importantly, HF nullified effects of EX on IK(KV) and IK(BK). These data indicate that basal IK of SED female swine is inherently greater than SED males and that males require EX to achieve comparable levels of IK. Importantly, HF reduced IK in males and females and nullified effects of EX suggesting a high fat diet abrogates beneficial effects of EX on coronary smooth muscle.
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