Ca2+-induced aortic contraction in normal K+ after exposure to Ca2+- and Mg2+ -free solution.
Guinea pig and rabbit aortic rings which have been incubated in a Ca2+- and Mg2+ -free solution containing ethylene glycol bis-(beta-aminoethyl ether) N,N,N'N'-tetraacetic acid (EGTA) responded to addition of Ca2+ in a similar Ca2+ - and Mg2+ -free solution without EGTA by increasing tension gradually at first and then more sharply at Ca2+ concentrations above 2 mM. Prior addition of D 600 (10 or 50 microM) inhibited contractions to low Ca2+ concentrations, but only partially attenuated those to high Ca2+ concentrations. The resulting contraction is thought to represent Ca2+ entry from both voltage-dependent (D 600-sensitive) Ca2+ channels and Na+ -Ca2+ exchange (D 600-insensitive).
D000818:Animals; D001011:Aorta / Q000187:drug effects / Q000502:physiology*; D002118:Calcium / Q000494:pharmacology*; D004533:Egtazic Acid / Q000494:pharmacology; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008274:Magnesium / Q000494:pharmacology; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D011188:Potassium / Q000494:pharmacology*; D011817:Rabbits
D004533:Egtazic Acid; D008274:Magnesium; D011188:Potassium; D002118:Calcium