Sex-dependent changes in plasma globulins in women and men exposed to heat stress.

Healthy, sedentary women and men, aged 20 to 30 years, were exposed to the same degree of intermittent heat stress in a sauna bath. Blood samples were taken immediately before and at various intervals after heat exposure. The concentrations and intravascular masses of IgG, IgA, IgM, alpha1-antitrypsin, transferrin and alpha2-macroglobulin were determined by the radial immunodiffusion technique and by the measurement of plasma volume. Losses in body weight and plasma volume were lower in women than in men. The globulin concentrations increased significantly in both sexes after heat exposure. The sum of the masses of individual globulins increased only in women, a change interpreted as globulin shifts from the interstitial into the vascular space. Whereas it is unlikely that sex-dependent differences in these shifts are due to changes in vascular permeability, it seems that the protein composition of the lymphatic fluid entering the vascular space plays an important role in these shifts.