ABSTRACT
To induce arthritis, the adjuvant with heat-killed Mycobacterium tuberculosis was injected into the ankle joint in rats. Local redness, swelling, hotness, pain, and motor dysfunction of the inflamed joint (as well as mental dullness) were observed 48 h after inoculation. At this time, the maximal binding capacity (Bmax) of muscarinic receptors in limbic system was increased, while the dissociation constant (Kd) was unchanged. Injection of morphine (5 mg.kg-1) 3 times within 48 h after the inoculation resulted in a decrease of Bmax and an increase of Kd of M-receptors, together with diminution of pain and disappearance of dullness.
Subject(s)
Arthritis, Experimental/metabolism , Limbic System/metabolism , Morphine/pharmacology , Receptors, Muscarinic/metabolism , Animals , Down-Regulation , Electroacupuncture , Male , Pain/physiopathology , Pain Threshold/drug effects , Rats , Rats, WistarABSTRACT
The effect of high frequency stimulation on rate-dependent depression of depolarization of action potentials was studied with computer and standard microelectrode techniques in guinea pig papillary muscles. After increasing driving frequency from 0.5 to 6 Hz, decreases in Vmax, APA and OS were found. Changes of upstroke velocity during phase 0 between driving frequency 6 and 0.5 Hz could be described as a parabola. The rate-dependent depression of depolarization was exaggerated by tetrodotoxin (TTX), particularly during the accelerating period of phase 0. A progressive decline in Vmax, which could be fitted by a power function curve, was observed after changing driving frequency from 1 to 5 Hz. TTX significantly influenced the decline in Vmax and the regression coefficients in fitted equations.
