title: Acute anemia increases lactate production and decreases clearance during exercise.
abstract: We evaluated whether elevated blood lactate concentration during exercise in anemia is the result of elevated production or reduced clearance. Female Sprague-Dawley rats were made acutely anemic by exchange transfusion of plasma for whole blood. Hemoglobin and hematocrit were reduced 33%, to 8.6 +/- 0.4 mg/dl and 26.5 +/- 1.1%, respectively. Blood lactate kinetics were studied by primed continuous infusion of [U-14C]lactate. Blood flow distribution during rest and exercise was determined from injection of 153Gd- and 113Sn-labeled microspheres. Resting blood glucose (5.1 +/- 0.2 mM) and lactate (1.9 +/- 0.02 mM) concentrations were not different in anemic animals. However, during exercise blood glucose was lower in anemic animals (4.0 +/- 0.2 vs. 4.6 +/- 0.1 mM) and lactate was higher (6.1 +/- 0.4 vs. 2.3 +/- 0.5 mM). Blood lactate disposal rates (turnover measured with recyclable tracer, Ri) were not different at rest and averaged 136 +/- 5.8 mumol.kg-1.min-1. Ri was significantly elevated in both control (260.9 +/- 7.1 mumol.kg-1.min-1) and anemic animals (372.6 +/- 8.6) during exercise. Metabolic clearance rate (MCR = Ri/[lactate]) did not differ during rest (151 +/- 8.2 ml.kg-1.min-1); MCR was reduced more by exercise in anemic animals (64.3 +/- 3.8) than in controls (129.2 +/- 4.1). Plasma catecholamine levels were not different in resting rats, with pooled mean values of 0.45 +/- 0.1 and 0.48 +/- 0.1 ng/ml for epinephrine (E) and norepinephrine (NE), respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Physical Education, University of California, Berkeley.
authors.forename: S G
authors.initials: SG
authors.lastname: Gregg
authors.forename: R S
authors.initials: RS
authors.lastname: Mazzeo
authors.forename: T F
authors.initials: TF
authors.lastname: Budinger
authors.forename: G A
authors.initials: GA
authors.lastname: Brooks
mesh_terms: D000740:Anemia / Q000378:metabolism*; D000818:Animals; D001783:Blood Flow Velocity; D001786:Blood Glucose / Q000032:analysis; D002395:Catecholamines / Q000097:blood; D002851:Chromatography, High Pressure Liquid; D005260:Female; D006400:Hematocrit; D006454:Hemoglobins / Q000032:analysis; D007328:Insulin / Q000097:blood; D007773:Lactates / Q000097:blood / Q000378:metabolism*; D010101:Oxygen Consumption; D010805:Physical Conditioning, Animal; D005082:Physical Exertion; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors
chemical_list: D001786:Blood Glucose; D002395:Catecholamines; D006454:Hemoglobins; D007328:Insulin; D007773:Lactates