Antagonistic effects of berbamine on [Ca2+]i mobilization by KCl, norepinephrine, and caffeine in newborn rat cardiomyocytes.
OBJECTIVE
To study the effects of berbamine (Ber) on intracellular calcium concentration ([Ca2+]i) mobilized by KCl depolarization, norepinephrine (NE), and caffeine.


METHODS
[Ca2+]i was measured with fluorescent intensity (FI) by confocal microscope in single cultured cardiomyocytes of newborn rats loaded with Fluo 3-AM 2 mumol.L-1.


RESULTS
FI value of [Ca2+]i in control level was 248 +/- 70 in the presence of extracellular calcium 1.5 mmol.L-1 and was not changed by Ber 3-30 mumol.L-1. KCl (60 mmol.L-1)- and NE (30 mumol.L-1)-induced [Ca2+]i mobilizations were inhibited (P < 0.01) by Ber 30 mumol.L-1, similar to that of verapamil (Ver). The inhibitory effect of Ber on [Ca2+]i induced by KCl was further increased (P < 0.05) in the presence of egtazic acid 3 mmol.L-1, but that on [Ca2+]i induced by NE was not changed. The [Ca2+]i mobilized by caffeine 80 and 160 mumol.L-1 in D-Hanks' solution was not affected (P > 0.05) by Ber and Ver.


CONCLUSIONS
Ber possessed the antagonistic effects on [Ca2+]i increases via voltage-dependent Ca2+ channel and receptor-operated Ca2+ channel in newborn rat cardiomyocytes, but without effect on intracellular Ca2+ release.
Qiao
G F
GF
Department of Pharmacology, Harbin Medical University, China.
Zhou
H
H
Li
B Y
BY
Li
W H
WH
D000470:Alkaloids / Q000494:pharmacology*; D000818:Animals; D000831:Animals, Newborn; D044182:Benzylisoquinolines; D001693:Biological Transport, Active; D002110:Caffeine / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002478:Cells, Cultured; D009206:Myocardium / Q000166:cytology / Q000378:metabolism*; D009638:Norepinephrine / Q000494:pharmacology*; D011189:Potassium Chloride / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar
D000470:Alkaloids; D044182:Benzylisoquinolines; D002121:Calcium Channel Blockers; D002110:Caffeine; D011189:Potassium Chloride; D002118:Calcium; C027870:berbamine; D009638:Norepinephrine