Objective        To determine the effect of methyl-β-cyclodextrin (MβCD) on the change of in

tracellular calcium cation concentrations induced by endothelin-1 (ET-1) in rat internal carotid artery vascular smooth muscle cells (VSMCs).       Methods        The primary cultured rat internal carotid artery VSMCs were identified by morphological observation and immunofluorescence staining. The obtained VSMCs were treated by MβCD (5 mmol/L)

TNF-α(100 μg/L)

and combined treatment

and the cells without treatment served as control. The 4 groups of cells were then stimulated by ET-1 (100 nmol/L) in physiological saline solution (PSS). After the staining of Ca

2+

-sensitive dye Fluo-2/AM

TILL photonics spectrofluorometry was used to measure the fluorescence ratio (R

F340/F380) for the intracellular calcium changes.       Results        Without ET-1 stimulation

there was no difference in the fluorescence ratio (R

0

) of VSMCs in the control

and MβCD

TNF-α and combined treatment cells (0.591 6±0.082 0

0.575 3±0.079 0

0.655 1±0.083 7

0.610 5±0.080 4

P

>0.05).After 100 nmol /L ET-1 stimulation

the ratio (R) was increased by (115±17)% in the control

and by (67±15)% in the cells treated by MβCD

with significant between the 2 groups (

P

<

0.05). The ratio was elevated by (279±21)% in the cells treated by TNF-α and by (88±16)％ in those with combined treatment after the same stimulation. Significant differences were seen between the cells treated by TNF-αand control

P

<

0.01)

and between the combined treatment cells and the cells treated by TNF-α (

P

<

0.01).       Conclusion        MβCD destroys caveolae structure and then obviously reduces the ET-1-increased intracellular calcium cation concentration in rat internal carotid artery VSMCs

and the caveolae may be a potential target for preventing cerebral vasospasm.