Mice with low intakes of dietary potassium developed significantly higher vascular calcification (which results in hardening of the arteries) and aortic stiffness. Both of these conditions are predictors of heart disease and cardiovascular mortality in humans, found researchers from University of Alabama, Birmingham.
The findings, if applicable in humans, suggest that consuming avocados, bananas and tomatoes – all rich in potassium – may help protect against arterial stiffness.
"The findings have important translational potential," said co-author Professor Paul Sanders, "since they demonstrate the benefit of adequate potassium supplementation on prevention of vascular calcification in atherosclerosis-prone mice, and the adverse effect of low potassium intake."
Mechanism
The researchers also gained an understanding of the complex signalling mechanisms that underlie the arterial and aortic stiffening process.
Previous cell studies had indicated that low potassium level in the culture medium significantly increased calcification of vascular smooth muscle cells (VSMC). The low potassium levels resulted in high intracellular calcium content and higher expression of genetic markers characteristic of bone cells.
The higher level of calcium in the cells triggered a complex signalling mechanism promoting autophagy (the intracellular degradation system) which in turn resulted in calcification.
These effects suggest the transformation of VSMC into cells that possessed bone-like characteristics.
Higher levels of potassium prevented activation of the signalling mechanism and autophagy, thus avoiding the transformation of VSMC.
The atherosclerosis-prone mice were either fed low (0.3% by weight), normal (0.7%) or high (2.1%) potassium diets for 30 weeks.
The researchers found that only relatively small changes in serum potassium levels were capable of regulating the calcification effects.
“Importantly, the increase in vascular calcification and stiffness caused by the reduced-potassium diet occurred with only a small reduction in mean serum potassium concentration, compared with the standard potassium–content diet (3.70 versus 4.27 milliequivalents/ litre (mEq/l).
“Similarly, increased potassium diets resulted in a small increase in serum potassium concentration (4.73 mEq/l) and was sufficient to reduce vascular calcification in atherosclerosis,” they wrote.
“These studies established a potentially novel causative role of dietary potassium intake in regulating atherosclerotic vascular calcification and stiffness, and uncovered mechanisms that offer opportunities to develop therapeutic strategies to control vascular disease,” they concluded.
Source: JCI Insight
Volume 2, issue 19 e94920. DOI: 10.1172/jci.insight.94920
“Dietary potassium regulates vascular calcification and arterial stiffness”
Authors: Yong Sun, Paul W. Sanders, Yabing Chen et al.