Elevated plasma immunoreactive neuropeptide Y concentrations and its increased urinary excretion in patients with advanced diabetic nephropathy

Neuropeptide Y (NPY) is a potent vasoconstrictor peptide that is abundant i n the brain and the peripheral sympathetic nervous system. In the present s tudy we investigated possible changes in plasma immunoreactive (IR)-NPY con centrations and urinary IR-NPY excretion in patients with noninsulin depend entdiabetes mellitus (NIDDM) and the relationship to diabetic complications , such as nephropathy and neuropathy. IR-NPY in plasma and urine was measur ed by radioimmunoassay in 69 patients with NIDDM. Plasma IR-NPY concentrati ons in patients with advanced nephropathy (creatinine clearance <30 ml/min) (100.5 +/- 10.3 pmol/l, n=9, mean +/- SEM) were higher than in the control subjects (55.0 +/- 6.8 pmol/l, n=15) (P<0.02). Urinary excretion of IR-NPY and fractional excretion of NPY were also increased in the patients with a dvanced nephropathy. Sephadex G-50 column chromatography of the urine extra cts obtained from healthy subjects, diabetic patients with renal failure an d non-diabetic patients with renal failure showed an immunoreactive peak el uting in the NPY position. On the other hand, neither plasma nor urinary IR -NPY was high in patients with retinopathy, or in patients with peripheral neuropathy. The present study has, for the first time, shown high plasma IR -NPY concentrations and urinary IR-NPY excretion in NIDDM patients with adv anced nephropathy.