Kavain inhibits murine airway smooth muscle contraction.
This study examined the effect of kavain, the principle biologically active component of kava, on murine airway smooth muscle. In isolated isometrically contracted tracheal ring preparations, kavain was noted to diminish the maximal contractile response to both muscarinic receptor activation and voltage-operated calcium channel activation. The IC50 for kavain in rings precontracted with carbachol was found to be 177 microM +/- 53.1, and, in rings precontracted with KCl, it was found to be 59.6 microM +/- 10.1. In addition, pretreatment with kavain attenuated airway smooth muscle contraction evoked with either carbachol or KCl. The EC50 for KCl was not affected by kavain pretreatment. However, the EC50 for carbachol was significantly affected by a high kavain pretreatment dose. Nitric oxide mediated relaxation was not observed to play a role in kavain's smooth muscle relaxing properties. Similarly, prostaglandin pathways are not likely involved in these effects since pretreatment of tracheal rings with indomethacin before carbachol contraction did not reduce the relaxant effect of kavain. The mechanism of kavain-induced relaxation and inhibition of contraction is likely due to a mechanism common to both contractile agonists that were employed in our study.
Martin
H B
HB
Department of Anesthesiology, University of New Mexico Health Sciences Center, Albuquerque, USA. hmartin@salud.unm.edu
Stofer
W D
WD
Eichinger
M R
MR
D000818:Animals; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects* / Q000502:physiology; D011753:Pyrones / Q000494:pharmacology*; D014132:Trachea / Q000187:drug effects* / Q000502:physiology
D011753:Pyrones; C011889:kavain