Table 1. Culture medium of cerebellar glia from Npc1^−/− and Npc1^+/+ mice accumulates the same amount of cholesterol.

Rows 1–3: glia (60% confluent) from Npc1^+/+ (WT), Npc1^+/− (Ht) and Npc1^−/− (KO) mice were radiolabelled for 3 days with [¹⁴C]acetate in DMEM containing 5% FBS. Confluent cells were then incubated for 24 h in unlabelled DMEM containing 5% FBS, washed and incubated for an additional 24 h in serum-free DMEM. Lipids were extracted from cells and medium and separated by TLC. Radioactivity/mg of protein was determined in the band corresponding to non-esterified cholesterol. Data in row 1 are expressed as amount of radioactivity in the medium as a percentage of total radioactivity in cells and medium combined. In row 2 is given the radioactivity/mg of cell protein in cells and medium combined. Row 3 shows the amount of radiolabelled [¹⁴C]cholesterol (d.p.m./mg of cell protein) in the medium. Results are means±S.E.M. for three independent experiments; *P<0.005 compared with WT. Row 4: glia were grown to confluency in DMEM containing 10% FBS then incubated for 3 days in serum-free DMEM. Medium was collected and the mass of cholesterol determined by GLC. Results are means±S.E.M. for three independent experiments.

	Value
Parameter	WT	Ht	KO
[14C]Cholesterol in medium (% of total [14C]cholesterol)	7.66±0.6	7.28±0.6	4.74±0.3*
Total [14C]cholesterol (d.p.m./mg of cell protein)	58694±1984	54342±1154	78254±4006*
[14C]Cholesterol in medium (d.p.m./mg of cell protein)	4496±232	3956±151	3710±112
Cholesterol in medium (μg/mg of cell protein)	6.20±0.61	5.63±0.37	5.54±0.87