Abstract
BackgroundDietary potassium supplementation in hypertensive rats is cardioprotective. This protection includes a blood pressure independent reduction in the amount of damage caused by cerebral ischemia. Therefore, we hypothesized that dietary potassium supplementation would improve the outcome of ischemic stroke by improving cerebral vessel structure in normotensive rats.MethodsWistar Kyoto (WKY) rats were fed a high (HK) or low potassium (LK) diet for six weeks from six weeks of age. At the end of treatment, cerebral ischemia was induced by middle cerebral artery (MCA) occlusion and the resultant infarct was quantified and expressed as a percentage of the hemisphere infarcted (%HI). MCA structure was assessed in an additional group of rats using a pressurized arteriograph.ResultsThe cerebral infarct was significantly smaller in rats fed the HK diet, compared to rats fed the LK diet (21 ± 5.4 vs 33.5 ± 4.8 %HI HK vs LK p < 0.05). Vessel structure was improved in WKY rats fed the HK diet as indicated by an increase in the MCA lumen (298 ± 6.3 vs 276 ± 3.9 μm HK vs LK p < 0.05) and outer diameters (322 ± 7.6 vs 305 ± 4.8 μm HK vs LK p < 0.05). Wall thickness and area were unchanged, suggesting an outward euthrophic remodelling process. The HK diet had no effect on body weight or telemetry blood pressure.ConclusionThese studies are the first to show a beneficial effect of dietary potassium in rats with normal blood pressure.
Highlights
Dietary potassium supplementation in hypertensive rats is cardioprotective
Plasma electrolytes and body weights Dietary potassium supplementation had no effect on the mean arterial blood pressure in the Wistar Kyoto (WKY) rats (Figure 1)
The plasma sodium levels were similar between the two groups (142 ± 1.8 vs 144 ± 1.7 HK vs LK), there was a trend toward an increase in the plasma potassium levels in the rats fed the HK diet (5.2 ± 0.2 vs 4.9 ± 0.2 HK vs LK p = 0.25)
Summary
Dietary potassium supplementation in hypertensive rats is cardioprotective. This protection includes a blood pressure independent reduction in the amount of damage caused by cerebral ischemia. Epidemiological studies show that potassium intake correlates inversely with the incidence of cerebrovascular events [1,2,3,4] It has been clear for some time that a high potassium diet reduces the number of hemorrhagic strokes in stroke prone spontaneously hypertensive rats (SHRSP) [5,6] and reduces the risk of stroke in humans [1,2,3]. We have recently shown that dietary potassium supplementation reduces the size of ischemic cerebral infarcts in SHRSP and improves the structure of the MCA [8]. Dietary potassium supplementation did not alter blood pressure in the SHRSP fed a normal sodium diet. This presents the possibility that the effects of potassium supplementation are blood pressure independent and may occur in normotensive rats
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