AJP - Endocrinology and Metabolism, Vol 263, Issue 2 E245-E249, Copyright © 1992 by American Physiological Society
Platelet catecholamine contents as related to trait anxiety and aerobic fitness
I. Van Faassen, C. Popp-Snijders, J. J. Nauta, G. van Zijderveld, L. J. van Doornen and F. J. Tilders
Department of Endocrinology, Free University Hospital, Amsterdam, The Netherlands.
Platelet catecholamines (CA) are derived from plasma and are considered as
a cumulative index of sympathoadrenal activity. We investigated whether
trait anxiety (TA) and aerobic fitness, two interrelated long-term
determinants of sympathoadrenal activity, affect platelet CA concentration
as measured in rest and after acute increments of plasma epinephrine (Epi).
For that purpose, platelet CA were measured 15 min before and after Epi
infusion (5-160 ng.kg-1.min-1, increased in 6 steps) in 45 healthy male
students with high (n = 21) and low (n = 24) TA, of whom maximal aerobic
power (VO2max) was assessed. Plasma CA and electrolytes were measured
during each infusion rate. Epi infusion significantly raised platelet Epi
by 67% and decreased platelet and plasma norepinephrine (NE) by 23 and 17%.
Plasma potassium significantly decreased by 32% and plasma sodium slightly
increased. Platelet Epi increase was inversely related to basal platelet
Epi (r = -0.58, P less than 0.001). Platelet NE decrease was positively
associated with basal platelet NE and plasma potassium levels (r = 0.50, P
less than 0.01). TA and VO2max were not related to basal levels and
responses of electrolytes and platelet NE. VO2max was correlated with
platelet Epi increase in low TA (r = 0.62, P = 0.002), whereas no such
relationship existed in high TA (r = 0.008). We conclude that fitness
positively influences platelet Epi accumulation, but that high TA
interferes with this relationship.
