New analgesic assay utilizing trypsin-induced hyperalgesia in the hind limb of the rat.

Subplantar injection of 250 micrograms of trypsin in the rat resulted in a biphasic increase in pain sensitivity (hyperalgesia) with peaks at 10 and 150 min separated by a period of decreased sensitivity to pain (hypoalgesia). Hyperalgesia was assessed by a decrease in response latency to a 3.0-kg force applied to the injected hind limb.

Nucleosides of azathioprine and thiamiprine as antiarthritics.

Azathioprine [Imuran; 6-[(1-methyl-4-nitro-1H-imidazol-5-yl)thio]-1H-purine] is a widely used immunosuppressive and antiarthritic drug. For the sake of comparison, the riboside, the 2'-deoxyriboside, and the arabinoside of azathioprine and its 2-amino congener, thiamiprine, were prepared by an enzymatic method. In vitro, the cytotoxicities of these aglycons and their nucleosides were similar (ED50 = 0.

Pharmacological characterization of the algesic response to the subplantar injection of serotonin in the rat.

Subplantar injection of 0.10 micrograms of serotonin in the rat resulted in a brief period (0-20 min) of increased pain sensitivity to an applied force (hyperalgesia) which preceded a longer period (40-120 min) of decreased pain sensitivity (hypoalgesia). The magnitude of each of these changes and the duration of the hypoalgesia were dose-dependent.

Pathway to carrageenan-induced inflammation in the hind limb of the rat.

A sequential 43-step pathway scheme for the inflammatory response of the rat to interdermal injection of carrageenan (C) was devised. It consisted of a nonphagocytic inflammatory response (NPIR) followed by a phagocytic inflammatory response (PIR) in the dermis and an epidermal NPIR. The dermal NPIR comprised edema, hyperemia, and hyperalgesia followed by hypoalgesia.