Palytoxin: effects on contractility and 45Ca2+ uptake in isolated ventricle strips.
Palytoxin (PTX) inhibited phasic tension production and initiated tonic contracture in isolated paced ventricle strips at concentrations greater than 10(-10) M. PTX-induced contracture was associated with increased 45Ca2+ uptake. PTX-induced additional 45Ca2+ uptake was completely blocked by 2 mM La3+. All observed PTX effects were enhanced by elevation of [Ca2+] o from 1.9 to 6 mM and this threefold increase in [Ca2+] o resulted in a threefold increase in isotope-determined Ca2+ uptake in presence of 10(-8) M PTX. It is concluded that the observed effects of PTX could be mediated by an increase in calcium permeability of myocardial cells.
D000178:Acrylamides / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002132:Calcium Radioisotopes; D003064:Cnidarian Venoms; D006352:Heart Ventricles; D066298:In Vitro Techniques; D007811:Lanthanum / Q000494:pharmacology; D008297:Male; D008387:Marine Toxins / Q000494:pharmacology*; D009200:Myocardial Contraction / Q000187:drug effects*; D009206:Myocardium / Q000378:metabolism*; D011817:Rabbits; D051381:Rats; D013997:Time Factors; D000095702:Polyether Toxins
D000178:Acrylamides; D002118:Calcium; D002132:Calcium Radioisotopes; D003064:Cnidarian Venoms; D007811:Lanthanum; D008387:Marine Toxins; C010272:palytoxin; D000095702:Polyether Toxins