Fluid regulatory hormone response to exercise after coca-induced body fluid shifts
Fecha
1997Autor
Favier, R
Cáceres, E
Sempore, B
Cottet-Emard, JM
Gauquelin, G
Gharib, C
Spielvogel, H
Metadatos
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To determine the effect of coca chewing on heart rate
(HR), mean arterial blood pressure (MAP), and plasma
volume and their relationship with the hormones regulating
cardiovascular and body fluid homeostasis, 16 male volunteers were examined at rest and during 1 h of cycle exercise at
,75% of their peak oxygen uptake in two trials separated by
1 mo. One trial was performed after the subjects chewed a
sugar-free chewing gum (Coca2 trial), whereas the other was
done after the subjects chewed 15 g of coca leaves (Coca1),
with the order of the Coca2 and Coca1 trials being randomized. Blood samples were taken at rest, before (R1) and after
1-h chewing (R2), and during the 5th, 15th, 30th, and 60th
min of exercise. They were analyzed for hematocrit, hemoglobin concentration, red blood cell count, plasma proteins, and
for the fluid regulatory hormones, including plasma catecholamines [norepinephrine (NE) and epinephrine], renin, arginine vasopressin, and the atrial natriuretic peptide (ANP).
During the control trial (Coca2), from R1 to R2, there was no
significant change in hematologic, hormonal, and cardiovascular status except for a small increase in plasma NE. In
contrast, it can be calculated that coca chewing at rest
induced a significant hemoconcentration (23.8 6 1.3% in
blood and 27.0 6 0.7% in plasma volume), increased NE and
MAP, and reduced plasma ANP. Chewing coca before exercise
reduced the body fluid shifts but enhanced HR response
during exercise. These effects were not accompanied by
changes in NE, epinephrine, renin, and arginine vasopressin
plasma levels. In contrast, plasma ANP response to exercise
was lower during the Coca1 trial, suggesting that central
cardiac filling was reduced by coca use. It is likely that the
reduction in body fluid volumes is a major contributing factor
to the higher HR at any given time of exercise after coca
chewing.