Effects of sucrose- or Tris-substitution for Na+ on responses to D 600, papaverine and KCN in the K+-depolarized taenia coli of guinea pigs.
Effects of D 600, papaverine and KCN on sustained contracture induced by 20 mM KCl in a Na+-free sucrose- or Tris-substituted solution were investigated in the taenia coli of guinea pigs. D 600 (10(-5) M) and papaverine (10(-4) M), added after 40 min incubation in the 20 mM KCl sucrose solution, relaxed the muscle by 88.2 +/- 8.0% (mean +/- S.E., n = 4) and 78.8 +/- 6.3% (n = 4), respectively. In contrast to this, KCN (10(-3) M) relaxed the muscle by 11.0 +/- 4.7% (n = 4) after a 20 min incubation in the sucrose solution. The concentration-relaxation curves for these relaxants were slightly shifted to the right in the Na+-free 20 mM KCl Tris solution. The cellular Na+ content of the taenia coli was greatly reduced by exposure to the sucrose or Tris solution, while the Ca2+ contents in both solutions were gradually increased with the exposure time. When a glucose-free solution was applied 60 min after the KCl-induced sustained contracture, gradual relaxation in the normal solution was observed. This relaxation was completely inhibited in the Na+-free sucrose solution. These results suggest that the relaxing activities of the different inhibitors are changed to different degrees by the replacement of Na+ with sucrose in the guinea-pig taenia coli and that sustained KCl-contracture in a Na+-free sucrose solution may be less energy-dependent as compared with that in a Na+-free Tris medium.(ABSTRACT TRUNCATED AT 250 WORDS)
Kawagoe
J
J
Department of Pharmacology, Faculty of Pharmaceutical Sciences, Science University of Tokyo, Japan.
Sunagane
N
N
Uruno
T
T
Kubota
K
K
D000818:Animals; D003106:Colon / Q000187:drug effects* / Q000502:physiology; D003486:Cyanides / Q000494:pharmacology*; D005711:Gallopamil / Q000494:pharmacology*; D005947:Glucose / Q000494:pharmacology; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008297:Male; D009126:Muscle Relaxation / Q000187:drug effects; D010208:Papaverine / Q000494:pharmacology*; D011188:Potassium / Q000502:physiology; D011190:Potassium Cyanide / Q000494:pharmacology*; D012964:Sodium / Q000494:pharmacology*; D013395:Sucrose / Q000494:pharmacology; D014325:Tromethamine / Q000494:pharmacology
D003486:Cyanides; D014325:Tromethamine; D005711:Gallopamil; D013395:Sucrose; D012964:Sodium; D010208:Papaverine; D005947:Glucose; D011190:Potassium Cyanide; D011188:Potassium