COMPARISON OF DIRECTLY STIMULATED WITH AXON-REFLEX MEDIATED SUDOMOTORRESPONSES IN HUMAN-SUBJECTS AND IN PATIENTS WITH DIABETES

The muscarinic receptors of human eccrine sweat gland may be directly stimulated by iontophoresis of acetylcholine (direct response; DIR) an d indirectly via nicotinic receptors and an axon ''reflex'' (AXR). Usi ng a specially designed multicompartmental sweat cell and dual sudorom eters, we were able to simultaneously record the evoked DIR and AXR re sponses. On a second day, we repeated the experiment under identical a mbient and stimulus conditions but instead obtained silastic imprints of DIR and AXR for morphometry. Studies were done on 24 controls (mean +/- SD = 47.6 +/- 15.1 years) and 23 diabetic subjects (mean +/- SD = 49.6 +/- 16.3 years). In control subjects, sudorometric DIR recording s were consistently larger than AXR. There was no difference in sweat droplet density by sex, but the size of droplets was larger in males. In diabetic patients 3 of 23 had absent AXR but preserved DIR, suggest ing that failure of AXR preceded DIR in patients with neuropathy. Pati ents with mild neuropathy had an overrepresentation of large diameter droplets in the silastic imprints of both DIR and AXR, while patients with severe neuropathy had a markedly reduced density and small diamet er droplets.