Increased monoamine oxidase activity and imidazoline binding sites in insulin-resistant adipocytes from obese Zucker rats

Table 1 Biological parameters of the lean and obese rats used in this study

Littermate phenotype	Lean (8)	Obese (9)
Final body weight (g at 9-10 wk)	230 ± 21	312 ± 16b
Visceral WAT weight (g)	1.8 ± 0.3	8.9 ± 1.4c
Subcutaneous WAT weight (g)	2.5 ± 0.3	13.4 ± 1.6c
Plasma levels
Insulin (UI/mL)	37 ± 2	178 ± 46b
Glucose (mmol/L)	7.7 ± 0.2	8.6 ± 0.2a
Triacylglycerols (mmol/L)	0.7 ± 0.2	1.5 ± 0.1b

Significantly different from each corresponding value in lean at:

^aP < 0.05.

^bP < 0.01.

^cP < 0.001.

mean ± SEM of the number of rats indicated in parentheses.

Table 2 Imidazoline binding sites labeled by ³H-2-(2-benzofuranyl)-2-imidazoline or ³H-idazoxan: Comparison between visceral and subcutaneous white adipose tissues of lean and obese rats

Radioligand genotype	3H-BFI		3H-idazoxan + rauwolscine 10 µmol/L
	Lean	Obese	Lean	Obese
	Visceral WAT
Bmax (fmol/mg protein)	608 ± 39	1467 ± 208c	232 ± 42	1268 ± 108c
KD (nmol/L)	8.9 ± 2.0	6.5 ± 0.5	16.9 ± 2.2	17.6 ± 2.6
proteins (µg/assay)	45 ± 6	49 ± 2	34 ± 7	46 ± 2
	Subcutaneous WAT
Bmax (fmol/mg protein)	309 ± 25	1046 ± 12c	212 ± 39	914 ± 53c
KD (nmol/L)	9.3 ± 0.8	5.7 ± 1.2	22.5 ± 2.3	16.5 ± 3.1
proteins (µg/assay)	51 ± 7	83 ± 12a	51 ± 7	83 ± 12a

Significantly different from each corresponding value in lean at:

^aP < 0.05.

^cP < 0.001.

The maximal binding value, B_max expressed as fmol/mg proteins, and affinity constant, K_D expressed as nmol/L, were calculated from three independent Scatchard plots built for each radioligand. The mean quantity of membrane proteins used per assay tube is also reported for each white adipose tissue anatomical location and radioligand.