Investigation of K+ channel expression in human peripheral lymphocytes of healthy donors by means of flow cytometry

Evaluation of different types of K+ channel expression was performed in res ting and PHA (phytohemagglutinine)-activated human peripheral lymphocytes ( HPL) of healthy donors by means of flow cytometry. In resting peripheral ly mphocytes, the application of kaliotoxin (a selective blocker for voltage-d ependent K+ (K(V)) channels), K(V) resulted in pronounced depolarization of lymphocyte membrane potential, with further promotion in the presence of t hapsigargin (compound discharging Ca-i from endoplasmic reticulum). In acti vated HPL, the expression of various types of K+ channels was estimated uti lizing cell-cycle analysis data. In contrast to the resting cells, kaliotox in-induced depolarization of membrane potential in PHA-activated lymphocyte s of the G(0)/G(1) phase was not enhanced by thapsigargin and in PHA-activa ted lymphocytes of the S and G(2)/M phases we were able to observe repolari zation of membrane potential after kaliotoxin-induced depolarization of mem brane potential. Substitution of kaliotoxin for charybdotoxin (a non-select ive drug blocking both K(V) and K(Ca) channels) abrogated the above effects in PHA-activated lymphocytes. Thus, K(V) channels are active in both resti ng and activated HPLs and K(Ca) channel expression occurs with cell-cycle p rogress on PHA-induced activation of peripheral lymphocytes.