Blockade by nickel ions of phasic contraction to K+ and high affinity calcium of ileal longitudinal muscle of guinea-pig.
1. Preincubation with 1 or 2 mM Ni2+ inhibited dose-dependently the ileal phasic response to K+ (60 mM) without appreciable effects on the tonic response. Ni2+ above 3 mM inhibited the tonic response. 2. Ni2+ inhibited the high affinity Ca2+ sites than the low affinity sites during K+ contraction. 3. After treatment with Ni2+, the K+ response was fairly restored by a wash with normal medium. The nickel bound to the ileal cells was almost eliminated with the washing. 4. This probably indicates that Ni2+ mainly inhibited the K(+)-induced phasic tension by reducing Ca2+ release rather than Ca2+ influx.
Nasu
T
T
Department of Veterinary Pharmacology, Faculty of Agriculture, Yamaguchi University, Japan.
Yamaguchi
K
K
Shibata
H
H
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D006168:Guinea Pigs; D007082:Ileum / Q000187:drug effects*; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009532:Nickel / Q000494:pharmacology*; D011188:Potassium / Q000494:pharmacology*
D009532:Nickel; D011188:Potassium; D002118:Calcium