Plasma lactate levels during baseline and blood pressure conditioning in the baboon

Lactic acid in arterial blood, systolic and diastolic blood pressures, and heart rates of baboons were examined for three naive subjects, and for five experimental subjects during baseline conditions and during training to elevate diastolic blood pressure through operant conditioning methodology. Lactic acid and cardiovascular levels were determined at rest (9 a.m.), and at 12:30 and 3:00 p.m. (during conditioning sessions, for trained subjects). At rest (baseline) lactic acid levels and cardiovascular measures were similar for conditioned and naive subjects. During conditioning sessions, blood pressures but not heart rates were significantly elevated. Plasma lactate increased from morning to afternoon in both naive and trained subjects, but at three hours of conditioning, trained subjects had significantly higher lactate levels than when at rest and when compared to naive subjects at the same time of day. This study provides normative data for plasma lactate in the laboratory baboon and also indicates metabolic changes (which may be related to increased muscular work) as part of concurrent changes in multiple systems (e.g., neural, hormonal) which accompany conditioned blood pressure elevations.