Contribution of Nerve-Axon Reflex-Related Vasodilation to the Total Skin Vasodilation in Diabetic Patients With and Without Neuropathy
- Osama Hamdy, MD,
- Karim Abou-Elenin, MD,
- Frank W. LoGerfo, MD,
- Edward S. Horton, MD and
- Aristidis Veves, MD
- From the Clinical Research Center (O.H., K.A.-E., E.S.H.), Joslin Diabetes Center, Department of Medicine, and the Joslin—Beth Israel Deaconess Foot Center and Microcirculation Laboratory (F.W.L., A.V.), Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts.
- Address correspondence and reprint requests to Aristidis Veves, MD, Microcirculation Laboratory, Palmer 317, West Campus, Beth Israel Deaconess Medical Center, One Deaconess Road, Boston, MA 02215. E-mail: aveves{at}caregroup.harvard.edu .
Abstract
OBJECTIVE— To examine the contribution of nerve-axon reflex-related vasodilation 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 patients 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 laser probes were used to measure total and neurovascular vasodilation response to the iontophoresis of 1% acetylcholine, 1% sodium nitroprusside, and deionized water.
RESULTS— The neurovascular response to acetylcholine was significantly higher than the response to sodium nitroprusside and deionized water (P < 0.01). At the forearm level, the contribution of neurovascular response to the total response to acetylcholine was 35% in diabetic patients and 31% in control subjects. At the foot level, the contribution was 29% in diabetic patients without neuropathy and 36% in control subjects, while it was significantly diminished in the three neuropathic groups. A significantly lower nonspecific nerve-axon-related vasodilation was observed during the iontophoresis of sodium nitroprusside, which does not specifically stimulate the C nociceptive fibers.
CONCLUSIONS— Neurovascular vasodilation accounts for approximately one-third of the total acetylcholine-induced vasodilation at both the forearm and foot levels. The presence of diabetic neuropathy results in reduction of both the total vasodilatory response to acetylcholine and the percentage contribution of neurovascular vasodilation to the total response. Acetylcholine and sodium nitroprusside cause vasodilation in the skin microcirculation through different pathways.
Footnotes
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Abbreviations: CV, coefficient of variation.
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A table elsewhere in this issue shows conventional and Système International (SI) units and conversion factors for many substances.
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- Accepted October 19, 2000.
- Received July 6, 2000.
- by the American Diabetes Association, Inc.
