title: Contractile effects of jellyfish toxin extracted from Carybdea rastonii on isolated rabbit aorta.
abstract: Effects of the toxic component of jellyfish (Carybdea rastonii) (pCrTX) on the smooth muscle tension of isolated rabbit thoracic aorta were examined. pCrTX, at concentrations higher than 10(-7) g/ml, caused slowly developing tension that reached its maximum after about 1 hr. This contraction was partially inhibited by pretreatment of the tissue with phentolamine (5 X 10(-6) M) or indomethacin (10(-5) M). The contraction induced by pCrTX was partially inhibited by nicardipine (10(-7) M) and markedly augmented by Bay k8644 (10(-6) M). In low-Na+ solution, the rate of rise of the pCrTX-induced contraction was significantly reduced. Removal of external Ca2+ inhibited the pCrTX-induced contraction by about 30%, while chlorpromazine, trifluoperazine, prenylamine and papaverine (10(-4) M) completely inhibited the contraction. pCrTX itself did not cause any contraction in saponin-skinned smooth muscle and had no effect on the Ca2+-induced contractile tension. It has been reported that pCrTX-induced contraction is attributable to the release of endogenous catecholamines and also to the increase in Ca2+ influx in smooth muscle (Azuma et al., 1986). The present results confirmed the previous suggestion and further suggested that a portion of the contraction is due to release of prostaglandin(s) and also to the direct effect on smooth muscle which is not dependent on Ca2+ influx.
mesh_terms: D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects; D002746:Chlorpromazine / Q000494:pharmacology; D003064:Cnidarian Venoms / Q000494:pharmacology*; D004347:Drug Interactions; D066298:In Vitro Techniques; D007213:Indomethacin / Q000494:pharmacology; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D009529:Nicardipine / Q000494:pharmacology; D010646:Phentolamine / Q000494:pharmacology; D011817:Rabbits
chemical_list: D003064:Cnidarian Venoms; D009529:Nicardipine; D002746:Chlorpromazine; D007213:Indomethacin; D010646:Phentolamine