Antitussive activity of iodo-resiniferatoxin in guinea pigs.
BACKGROUND
Iodo-resiniferatoxin (I-RTX) has recently been described as an ultra potent antagonist of the transient receptor potential vanilloid-1 (TRPV1).


METHODS
The ability of I-RTX to inhibit cough induced by inhalation of two putative TRPV1 stimulants (capsaicin and citric acid) was tested in non-anaesthetised guinea pigs.


RESULTS
Pretreatment with I-RTX either intraperitoneally (0.03-0.3 micromol/kg) or by aerosol (0.1-3 microM) reduced the number of coughs produced by inhalation of citric acid (0.25 M) and capsaicin (30 microM) in a dose dependent manner. Capsazepine (CPZ) also reduced citric acid and capsaicin induced cough, but the activity of I-RTX was 10-100 times more potent than CPZ in all the experimental conditions tested.


CONCLUSIONS
I-RTX is a novel and potent antitussive drug which inhibits cough mediated by agents possibly acting via TRPV1 activation.
Trevisani
M
M
Center of Excellence for the Study of Inflammation, University of Ferrara, Ferrara, Italy. tvm@unife.it
Milan
A
A
Gatti
R
R
Zanasi
A
A
Harrison
S
S
Fontana
G
G
Morice
A H
AH
Geppetti
P
P
D000818:Animals; D000996:Antitussive Agents / Q000627:therapeutic use*; D003371:Cough / Q000517:prevention & control*; D004224:Diterpenes / Q000627:therapeutic use*; D006168:Guinea Pigs; D007473:Ion Channels; D008297:Male; D011955:Receptors, Drug / Q000037:antagonists & inhibitors*; D050916:TRPV Cation Channels
D000996:Antitussive Agents; D004224:Diterpenes; D007473:Ion Channels; D011955:Receptors, Drug; D050916:TRPV Cation Channels; C476722:Trpv2 protein, rat; C468130:iodoresiniferatoxin