Nociceptor functions in intact skin and in neurogenic or non-neurogenic inflammation

Acute neurogenic or non-neurogenic inflammation was elicited in skin patches innervated by the saphenous nerve of anaesthetized Sprague Dawley rats. Lambda carrageenan was used to induce non-neurogenic inflammation, mustard oil (allyl-iso-thio-cyanate) or antidromic nerve stimulation to induce neurogenic inflammation. Antidromic nerve stimulation yielded plasma extravasation but no significant sensitization of unmyelinated nociceptor units. In contrast, mustard oil and carrageenan yielded plasma extravasation and sensitization of nociceptors, though carrageenan sensitized only part of them. Sensitization resulted in ongoing spike discharges and in a shift of response curves to lower temperatures when controlled radiant heat stimuli were applied to the receptive fields. Responses to mechanical stimuli with v. FREY hairs were not significantly altered. Effects of neurogenic and non-neurogenic inflammation on unmyelinated nociceptor units are compared.     

Endothelial- and nitric oxide-dependent effects on oxidative metabolism of intact artery.

Oxidative metabolism and its possible modulation by nitric oxide (NO) was examined in endothelial-intact and endothelial-denuded segments of porcine carotid arteries. Endothelial-intact arteries displayed appropriate NO-mediated vasorelaxation to acetylcholine (ACh). Endothelial-denuded arteries demonstrated absent vasorelaxation to ACh stimulation and depressed contractile responsiveness to K(+) depolarization, which was normalized by inhibition of NO synthesis by N(omega)-nitro-L-arginine methylester (L-NAME). Confirmation that carotid arteries continued to produce NO despite removal of the endothelium was indicated by detection of NO metabolites in the incubation medium bathing the arteries. O(2) consumption and the oxidation of glucose and fatty acid were depressed in endothelial-denuded arteries. Depression of O(2) consumption and glucose oxidation was completely reversed by treatment with L-NAME. We conclude that endogenous NO produced by non-endothelial vascular cells depresses contractility, O(2) consumption, and oxidation of energy substrates in vascular smooth muscle. The endothelium may play a role in oxidative metabolism of vascular smooth muscle possibly by modulating the effects of NO produced by other cells of the vessel wall, or by other factors.     

Clinical effects of elastic bandage on neurogenic orthostatic hypotension

Neurogenic orthostatic hypotension (OH) often causes troublesome symptoms such as dizziness, syncope and falling, interfering active daily life or various therapies in rehabilitation. Nonpharmacologic measures for treating patients with OH include wearing elastic leotard, head-up tilting at night, etc. Elastic garment or antigravity suits is certainly effective, but it may be uncomfortable and not practical. Although elastic bandage (EB) bound on the lower limbs has been thought to be useful, there is few clinical report about its beneficial evidence. We investigated short-term clinical effects of commercially available EB on OH, and estimated the mechanism of its effectiveness by measuring some blood pressure-related humoral variables in neurodegenerative patients with OH.     

Sympathetic control of the forearm blood flow in man during brief isometric contractions

Experiments were performed to assess the possible neurally mediated constriction in active skeletal muscle during isometric hand-grip contractions. Forearm blood flow was measured by venous occlusion plethysmography on 5 volunteers who exerted a series of repeated contractions of 4 s duration every 12 s at 60% of their maximum strength of fatigue. The blood flows increased initially, but then remained constant at 20-24 ml X min(-1) X 100 ml(-1) throughout the exercise even though mean arterial blood pressure reached 21-23 kPa (160-170 mm Hg). When the same exercise was performed after arterial infusion of phentolamine, forearm blood flow increased steadily to near maximal levels of 38.7 +/- 1.4 ml X min(-1) X 100 ml(-1). Venous catecholamines, principally norepinephrine, increased throughout exercise, reaching peak values of 983 +/- 258 pg X ml(-1) at fatigue. Of the vasoactive substances measured, the concentration of K+ and osmolarity in venous plasma also increased initially and reached a steady-state during the exercise but ATP increased steadily throughout the exercise. These data indicate a continually increasing alpha-adrenergic constriction to the vascular beds in active muscles in the human forearm during isometric exercise, that is only partially counteracted by vasoactive metabolites.     

Two biological rhythms of perception distinguishing between intact and relatively damaged brain function in man.

A simple test of perception, the Critical Flicker Fusion threshold (CFF) was given successively for 20 mins. to 69 healthy subjects aged 7-63 and to 53 comparable neuropsychiatric patients. The latter could be divided into a functionally sick group and a group with brain damage. Auto-correlation analysis revealed significant sine-wave cycles of amplitude and ultradian frequency for the CFF mean scores and the CFF "Scatter* scores. Both cycles of recurrence showed frequencies which distinguished significantly between the total healthy subjects and the patients. Further analysis showed no difference between controls and emotionally sick patients (i.e. those with sociopathy, schizophrenia and manic depressive psychosis) but there was a highly significant difference between these three groups and patients with relatively damaged C.N.S. (i.e. those with mental deficiency, organic brain syndrome and organic dementia). Even among the control group a progressive increase in frequency of these perceptual cycles occurred with advancing age. These CFF results point to the existence of a cycle of perceptual acuity and another of vigilance in the organism. Both appear to relate to the neural integrity of the C.N.S.     

Psychogenic facial pain: presentation and treatment.

Ninety three patients took part in a two centre double blind controlled clinical trial designed to assess the efficacy of dothiepin (Prothiaden) as compared with placebo and a soft biteguard in the treatment of psychogenic facial pain. The results showed the superiority of dothiepin over placebo in achieving pain relief; 71% of patients were pain free in the dothiepin group at nine weeks compared with 47% in the placebo group. The biteguard conferred no benefit and compliance in its use was poor. Out of 84 patients followed up for 12 months, 68 (81%) became pain free. An adverse life event before development of pain, minimal previous surgical treatment, and freedom from pain at nine weeks were strong prognostic indicators for successful treatment. These results are clear evidence of the efficacy of dothiepin in psychogenic facial pain, though the drug may be needed for up to a year.