1. Toxins from invertebrates have proved useful tools for investigation of the properties of ion channels. In this study we describe the actions of arginine polyamine which is believed to be a close analogue of FTX, a polyamine isolated from the American funnel web spider, Agelenopsis aperta. 2. Vol...

Intracerebroventricular (i.c.v.) administration of morphine produces antinociception which is antagonized by intrathecal (i.t.) injection of adenosine receptor antagonists, suggesting that adenosine release from the spinal cord may partially mediate antinociception produced by supraspinal morphine. ...

5-Hydroxytryptamine (5-HT) releases a purine nucleotide, which is subsequently converted to adenosine, from primary afferent nerve terminals in vitro. This release may mediate spinal antinociception by 5-HT. In the present study, we have investigated whether release also occurs from the spinal cord ...

Spinal analgesia produced by morphine is blocked by methylxanthine adenosine receptor antagonists. In biochemical studies, morphine releases adenosine from spinal cord synaptosomes prepared from the dorsal spinal cord, as well as from the intact spinal cord in vivo. Adenosine release is reduced by i...

In the present study the neuronal source of adenosine released by K+, morphine and norepinephrine (NE) from the spinal cord was investigated. Intrathecal pretreatment with 5,7-dihydroxytryptamine and 6-hydroxydopamine reduced spinal 5-hydroxytryptamine and NE levels, respectively, but had no effect ...

Intrathecal (i.t.) pretreatment of rats with either theophylline (50 micrograms) or 8-phenyltheophylline (3 micrograms) antagonized antinociception produced by i.t. injection of morphine (0.3-3 micrograms) in the tailflick and hotplate tests, but had no effect on antinociception produced by i.t. inj...

Substance P (SP), injected intrathecally, produced a dose-related increase in responsiveness (hyperalgesia) in a pressure test for nociceptive thresholds. Pretreatment with two doses of SP produced complete desensitization to this response but did not alter base-line responsiveness. The hyperalgesic...

The overproduction of reactive oxygen species (ROS) and reactive nitrogen species (RNS) is a common underlying mechanism of many neuropathologies, as they have been shown to damage various cellular components, including proteins, lipids and DNA. Free radicals, especially superoxide (O(2)*-), and non...

The identity and role of G proteins in coupling adenosine receptors to effectors have been studied to a limited degree. We have identified the G proteins whose GTPase activity is stimulated by adenosine receptor agonists in neuronal membranes. (R)-Phenylisopropyladenosine, 2-chloroadenosine, and N-e...

Analogues of adenosine were injected intrathecally into rats implanted with chronic indwelling cannulae in order to determine a rank order of potency and hence characterize adenosine receptors involved in spinal antinociception. In the tail flick test L-N6-phenylisopropyl adenosine (L-PIA), cyclohex...

Several lines of evidence suggest that L-type Ca2+ channels (1,4-dihydropyridine receptors) are modulated by GTP-binding proteins. We have further examined this interaction by measuring the effect of 1,4-dihydropyridines on GTPase activity in brain membranes. Dihydropyridine agonists significantly i...