Effects of NaHCO3 loading on acid-base balance, lactate concentration, and performance in racing greyhounds.

This investigation examined the effects of NaHCO3 loading on lactate concentration ([La]), acid-base balance, and performance for a 603. 5-m sprint task. Ten greyhounds completed a NaHCO3 (300 mg/kg body weight) and control trial in a crossover design. Results are expressed as means +/- SE. Presprint differences (P < 0.05) were found for NaHCO3 vs. control, respectively, for blood pH (7.47 +/- 0.01 vs. 7.42 +/- 0.01), HCO-3 (28.4 +/- 0.4 vs. 23.5 +/- 0.3 meq/l), and base excess (5.0 +/- 0.3 vs. 0.2 +/- 0.3 meq/l). Peak blood [La] increased (P < 0.05) in NaHCO3 vs. control (20.4 +/- 1.6 vs. 16.9 +/- 1.3 mM, respectively). Relative to control, NaHCO3 produced a greater (P < 0.05) reduction in blood base excess (-18.5 +/- 1.4 vs. -14.1 +/- 0.8 meq/l) and HCO-3 (-17.4 +/- 1.2 vs. -12.8 +/- 0.7 meq/l) from presprint to postexercise. Postexercise peak muscle H+ concentration ([H+]) was higher (P < 0.05) in NaHCO3 vs. control (158.8 +/- 8.8 vs. 137.0 +/- 5.3 nM, respectively). Muscle [H+] recovery half-time (7.2 +/- 1.6 vs. 11.3 +/- 1.6 min) and time to predose values (22.2 +/- 2.4 vs. 32.9 +/- 4.0 min) were reduced (P < 0.05) in NaHCO3 vs. control, respectively. No differences were found in blood [H+] or blood [La] recovery curves or performance times. NaHCO3 increased postexercise blood [La] but did not reduce the muscle or blood acid-base disturbance associated with a 603.5-m sprint or significantly affect performance.

Time course for exercise-induced alterations in insulin action and glucose tolerance in middle-aged people.

The purposes of this study were 1) to investigate glucose tolerance and insulin action immediately after exercise and 2) to determine how long the improved glucose homeostatic mechanisms observed 12-16 h after exercise persist. Nine (seven men, two women) moderately trained middle-aged (51 +/- 3 yr) subjects performed 45 min of exercise at 73 +/- 2% of peak O2 uptake for 5 days, followed by 7 days of inactivity. Oral glucose tolerance tests (OGTT; 75 g) were performed immediately postexercise (IPE; approximately 30 min) after the final exercise bout and 1, 3, 5, and 7 days after exercise. The incremental area under the plasma glucose curve was markedly higher IPE (355 +/- 82 mM.min) compared with those on days 1 (136 +/- 57 mM.min; P < 0.05) and 3 (173 +/- 62 mM.min; P < 0.05). The glucose area was significantly higher on days 5 (213 +/- 80 mM.min) and 7 (225 +/- 84 mM.min) compared with those on days 1 and 3 (P < 0.05). The incremental insulin area IPE (3,729 +/- 1,104 microU.ml-1.min) was 43% higher compared with that on day 1 (2,603 +/- 635 microU.ml-1.min; P < 0.05) and 66% higher compared with that on day 3 (2,240 +/- 517 microU.ml-1.min; P < 0.05). The insulin area increased to 3,616 +/- 617 microU.ml-1.min after 5 days of inactivity (P < 0.05). An additional 48 h of inactivity did not result in any further increase in the plasma insulin response.(ABSTRACT TRUNCATED AT 250 WORDS)

Safety and efficacy of an avirulent live Salmonella choleraesuis vaccine for protection of calves against S dublin infection.

OBJECTIVE: To evaluate the safety and efficacy of avirulent live Salmonella choleraesuis strain 54 (SC54) as a vaccine to protect calves against salmonellosis caused by S dublin. ANIMALS: 40 head of clinically normal 3 to 5-week-old male Holstein calves that were culture negative for Salmonella sp. PROCEDURE: Calves were randomly assigned to 4 test groups of 10 calves each. Group 1 received 8.5 x 10(7) colony-forming units (CFU) of SC54 SC. Groups 2 and 3 received 1.13 x 10(9) CFU of SC54, SC and intranasally, respectively. Group 4 received saline solution as a vaccine control. All calves were challenge exposed orally with 1.74 x 10(9) CFU of virulent S dublin 14 days after vaccination. Clinical signs and Salmonella shedding were monitored for 28 days after vaccination. Calves were necropsied, and organs were cultured for Salmonella sp 14 days after challenge exposure. RESULTS: Calves of groups 2 and 3 had slightly high rectal temperature after vaccination. Salmonella dublin challenge exposure resulted in mild clinical signs of salmonellosis. All vaccinated groups had significantly (P < 0.05) lower rectal temperature, fecal shedding of S dublin, and recovery of S dublin from organs after necropsy. SC54 was not recovered from fecal or blood samples collected after vaccination or from injection site samples or organs collected at necropsy. CONCLUSIONS: SC54 given intranasally or SC to calves was safe and significantly (P < 0.05) reduced clinical signs and bacterial shedding after oral challenge exposure with S dublin. CLINICAL RELEVANCE: SC54 has potential as an effective vaccine to aid in prevention of salmonellosis caused by S dublin in calves.

Effects of a low-dose amino acid supplement on adaptations to cycling training in untrained individuals.

The purpose of this study was to determine if amino acid supplementation influences blood and muscle lactate response to exercise and the time course of the metabolic adaptations to training. Two groups of untrained males (n = 7 each) were given (double-blind) a daily supplement (2.9 g.day-1) containing a mixture of leucine, isoleucine, valine, glutamine, and carnitine (EXP) or 3 g.day-1 of lactose (CON). Following 7 days of supplementation there was no significant change in VO2peak, time to exhaustion (TTX) at 120% VO2peak, or muscle and blood lactate in either EXP or CON. Subjects then initiated 6 weeks of combined aerobic and anaerobic training on a Monark cycle ergometer. It was found that amino acid supplementation had no effect on either blood or muscle lactate accumulation during exercise, while supplementation resulted in a faster adaptation in buffer capacity. Performance during intense exercise was not improved with amino acid supplementation.