Involvement of protein kinase C in muscarinic agonist-induced contractions of guinea pig real longitudinal muscle

Abstract

1. 1. Carbachol (10 −5M) caused an initial transient contraction (phasic contraction) and a subsequent late contraction (tonic contraction) in the guinea pig ileum. The phasic contraction was markedly suppressed by calmodulin antagonist W-7, but not by protein kinase C inhibitor H-7. 2. 2. The tonic contraction was suppressed by H-7, but not by W-7. 3. 3. The carbachol-induced phasic contraction in the absence of extracellular Ca 2+ was suppressed by both W-7 and H-7. 4. 4. Carbachol (10 −5M) stimulated the formation of inositol phosphates (IPs) in the guinea pig ileum. The carbacholinduced IPs formation was dependent on the extracellular Ca 2+ concentration.