The effect of dietary potassium and chloride on cation-anion balance in swine.
The apparent retention and excretion of cations and anions were evaluated in 20 growing pigs to study the mechanisms by which an interaction between dietary K and Cl levels affected growth. All pigs maintained a positive retention of K+ and Cl- regardless of the dietary levels. The K x Cl interaction observed in growth studies previously but not in this study could not be explained by a simple interaction of one ion on the retention of the other. When pooled across dietary Cl levels, an increase in dietary K levels from .10 to .60% resulted in a calculated increase in daily K+ intake of 4.86 meq/kg of BW. Sixty percent (2.99 meq) of the increased K+ intake was excreted in the urine and counterbalanced by a decrease in urine NH4+ (3.06 meq). This decrease in NH4+ excretion could account for essentially all of the increase in N retention (3.51 mmol) observed when dietary K levels were increased from .10 to .60%. Thirty-three percent of the increased K+ intake (1.62 meq) was retained, but the counter ion could not be determined. Retention of Cl- was not changed as dietary K levels were changed. When dietary Cl levels were increased from .03 to .57%, 69% (4.06 meq) of the calculated difference in Cl- intake (5.90 meq) was excreted in the urine, which must have been counterbalanced by a decrease in undetermined organic anions (1.77 meq) and HPO4 = (1.50 meq) excretion, with a tendency for an increased NH4+ (.82 meq) excretion. The counter ions required to balance the increased Cl- retention (1.82 meq) as dietary Cl levels were increased from .03 to .57% could not be identified. Shifts in the retention and urinary excretion of Ca++, Na+, HCO3-, and SO4= did not seem to be quantitatively important in identifying the mechanisms by which dietary K and Cl levels alter growth. Based on these results, we conclude that alterations in growth caused by changes in dietary K and possibly Cl levels are mediated via mechanisms involving renal NH4+ metabolism.
Golz
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DI
University of Wisconsin, Madison 53706.
Crenshaw
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TD
D000641:Ammonia / Q000378:metabolism; D000818:Animals; D000838:Anions; D002118:Calcium / Q000378:metabolism; D002412:Cations; D002712:Chlorides / Q000493:pharmacokinetics / Q000494:pharmacology*; D004032:Diet; D004063:Digestion; D008297:Male; D011188:Potassium / Q000493:pharmacokinetics / Q000494:pharmacology*; D011897:Random Allocation; D013552:Swine / Q000378:metabolism*; D014554:Urination / Q000187:drug effects; D014882:Water-Electrolyte Balance / Q000187:drug effects*
D000838:Anions; D002412:Cations; D002712:Chlorides; D000641:Ammonia; D011188:Potassium; D002118:Calcium