Table 4. Incorporation of ¹⁴C from glucose or pyruvate into various lipid fractions in INS-1 cells.

INS-1 832/13 cells were incubated in suspension in the presence of [2-¹⁴C]pyruvate or [U¹⁴C]glucose for 30 min. The control condition was 1 mM glucose which is the only condition shown that does not stimulate insulin release from INS-1 832/13 cells. There was 1.5 mg cell protein per test tube. In our laboratory, the relative insulin release in INS-1 832/13 cells caused by 1 mM pyruvate, 5 mM pyruvate and 10 mM glucose is 10–20, 12–25 and 10–25 fold the 1 mM glucose control, respectively [12 and MJM, unpublished data]. Results are the mean ± SE of three replicate incubations for each condition. Incorporation of carbon into phosphatidyl serine was not detected. All values for 5 mM pyruvate and 10 mM glucose were significantly different from the 1 mM glucose control values with p ≤ 0.001 to p ≤ 0.05.

	Secretagogues
	1 mM Glucose	1 mM Pyruvate	5 mM Pyruvate	10 mM Glucose
	Pyruvate or Glucose Incorporated [pmol pyruvate or glucose/sample)
	Incubation Condition
Fatty Acid Class
Cholesterol Ester	5.8 ± 0.3	12 ± 0.7	32 ± 0.4	82 ± 1.4
Triglyceride	13.5 ± 0.6	28 ± 0.6	100 ± 3	340 ± 5.2
Free Fatty Acids	5.4 ± 0.3	52 ± 2.3	210 ± 1.4	67 ± 1.3
Diacylgliceride	3.5 ± 0.2	5.5 ± 0.1	20 ± 0.3	60 ± 0.8
Phospholipids	84 ± 7.3	61 ± 0.10	200 ± 10	980 ± 33
Phosphatidyl-choline	50 ± 3.4	45 ± 1.5	181 ± 4	480 ± 6.6
Pholphatidyl-ethanolamine	2.3 ± 0.1	1.2 ± 0.1	6.2 ± 0.3	31 ± 0.3
Phosphatidyl-inositol	4.5 ± 0.2	12 ± 0.7	46 ± 0.9	110 ± 1.3
Sphingomyelin	11 ± 0.3	11 ± 4.8	18 ± 1.7	200 ± 1.8