HISTAMINE AND EXERCISE-INDUCED HYPOXEMIA IN HIGHLY TRAINED ATHLETES

To determine whether exercise-induced hypoxemia in extreme athletes re sults from an increase in histamine level during maximal incremental e xercise, seven young athletes [YA; age 22.2 +/- 1.23 (SE) yr] and seve n master athletes (MA; age 66.2 +/- 2.94 yr), all of whom were known t o develop exercise-induced hypoxemia, were compared with age-matched c ontrol groups (young controls and older controls, respectively). Durin g maximal incremental exercise, blood samples for arterial blood gas a nalysis and for plasma and total histamine were drawn at rest and at 5 0, 75, and 100% of maximal O-2 uptake. The percentage of histamine rel eased (%H) was calculated from plasma and total histamine samples. In all athletes (MA and YA groups), exercise induced an increase in %H wi th a concomitant decrease in arterial Po-2 (Pa-o2); in control groups there was no change in either histamine levels or Pa-o2. When the data for the YA and MA groups were combined, a correlation was observed be tween the increase in %H and the drop in Pa-o2. Nevertheless, further studies are required to establish whether histamine plays a causative role in hypoxemia or is a response to injury.