X-Message-Number: 9273
Date: Fri, 13 Mar 1998 04:05:53 -0800 (PST)
From: Doug Skrecky <>
Subject: potassium bicarbonate reduces urinary nitrogen excretion

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.

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