X-Message-Number: 26303
Date: Tue, 7 Jun 2005 19:05:39 -0700 (PDT)
From: Doug Skrecky <>
Subject: sodium restriction may accelerate aging

[Increasing potassium might be safer.]

Metabolism. 2003 Aug;52(8):1072-7.
Dietary sodium restriction exacerbates age-related changes in
rat adipose tissue and liver lipogenesis.
  To investigate the effects of prolonged dietary sodium
restriction on lipid metabolism, male rats weighing 35 to 40 g
(just weaned) were fed either a low-salt (LSD) or a normal salt
diet (NSD) and used in metabolic experiments after 1, 2, or 3
months of diet consumption. After 2 and 3 months on the diet,
LSD rats showed increased amounts of lipid in carcass and
retroperitoneal tissue. In both LSD and NSD, extending the
feeding period from 2 to 3 months resulted in a marked reduction
in the in vivo rates of adipose tissue fatty acid synthesis that
was accompanied by increases in liver lipogenesis and in the
activity of adipose tissue lipoprotein lipase (LPL). However,
these increases were more marked in LSD rats. Thus, in vivo
rates of liver fatty synthesis and LPL activity in LSD rats,
which were already higher (by about 35% and 20%, respectively)
than in controls after 2 months, attained levels 50% higher
than those in NSD animals after another month on the diet. Brown
adipose tissue (BAT) thermogenic capacity, estimated after 2
and 3 months by the tissue temperature response to
norepinephrine (NE) injection and by guanosine diphosphate
(GDP) binding to BAT mitochondria, did not change in controls,
but was significantly reduced in LSD rats. This raises the
possibility that a decrease in overall energy expenditure,
together with an LPL-induced increased uptake of preformed
fatty acids from the circulation, may account for the excessive
lipid accumulation in LSD rats. Taken together, the data
indicate that prolonged dietary sodium restriction exacerbates
normal, age-related changes in white and BAT metabolism.

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