Desensitization in the innervated and in the chronically denervated soleus muscle of the mouse.
1 A study was made of desensitization in chronically denervated and in normally innervated mouse soleus muscles. 2 Very high concentrations of acetylcholine produced small contractions of the innervated muscles; these were reduced in size when the addition was repeated 1 min after wash-out. 3 Desensitization in innervated muscles was receptor specific: contractions in response to KCl and caffeine were not reduced following acetylcholine, nor did KCl produce desensitization. 4 In chronically denervated muscles non-specific desensitization was observed if acetylcholine was added in the presence of low concentrations of acetylcholine or carbachol. Contractions to KCl but not to caffeine were reduced. KCl produced a similar kind of desensitization. 5 After washing out moderate or supramaximal concentrations from the chronically denervated muscle no desensitization was observed. However, 1 min after washout of very high concentrations the muscle was non-specifically desensitized. 6 It is concluded that relatively high concentrations of acetylcholine are required to produce specific desensitization in the soleus muscle. Chronically denervated muscles, being supersensitive, show non-specific loss of sensitivity with concentrations of acetylcholine too low to produce specific desensitization.
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D002110:Caffeine / Q000494:pharmacology; D002217:Carbachol / Q000494:pharmacology; D003714:Denervation; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D009119:Muscle Contraction / Q000187:drug effects*; D009132:Muscles / Q000294:innervation*; D011189:Potassium Chloride / Q000494:pharmacology; D012584:Sciatic Nerve / Q000502:physiology
D002110:Caffeine; D011189:Potassium Chloride; D002217:Carbachol; D000109:Acetylcholine