Generalised metabolic and electrolyte disturbances are known to accompany both plasma and surface virus infections. We have investigated whether these infections could impair the transport of Ca2+ from cells under conditions of controlled concentrations of the energy substrate glucose. Thus, cytosolic calcium levels ([Ca2+]i) were measured in single isolated lymphocytes obtained from healthy volunteers or those suffering from coryza. Before making measurements using a Ca(2+)-sensitive fluorescent dye indo 1, we incubated lymphocytes in buffers containing 0 mM-, 5.6 mM- or 11.2 mM-[glucose]. We found that [Ca2+]i of lymphocytes obtained from the sick were significantly higher than those from healthy controls both at 0 mM and 5.6 mM-[glucose], and that [Ca2+]i was inversely related to the media glucose concentration for both groups. These results suggest a diminished capacity of cation pumping in viral infections, such as coryza, in relationship to the available glucose as energy substrate.