O. Hamdy et al., Contribution of nerve-axon reflex-related vasodilation to the total skin vasodilation in diabetic patients with and without neuropathy, DIABET CARE, 24(2), 2001, pp. 344-349
OBJECTIVE- To examine the contribution of nerve-axon reflex-related vasodil
ation to total acetylcholine-induced vasodilation in the skin of normal and
diabetic subjects.
RESEARCH DESIGN AND METHODS- The skin microcirculation was evaluated at the
forearm level in 69 healthy subjects and 42 nonneuropathic diabetic patien
ts and at the foot level in 27 healthy subjects and 101 diabetic patients (
33 with neuropathy 23 with Charcot arthropathy, 32 with peripheral vascular
disease and neuropathy, and 13 without complications). Two single-point la
ser probes were used to measure total and neurovascular vasodilation respon
se to the iontophoresis of 1% acetylcholine, 1% sodium nitroprusside, and d
eionized water.
RESULTS- The neurovascular response to acetylcholine was significantly high
er than the response to sodium nitroprusside and deionized water (P < 0.01)
. At the forearm level, the contribution of neurovascular response to the t
otal response to acetylcholine was 35% in diabetic patients and 31% in cont
rol subjects. At the foot level, thf contribution was 29% in diabetic patie
nts without neuropathy and 36% in control subjects, while it nas significan
tly diminished in the three neuropathic groups. A significantly lower nonsp
ecific nerve-axon-related vasodilation was observed during the iontophoresi
s of sodium nitroprusside, which does nut specifically stimulate the C noci
ceptive fibers.
CONCLUSIONS- Neurovascular vasodilation accounts for approximately one-thir
d of thr total acetylcholine-induced vasodilation at both the forearm and f
oot levels. The presence of diabetic neuropathy results in reduction of bot
h the total vasodilatory response to acetylcholine and the percentage contr
ibution of neurovascular vasodilation to the total response. Acetylcholine
and sodium nitroprusside cause vasodilation in the skin microcirculation th
rough different pathways.