Effect of H+ extracellular and intracellular buffering capacity on the activity Ca2+/H+ exchange in the lymphocyte plasma membrane

Formation of delta pH is registered when studying Ca2+ passive transport through lymphocytes' plasma membrane (PM). The pHi values strongly depended on pH0. Changes of pH0 lead to unidirectional changes of pHi and affect Ca2+ concentration in cytoplasm of the intact cells. The presence of Ca(2+)-channels antagonists does not affect this phenomenon. Ca2+/H+ exchange is supposed to exist in PM. It is also of great interest that cytoplasmic Ca2+ and H+ activities are some equal in physiological range. Besides, H(+)-buffering as well as Ca(2+)-buffering systems are present in the cell and have their maximal capacity about 7.2 in the intact cells. The spectrofluorimetric study of internal lymphocytes' H(+)-buffering capacity with titration technique using weak base, acid or other buffer addition has demonstrated maximal value of 9.0-1.1 mM depending on the substance to be added.