[Calcium channel mechanism by which betaine promotes proliferation of lymphocytes in mice].
OBJECTIVE
To study how the way in which betaine promotes the proliferation of mouse spleen lymphocytes is related to calcium channels.


METHODS
BALB/c mice were used for this experiment. Mouse spleen lymphocytes were obtained through in vitro cultivation after they had been separated, and were divided into a negative control group, a Con A group, and 0.04, 0.4, 4, and 20 mmol x L(-1) betaine groups. MTT was used to observe the effect of betaine on the proliferation of mouse spleen lymphocytes; flow cytometry was used to measure the changes in the cell cycle of mouse spleen lymphocytes; and laser confocal scanning microscopy was used to observe the changes in the intracellular [Ca2+]i of mouse spleen lymphocytes after betaine or different calcium channel blockers were applied.


RESULTS
Betaine was found to promote the proliferation of mouse spleen lymphocytes 12 h after it had been applied in vitro in concentrations of 4 and 20 mmol x L(-1). It was also found to promote the proliferation of mouse spleen lymphocytes 24 h and 48 h after it had been applied in vitro in concentrations of 0.04, 0.4, 4, and 20 mmol x L(-1), with the effect being most marked for the 4 mmol x L(-1) group 24 h after its application. It was found to facilitate the entry of mouse spleen lymphocytes from the G0/G1 to the S phase 4, 6, 18, and 24 h after it had been applied to mouse spleen lymphocytes in a concentration of 4 mmol x L(-1), with the effect being most marked at 18 h after its application. Intracellular [Ca2+]i in mouse spleen lymphocytes increased significantly (P < 0.01) 6, 12, 18 h after 4 mmol x L(-1) betaine had acted on the lymphocytes, with the effect being most marked at 6 h. The calcium channel blockers nifidipine, diltiazem, mibefradil, and genistein had no effect on the increase of the intracellular [Ca2+]i in mouse spleen lymphocytes due to the application of betaine, while verapamil, mycifradin, heparin, and procaine could block such increase.


CONCLUSIONS
Betaine facilitates the entry of mouse spleen lymphocytes from the G0/G1 into the S phase by raising the intracellular [Ca2+]i in these cells, thus promoting their proliferation. Intracellular [Ca2+]i increases mainly in two ways: (1) By affecting the alpha1 subunit of the L-type voltage-gated calcium channel with mediation by G proteins and thus leading to an efflux of intracellular calcium: (2) By affecting the IP3R and RyR calcium channels of the intracellular calcium stores and thus leading to the release of intracellular calcium.
Ji
Yubin
Y
Postdoctoral Research Station, Institute of Matetia Medica, Life Sciences and Environmental Sciences Research Center, Harbin University of Commerce, Harbin 150076, China.
Gao
Shiyong
S
Feng
Xiaoyan
X
He
Liwei
L
D000818:Animals; D001622:Betaine / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000378:metabolism*; D002453:Cell Cycle / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects*; D005260:Female; D008214:Lymphocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C
D015220:Calcium Channels; D001622:Betaine; D002118:Calcium