High potassium intake inhibits neointima formation in the rat carotid artery balloon injury model

Recently, we reported that elevated extracellular potassium concentration i n vitro inhibited proliferation and migration of vascular smooth muscle cel ls, formation of free radical compounds by macrophages, and reduced platele t sensitivity to agonists. In the present study we analyzed the effects of long-term, in vivo elevation of extracellular potassium concentration resul ting from changes in dietary potassium intake on the vascular response to i njury. The rat carotid artery balloon injury model was employed in 70 adult Sprague Dawley rats assigned to three groups. Beginning 14 days before sur gical placement of the carotid lesion and continuing until death, the anima ls were fed diets containing either low (0.1% potassium, n = 25), normal (1 .5% potassium, n = 19), or high potassium (4.0% potassium, n = 26). Fourtee n days postsurgery the animals were killed and the arteries were analyzed t o determine quantitatively the ratio of neointimal to medial area. Dietary potassium had a significant effect on arterial plasma potassium concentrati on (one-way analysis of variance, P < .01). Group mean and standard errors were 4.26 +/- 0.12 mmol/L for the low-potassium group, 5.22 +/- 0.19 mmol/L for normal, and 5.80 +/- 0.23 mmol/L for the high-intake group. Increases in dietary potassium attenuated neointima formation significantly (P < .05, one-way analysis of variance), with the mean ratio of neointimal area to m edial area being 0.447 +/- 0.106 for the low-intake animals, 0.384 +/- .116 for normal, and 0.240 +/- .046 for the high-intake group. These results ar e consistent with a hypothesis that a high level of potassium intake is eff ective in inhibiting neointima formation in vivo. Am J Hypertens 2000;13:10 14-1020 (C) 2000 American Journal of Hypertension, Ltd.