title: Effects of chronic metabolic acidosis on splanchnic protein turnover and oxygen consumption in human beings.
abstract: OBJECTIVE
  Although metabolic acidosis stimulates protein catabolism, its effects on splanchnic protein turnover and energy expenditure have not been measured in human beings. We investigated the effects of chronic metabolic acidosis (CMA) on splanchnic protein dynamics and oxygen consumption in human beings by using a leucine tracer and mass-balance techniques.
  
  
  METHODS
  Five subjects were studied after 6 days of HCl-, CaCl(2)-, and NH(4)Cl-induced acidosis; 8 subjects served as controls. Blood samples were collected from the radial artery and the hepatic veins. Measurements were performed on plasma and whole-blood samples.
  
  
  RESULTS
  Based on plasma measurements, subjects who had undergone CMA had lower rates of splanchnic proteolysis (-35%) and protein synthesis (-50%; P < .05) than controls, as well as a negative leucine kinetic balance (-6.81 +/- 2.48 micromol/kg/min/1.73 m(2) body surface [BS](-1)), compared with the neutral balance in control plasma samples (0.76 +/- 2.11 micromol/kg/min/1.73; P < .05 between groups). Based on measurements from whole blood, splanchnic proteolysis and protein synthesis did not differ significantly between CMA and control samples, and the net leucine kinetic balance was neutral in both groups (CMA, -0.69 +/- 1.57; controls, -0.74 +/- 3.45 micromol/kg/min/1.73). In CMA whole-blood measurements, splanchnic oxygen consumption (44.8 +/- 4.3 mL/min/1.73 m(2) BS) was slightly lower than in controls (57.5 +/- 8.4 mL/min/1.73 m(2) BS; P = NS). Splanchnic protein synthesis correlated with oxygen consumption (r = 0.82; P < .001).
  
  
  CONCLUSIONS
  CMA reduces splanchnic protein turnover and results in a negative leucine balance--an effect that apparently is offset by the contribution of blood cells to organ leucine (and protein) dynamics. Protein synthesis is a major contributor (about 67%) to energy expenditure in splanchnic organs.
authors.affiliation: Department of Clinical and Experimental Medicine, University of Padova, Padova, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Tessari
authors.forename: Antonella
authors.initials: A
authors.lastname: Sofia
authors.forename: Stefano
authors.initials: S
authors.lastname: Saffioti
authors.forename: Monica
authors.initials: M
authors.lastname: Vettore
authors.forename: Daniela
authors.initials: D
authors.lastname: Verzola
authors.forename: Renato
authors.initials: R
authors.lastname: Millioni
authors.forename: Lucia
authors.initials: L
authors.lastname: Puricelli
authors.forename: Giacomo
authors.initials: G
authors.lastname: Garibotto
mesh_terms: D000138:Acidosis / Q000378:metabolism*; D000328:Adult; D000641:Ammonia / Q000378:metabolism; D002908:Chronic Disease; D005260:Female; D006801:Humans; D007930:Leucine / Q000378:metabolism; D008297:Male; D008643:Mesentery / Q000378:metabolism*; D008875:Middle Aged; D010101:Oxygen Consumption; D011506:Proteins / Q000378:metabolism*
chemical_list: D011506:Proteins; D000641:Ammonia; D007930:Leucine