[Pain reception in the skin studied with chemical agents].

Cutaneous C-fibre polymodal mechano-heat (CMH) sensory units of narcotized cats have been studied for their responses to the close-arterial injection of potassium, acetylcholine and methacholine to the saphenous artery in subnoxious and noxious concentrations. Subnoxious chemical stimulation has induced low-frequency excitation of CMH units. The parameters of CMH units firing during subnoxious and noxious chemical stimulation may be used for estimation of effects of local anesthetics.

[Selective electric-current inhibition of signals from the C fibers in nerve fiber microbundles: a method for identifying A and C afferents].

Direct electric current of 3 microA applied through platinum electrode during 10 s to a fine strand teased mechanically from saphenous nerve, inhibits selectively C-fibre spikes in the strand and does not inhibit A-fiber spikes. The selective inhibition of C-fibers spikes in a fine strand is proposed as a method to identify a type of a single nerve fiber.

[Differences in the excitatory action of acetylcholine and mecholine on mechanosensitive high-threshold C-axonal units of the skin in the cat].

Intraarterial acetylcholine (Ach) and acetyl-beta-methylcholine (metacholine, Mch) excite feline high-threshold C-fiber mechanosensitive cutaneous sensory units (SU) in a different way. Ach in noxious (algogenic for humans) concentrations of 10 micrograms/ml and more induces a high-frequency discharge, with mean frequency of impulses at its peak being 4-12 Hz. This discharge seems to result from activation of N-cholinoreceptors because non-noxious and nonalgogenic M-agonist Mch as well as Ach in subnoxious concentrations induce in SU only a low-frequency discharge with a mean frequency of impulses 0.

[Excitation of mechanosensitive C-fiber sensory units of the skin in the cat by the intra-arterial administration of potassium ions].

In anaesthetized cats the responses of low- and high-threshold mechanosensitive C-fiber sensory units (MSU) in n. saphenus to close-arterial injection of potassium ions in subnoxious and noxious concentrations (SC and NC) have been studied. Two groups of high-threshold MSU were found: 1) MSU excited by K+ in NC only and 2) MSU responded to K+ both in SC and NC.

[Separation of undamaged single nerve fibers by using an ultrasonic microscalpel].

A routine procedure for dissection of single nerve fibres with sharpened sewing needles is rather tiresome and occasionally traumatic because of poor efficiency in cutting interfibrous connective tissue and sticking out patches of it to preparative needles. The described method using microscalpel oscillating with ultrasonic frequency is free from these shortcomings. Voltage clamp tests proved an innocuous character of this method for excitable nodal membrane.