Insulin-mediated increases in limb blood flow are thought to enhance glucose uptake by skeletal muscle. Using the perfused rat hindlimb, we report that macro laser Doppler flowmetry (LDF) probes positioned on the surface of muscle detect changes in muscle capillary (nutritive) flow. With this as background, we examined the effects of insulin and adrenaline (epinephrine), which are both known to increase total leg blood flow, on the LDF signals from scanning and stationary probes on the muscle surface in viva. The aim is to assess the relationship between capillary recruitment, total limb blood flow and glucose metabolism. Glucose infusion rate, femoral arterial blood flow (FBF) and muscle LDF, using either scanning or a stationary probe positioned over the biceps femoris muscle, were measured. With scanning LDF, animals received insulin (10 m-units · min -1 · kg -1), adrenaline (0.125 μg · min -1 · kg -1) or saline. By 1 h, insulin had increased the glucose infusion rate from 0 to 128 μmol · min -1 · kg -1 and the scanning LDF had increased by 62 ± 8% (P < 0.05), but FBF was unaffected. Adrenaline increased FBF by 49% at 15 min, but LDF was unchanged. With saline at 1 h, neither FBF nor LDF had changed. With the stationary LDF surface probe, insulin at 1 h had increased FBF by 47% (P < 0.05) and LDF by 47% (P < 0.05) relative to saline controls. Adrenaline increased FBF (39%), but LDF was unaltered. The stimulation of LDF by insulin is consistent with capillary recruitment (nutritive flow) as part of the action of this hormone in vivo. The recruitment may be independent of changes in total flow, as adrenaline, which also increased FBF, did not increase LDF. The time of onset suggests that LDF closely parallels glucose uptake. Thus, depending on probe design, measurement of muscle haemodynamic effects mediated by insulin in normally responsive and insulin-resistant patients should be possible.

Item Type:	Refereed Article
Research Division:	Biomedical and Clinical Sciences
Research Group:	Clinical sciences
Research Field:	Endocrinology
Objective Division:	Health
Objective Group:	Clinical health
Objective Field:	Clinical health not elsewhere classified
UTAS Author:	Clark, ADH (Mr Andrew Clark)
UTAS Author:	Rattigan, S (Professor Stephen Rattigan)
UTAS Author:	Wallis, MG (Ms Michelle Gaye Wallis)
UTAS Author:	Clark, MG (Professor Michael Clark)
ID Code:	21977
Year Published:	2001
Web of Science® Times Cited:	45
Deposited By:	Biochemistry
Deposited On:	2001-08-01
Last Modified:	2002-05-10
Downloads:	0