BODY-FLUID HOMEOSTASIS AND CARDIOVASCULAR ADJUSTMENTS DURING SUBMAXIMAL EXERCISE - INFLUENCE OF CHEWING COCA LEAVES

The present study was undertaken to determine the haematological and c ardiovascular status, at rest and during prolonged (1 h) submaximal ex ercise (approximately 70% of peak oxygen uptake) in a group (n = 12) o f chronic coca users after chewing approximately 50 g of coca leaves. The results were compared to those obtained in a group (n = 12) of non chewers. At rest, coca chewing was accompanied by a significant increa se in heart rate [from 60 (SEM 4) TO 76 (SEM 3) beats.min(-1)], in hae matocrit [from 53.2 (SEM 1.2) to 55.6 (SEM 1.1)%] in haemoglobin conce ntration, and plasma noradrenaline concentration [from 2.8 (SEM 0.4) t o 5.0 (SEM 0.5) mu mol.l(-1)]. It was calculated that coca chewing for 1 h resulted in a significant decrease in blood [-4.3 (SEM 2.2)%] and plasma [-8.7 (SEM 1.2)%] volume. During submaximal exercise, coca che wers displayed a significantly higher heart rate and mean arterial blo od pressure. The exercise-induced haemoconcentration was blunted in co ca chewers compared to nonchewers. It was concluded that the coca-indu ced fluid shift observed at rest in these coca chewers was not cumulat ive with that of exercise, and that the hypovolaemia induced by coca c hewing at rest compromised circulatory adjustments during exercise.