Secretory immunoglobulin A and cardiovascular reactions to mental arithmetic, cold presser, and exercise: Effects of alpha-adrenergic blockade

The mechanism underlying acute changes in secretory immunoglobulin A (sIgA) remains to be determined. In this experiment sIgA and cardiovascular activ ity were monitored at rest and while participants performed a mental arithm etic task, cold presser, and submaximal cycle exercise following placebo or 1 mg of the alpha-adrenergic blocker, doxazosin. Under placebo, the tasks produced patterns of cardiovascular activity indicative of combined alpha- and beta-adrenergic, alpha-adrenergic, and beta-adrenergic activation, resp ectively. Doxazosin was associated with reduced blood pressure during cold presser, but not during arithmetic or exercise. Mental arithmetic elicited increases in sIgA concentration and exercise produced increases in both sIg A concentration and secretion rate; these changes were unaffected by alpha blockade. In contrast the cold pressor was associated with decreases in bot h sIgA concentration and secretion rate, which were blocked by doxazosin. T hese data suggest that acute decreases, but not increases, in sIgA are medi ated by alpha-adrenergic mechanisms.