INCREASE IN SKELETAL-MUSCLE BLOOD-FLOW BUT NOT IN RENAL BLOOD-FLOW DURING EUGLYCEMIC HYPERINSULINEMIA IN MAN

In order to investigate the effect of euglycemic hyperinsulinemia on s keletal muscle blood flow and renal blood flow, catheters were inserte d into both femoral arteries, one femoral vein and one renal vein of 7 healthy men. Constant infusions of indocyanine-green dye (intra-arter ial) and of p-aminohippuric acid (intra-venous) were used to estimate leg plasma flow (ELPF) and renal blood flow (ERPF), respectively, prio r to and during a euglycemic, hyperinsulinemic clamp (1.0 mU/kg . min of human insulin, serum concentrations of insulin before and during th e clamp: 4.6+/-0.9 muU/ml and 65.5+/-20.6 muU/ml, respectively, t = 12 0 min). ERPF (basal: 1220+/-320 ml/min) remained unchanged throughout the period of induced hyperinsulinemia in each volunteer (mean: 1135+/ -490 ml/min), whereas mean leg plasma flow (ELPF) rose from, basal, 20 6+/-99 ml/min up to 275 ml/min 90 minutes after the beginning of the e uglycemic clamp study (p<0.01). This was due to the marked rise in ELP F from 149+/-24 ml/min up to 243+/-25 ml/min (p<0.01) seen in 5 subjec ts. In two men, who presented a markedly higher basal ELPF (332 and 36 5 ml/min, respectively), no further rise in ELPF was seen during induc ed hyperinsulinemia. Fractional renal extraction of insulin was unchan ged during induced hyperinsulinemia (28+/-5 %; basal: 22+/-18 %), as w as fractional extraction of insulin by the leg (10+/-5 %; basal: 13+/- 11 %). The observed dissociation of ERPF and ELPF suggests a different ial response to insulin in renal vs. leg vasculature which possibly is due to increased peripheral glucose metabolism.