Nicardipine enhances cytoplasmic calcium concentration in mouse thymocytes in vitro.
OBJECTIVE
To study the effect of nicardipine (Nic) on the cytoplasmic free calcium concentration ([Ca2+]i) in thymocytes and on the proliferation of thymus lymphocytes from mice in vitro.


METHODS
The [Ca2+]i was measured by loading cells with the fluorescent dye Fura-2. The lymphocyte proliferation was determined by [3H] thymidine incorporation.


RESULTS
Nic 1-30 mumol . L-1 elevated [Ca2+]i of resting thymocytes with the percentages of its increase 43%-192% and 12%-148% in the presence and absence of extracellular Ca2+ respectively. Mitogen Con A 5 mg . L-1 also released Ca2+ from intracellular stores. Nic decreased the enhancement of [Ca2+]i induced by Con A. The IC50 (mumol . L-1) was 26.8 (95% limit: 24.8-29.0) and approximated to 10 in the presence and absence of extracellular Ca2+ respectively. Nic 1-30 mumol . L-1 did not stimulate the proliferation of resting lymphocytes from mouse thymuses (P > 0.05), but inhibited the proliferation when the lymphocytes had been stimulated by Con A (P < 0.01).


CONCLUSIONS
Nic elevated [Ca2+]i, which decreased the response of lymphocytes to mitogen.
Chen
W R
WR
Department of Pharmacology, Xinjiang Medical College, Urumqi.
Liu
F
F
Feng
Y J
YJ
Zhang
J T
JT
D000818:Animals; D001693:Biological Transport, Active; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D002455:Cell Division / Q000187:drug effects; D003593:Cytoplasm / Q000378:metabolism*; D005260:Female; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D009529:Nicardipine / Q000494:pharmacology*; D013601:T-Lymphocytes / Q000166:cytology / Q000378:metabolism*
D002121:Calcium Channel Blockers; D009529:Nicardipine; D002118:Calcium