potassium's cardioprotective mechanisms
Doug Skrecky (oberon@vcn.bc.ca)
Sat, 23 May 1998 05:12:52 -0700 (PDT)
Authors
Young DB. Lin H. McCabe RD.
Institution
Department of Physiology and Biophysics, University of Mississippi Medical
Center, Jackson 39216-4505, USA.
Title
Potassium's cardiovascular protective mechanisms. [Review]
[88 refs]
Source
American Journal of Physiology. 268(4 Pt 2):R825-37, 1995 Apr.
Abstract
High rates of potassium intake are associated with
protection from cardiovascular diseases in populations consuming primitive
diets and in vegetarians living in industrialized cultures. In studies in
humans and in animals, a strong inverse association between
potassium intake and hypertension and stroke has been
described. However, acceptance of the putative protective effect has been
limited by inadequate understanding of 1) long-term
potassium regulation, and 2) mechanisms by which small
changes in plasma potassium concentration may affect
development of cardiovascular diseases. In this review, we present results
from analyses of long-term potassium regulation that
indicated 1) changes in potassium intake may result in
potassium concentrations from 3.1 to 4.6 mmol/l, and 2) when
the initial rate is below normal, potassium concentration is
very sensitive to changes in potassium intake rate. In
addition, we present results that provide bases for possible mechanisms by
which potassium may protect against cardiovascular diseases:
1) increases in potassium inhibit free radical formation
from vascular endothelial cells and macrophages; 2) elevation of
potassium inhibits proliferation of vascular smooth muscle
cells; 3) platelet aggregation and arterial thrombosis are inhibited by
elevation of potassium; and 4) renal vascular resistance is
reduced and glomerular filtration rate is increased by elevation of plasma
potassium. We propose that elevation of dietary
potassium intake increases plasma potassium
concentration, thereby inhibiting free radical formation, smooth muscle
proliferation, and thrombus formation. As a result, the rate of
atherosclerotic lesion formation and thrombosis will be diminished. In
addition, we propose the increase in glomerular filtration rate will cause a
shift in the relationship between arterial pressure and sodium excretion that
will lead to a reduction in arterial blood pressure. By these actions, high
levels of dietary intake of potassium could provide the
observed protection against the cardiovascular diseases that have plagued
humankind since we began eating a modern high-sodium,
low-potassium diet. [References: 88]