Citations: 1-3:
<1>
Authors
Frassetto L. Morris RC Jr. Sebastian A.
Institution
Department of Medicine, University of California, San Francisco 94143, USA.
Title
Potassium bicarbonate reduces urinary
nitrogen excretion in postmenopausal women.
Source
Journal of Clinical Endocrinology & Metabolism. 82(1):254-9, 1997 Jan.
Abstract
Previously we demonstrated that low grade chronic metabolic acidosis exists
normally in humans eating ordinary diets that yield normal net rates of
endogenous acid production (EAP), and that the degree of acidosis increases
with age. We hypothesize that such diet-dependent and age-amplifying low
grade metabolic acidosis contributes to the decline in skeletal muscle mass
that occurs normally with aging. This hypothesis is based on the reported
finding that chronic metabolic acidosis induces muscle protein breakdown, and
that correction of acidosis reverses the effect. Accordingly, in 14 healthy
postmenopausal women residing in a General Clinical Research Center and
eating a constant diet yielding a normal EAP rate, we tested whether
correcting their "physiological" acidosis with orally administered
potassium bicarbonate (KHCO3; 60-120
mmol/day for 18 days) reduces their urinary nitrogen loss. KHCO3 reduced EAP
to nearly zero, significantly reduced the blood hydrogen ion concentration (P
< 0.001), and increased the plasma bicarbonate concentration
(P < 0.001), indicating that pre-KHCO3, diet-dependent EAP was significantly
perturbing systemic acid-base equilibrium, causing a low grade metabolic
acidosis. Urinary ammonia nitrogen, urea nitrogen, and total nitrogen levels
significantly decreased. The cumulative reduction in nitrogen excretion was
14.1 +/- 12.3 g (P < 0.001). Renal creatinine clearance and urine volume
remained unchanged. We conclude that in postmenopausal women, neutralization
of diet-induced EAP with KHCO3 corrects their preexisting diet-dependent low
grade metabolic acidosis and significantly reduces their urinary nitrogen
wasting. The magnitude of the KHCO3-induced nitrogen-sparing effect is
potentially sufficient to both prevent continuing age-related loss of muscle
mass and restore previously accrued deficits.
<2>
Authors
Sebastian A. Harris ST. Ottaway JH. Todd KM. Morris RC Jr.
Institution
Department of Medicine, Moffitt-Long Hospitals, University of California, San
Francisco 94143.
Title
Improved mineral balance and skeletal metabolism in postmenopausal women
treated with potassium bicarbonate [see
comments].
Comments
Comment in: N Engl J Med 1994 Jun 23;330(25):1821-2, Comment in: N Engl J Med
1994 Jul 28;331(4):279, Comment in: N Engl J Med 1994 Nov 10;331(19):1312-3
Source
New England Journal of Medicine. 330(25):1776-81, 1994 Jun 23.
Abstract
BACKGROUND. In normal subjects, a low level of metabolic acidosis and
positive acid balance (the production of more acid than is excreted) are
typically present and correlate in degree with the amount of endogenous acid
produced by the metabolism of foods in ordinary diets abundant in protein.
Over a lifetime, the counteraction of retained endogenous acid by base
mobilized from the skeleton may contribute to the decrease in bone mass that
occurs normally with aging. METHODS. To test that possibility, we
administered potassium bicarbonate to 18
postmenopausal women who were given a constant diet (652 mg [16 mmol] of
calcium and 96 g of protein per 60 kg of body weight). The
potassium bicarbonate was given orally for
18 days in doses (60 to 120 mmol per day) that nearly completely neutralized
the endogenous acid. RESULTS. During the administration of
potassium bicarbonate, the calcium and
phosphorus balance became less negative or more positive--that is, less was
excreted in comparison with the amount ingested (mean [+/- SD] change in
calcium balance, +56 +/- 76 mg [1.4 +/- 1.9 mmol] per day per 60 kg; P =
0.009; change in phosphorus balance, +47 +/- 64 mg [1.5 +/- 2.1 mmol] per day
per 60 kg; P = 0.007) because of reductions in urinary calcium and phosphorus
excretion. The changes in calcium and phosphorus balance were positively
correlated (P < 0.001). Serum osteocalcin concentrations increased from 5.5
+/- 2.8 to 6.1 +/- 2.8 ng per milliliter (P < 0.001), and urinary
hydroxyproline excretion decreased from 28.9 +/- 12.3 to 26.7 +/- 10.8 mg per
day (220 +/- 94 to 204 +/- 82 mumol per day; P = 0.05). Net renal acid
excretion decreased from 70.9 +/- 10.1 to 12.8 +/- 21.8 mmol per day,
indicating nearly complete neutralization of endogenous acid. CONCLUSIONS. In
postmenopausal women, the oral administration of potassium
bicarbonate at a dose sufficient to neutralize endogenous
acid improves calcium and phosphorus balance, reduces bone resorption, and
increases the rate of bone formation.
<3>
Authors
Sudhir K. Kurtz TW. Yock PG. Connolly AJ. Morris RC Jr.
Institution
Department of Medicine, University of California, San Francisco 94143-0126.
Title
Potassium preserves endothelial function and enhances aortic
compliance in Dahl rats.
Source
Hypertension. 22(3):315-22, 1993 Sep.
Abstract
It has recently been proposed that in rat models of genetic hypertension,
supplemental dietary potassium preserves release of
endothelium-derived relaxing factor independently of its capacity to either
attenuate hypertension or increase plasma potassium. To test
this hypothesis in Dahl salt-sensitive rats given sodium chloride (4%) for 3
weeks, we supplemented dietary potassium (2.1%) with either
KCl (n = 16) or KHCO3 (n = 16). Compared with unsupplemented rats (n = 16),
rats supplemented with either potassium salt had a lower
mean arterial pressure and a greater release of endothelium-derived relaxing
factor, as assessed from acetylcholine-induced relaxation of precontracted
aortic rings. However, the maximum relaxation response to acetylcholine
correlated inversely with blood pressure (r = -.82, P < .001), not only in
the KCl (r = -.68, P < .002) and KHCO3 (r = -.77, P < .001) groups but also
in unsupplemented rats (r = -.86, P < .001). With potassium
supplementation, plasma potassium concentrations measured
between 4 and 6 PM did not increase, but those measured between 4 and 6 AM
did increase (P < .05). In isolated ring segments, aortic compliance was
greater in both the KCl and KHCO3 groups than in unsupplemented rats (0.015
and 0.017 vs 0.009 mm2/mm Hg) (P < .01). This greater compliance could not be
related to differences in blood pressure, plasma potassium,
or collagen or elastin content of the aortic wall.(ABSTRACT TRUNCATED AT 250
WORDS)