pyrimidinones and resiniferatoxin

The transient receptor potential (TRP) channels are important membrane sensors, responding to thermal, chemical, osmotic, or mechanical stimuli by activation of calcium and sodium fluxes. In this study, three distinct TRP channels were detected and their role established in mediating cytosolic free calcium concentration ([Ca(2+)](cyt)) response in tumor-derived SW982 synoviocytes and primary cultures of human synovial cells from patients with inflammatory arthropathies. As shown by fura-2 ratio measurements while cells were incubated in a temperature-regulated chamber, significant [Ca(2+)](cyt) elevation was elicited by rapid changes in bath temperature, application of TRPV1 receptor agonists capsaicin and resiniferatoxin, or a cold receptor stimulator, icilin. Temperature thresholds for calcium response were determined to be 12 +/- 1 degrees C for cold and 28 +/- 2 degrees C for heat activation. Temperature increases or decreases beyond these thresholds resulted in a significant rise in the magnitude of [Ca(2+)](cyt) spikes. Observed changes in [Ca(2+)](cyt) were completely abolished in calcium-free medium and thus resulted from direct calcium entry through TRP channels rather then by activation of voltage-dependent calcium channels. Two heat sensitive channels, TRPV1 and TRPV4, and a cold-sensitive channel, TRPA1, were detected by RT-PCR. Minimal mRNA for TRPV3 or TRPM8 was amplified. The RT-PCR results support the data obtained with the [Ca(2+)](cyt) measurements. We propose that the TRP channels are functionally expressed in human synoviocytes and may play a critical role in adaptive or pathological changes in articular surfaces during arthritic inflammation.

Topics: Arthritis, Rheumatoid; Calcium; Calcium Channels; Calcium Signaling; Capsaicin; Cell Line, Tumor; Cells, Cultured; Chondrocalcinosis; Cytosol; Diterpenes; Hot Temperature; Humans; Inflammation; Nerve Tissue Proteins; Pyrimidinones; RNA, Messenger; Synovial Membrane; Transient Receptor Potential Channels; TRPA1 Cation Channel; TRPM Cation Channels; TRPV Cation Channels

Arterially perfused, decerebrate preparations of the insectivore, Suncus murinus were made to determine whether the emetic reflex could be activated in such a preparation using a range of stimuli shown to be emetic in conscious or anaesthetised Suncus. Efferent phrenic and vagus nerve activities and electromyograms (EMGs) from the temporalis, abdominal oesophagus and trapezius muscles were recorded, as well as longitudinal shortening of the oesophagus and dorso-ventral movements of the thorax. The preparations swallowed spontaneously every 0.6 to 6.5 min. The duration of a swallow was 3.1 +/- 0.3 s (recorded as the time taken for the oesophagus to shorten and recover to its resting position) and the oesophagus shortened by 3.5 +/- 0.4 mm during a swallow. The emetic reflex was activated by electrical stimulation (30 Hz, 10-20 V, 0.2 ms pulse width, for 30 s) of abdominal vagal afferents (latency < 30 s) or by arterial perfusion with either 40 nM of the capsaicin analogue resiniferatoxin (latency 1.7 +/- 0.6 min), 6 microM nicotine (latency 1.6 +/- 0.1 min) or 1 microM of the phosphodiesterase IV inhibitor CP-80,633 (latency 8.9 +/- 3.9 min). These emetic stimuli produced somatic and visceral movements in Suncus preparations indicative of activation of the emetic reflex. There were pronounced contractions of the thorax that occurred simultaneously with oesophageal shortening and mouth opening, separated by thorax expansion and a burst of phrenic nerve activity. During emetic-like episodes, oesophageal shortenings were only 0.84 +/- 0.1 s in duration, faster than the duration of shortening observed during swallowing (cf. swallowing, 3.1 +/- 0.3 s; P < 0.0001). The shortening of the oesophagus during emetic-like episodes was 6.2 +/- 0.4 mm, which was greater than the shortening seen during swallowing (cf. swallowing, 3.5 +/- 0.4 mm; P < 0.0001). We conclude that the emetic reflex can be activated in our Suncus preparations and that this non-sentient small adult animal model can now be used to study the neurophysiology and pharmacology of swallowing and emesis.

Topics: Animals; Aorta, Thoracic; Decerebrate State; Deglutition; Disease Models, Animal; Diterpenes; Electric Stimulation; Esophagus; Female; Heart Rate; Male; Naloxone; Narcotic Antagonists; Nicotine; Nicotinic Agonists; Perfusion; Phrenic Nerve; Physical Stimulation; Pyrimidinones; Reflex; Respiratory Mechanics; Shrews; Vagus Nerve; Video Recording; Vomiting