Table 2.

Kinetic parameters for specific [³H]NBMPR binding in human umbilical artery smooth muscle cells

	Kd	Bmax
Non-diabetic
Control	0.16 ± 0.03	0.66 ± 0.07
l-NAME	0.12 ± 0.02	0.55 ± 0.01
Cycloheximide	0.12 ± 0.02	0.7 ± 0.02
SQ-22536	0.14 ± 0.03	1.3 ± 0.02*
Insulin	0.15 ± 0.01	1.1 ± 0.1*
Insulin +l-NAME	0.17 ± 0.03	0.71 ± 0.09†
Insulin + cycloheximide	0.17 ± 0.03	0.64 ± 0.04†
Insulin + SQ-22563	0.16 ± 0.01	1.1 ± 0.01*
Diabetic
Control	0.15 ± 0.03	1.62 ± 0.16*
l-NAME	0.12 ± 0.02	0.75 ± 0.11‡
Cycloheximide	0.13 ± 0.01	1.2 ± 0.1*
SQ-22536	0.14 ± 0.01	1.5 ± 0.09*
Insulin	0.18 ± 0.01	0.6 ± 0.13‡
Insulin +l-NAME	0.10 ± 0.03	0.75 ± 0.09*§
Insulin + cycloheximide	0.11 ± 0.03	0.59 ± 0.03‡
Insulin + SQ-22536	0.13 ± 0.01	1.50 ± 0.2*§

Kinetic parameters for equilibrative [³H]NBMPR binding (30 min, 22°C) were determined in smooth muscle cells incubated in medium 199 in the absence (Control) or in the presence of insulin (1nm, 8 h), N^G-nitro-L-arginine methylester (l-NAME, 100 μm, 30 min), cycloheximide (1μm, 8 h) or SQ-22536 (100 μm, 30 min), and binding was assayed in Krebs solution. Values for K_d and B_max are in nm and fmol (μg protein)⁻¹, respectively, and are the means ±s.e.m. of experiments in 3–4 different cell cultures;

^*P < 0.05 vs. corresponding control values in non-diabetic cells,

^†P< P < 0.05 vs. values in non-diabetic cells treated with insulin,

^‡P< P < 0.05 vs. corresponding control values in non-diabetic cells,

^§P < 0.05 vs. values in diabetic cells treated with insulin.