Table 2.

Effect of insulin on L-arginine transport in HUVECs.

	L-Arginine transport kinetics
	Vmax (pmol/ μg protein/min)	Km (μM)	Vmax/Km (pmol/ μg protein/min/(μM))
Control	1.7±0.4	88±23	0.019±0.005
Insulin 1 min	2.7±0.9	84±18	0.032±0.008
Insulin 2 min	2.3±0.7	130±22	0.017±0.004
Insulin 3 min	3.7±1.7*	145±28	0.025±0.007
Insulin 5 min	3.4±1.0*	70±12	0.049±0.018*
Insulin 10 min	1.2±0.4	54±16	0.022±0.007
Insulin 20 min	1.5±0.6	84±12	0.010±0.003
Insulin 30 min	9.1±1.1*	153±18	0.059±0.007*

Kinetics of saturable L-arginine transport (0–250 μM L-arginine, 2 μCi/ml L-[³H]arginine, 1 min, 37°C) was measured in HUVECs exposed (1–30 min) to Krebs solution in absence (Control), or containing 1 nM insulin (see Methods). Maximal transport capacity was determined by the V_max/K_m ratio for L-arginine transport.

^*P < 0.05 versus control. Values are means ± SEM (n = 10–12).