title: Protein kinase C-independent sensitization of contractile proteins to Ca2+ in alpha-toxin-permeabilized smooth muscle cells from the guinea-pig stomach.
abstract: Involvement of protein kinase C in receptor-operated Ca2+ sensitization of cell shortening was investigated by use of alpha-toxin-permeabilized smooth muscle cells from the fundus of the guinea-pig. Most of the isolated cells responded to 0.6 microM Ca2+ with a maximal shortening to approximately 65% of the resting cell length. Addition of acetylcholine (ACh) at a maximal concentration (10 microM) resulted in a marked decrease in the concentration of Ca2+ required to trigger a threshold response from 0.6 microM to 0.2 microM. The augmentation of Ca2+ sensitivity by ACh was not inhibited by specific protein kinase C inhibitors, calphostin C and K-252b at a concentration of 1 microM. These findings suggest that protein kinase C is not involved in the muscarinic receptor-operated augmentation of Ca2+ sensitivity.
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D002227:Carbazoles / Q000494:pharmacology*; D005748:Gastric Fundus; D006168:Guinea Pigs; D066298:In Vitro Techniques; D026121:Indole Alkaloids; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D009281:Naphthalenes; D011083:Polycyclic Compounds / Q000494:pharmacology*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011976:Receptors, Muscarinic / Q000378:metabolism*; D010738:Type C Phospholipases / Q000633:toxicity
chemical_list: D002227:Carbazoles; D026121:Indole Alkaloids; D009281:Naphthalenes; D011083:Polycyclic Compounds; D011976:Receptors, Muscarinic; C049985:staurosporine aglycone; D011493:Protein Kinase C; D010738:Type C Phospholipases; C058819:calphostin C; D000109:Acetylcholine; D002118:Calcium