Muscarinic-receptor stimulation enhances polyphosphoinositide breakdown in guinea-pig ileum smooth muscle.
Muscarinic-receptor stimulation by 0.1 mM-carbachol in longitudinal muscle of the guinea-pig ileum increases the incorporation of [3H]inositol into inositol-containing phospholipid. This effect was blocked by 16 microM-atropine. After 60 min incubation, carbachol increased the accumulation of total inositol phosphates 20-fold in the presence of 10 mM-Li+. Less than 20% of the total inositol phosphate corresponded to inositol 1-phosphate by ion-exchange chromatography, whereas of the remainder about two-thirds corresponded to inositol bisphosphate and one third to inositol trisphosphate. It is concluded that stimulation of muscarinic receptors in guinea-pig ileum enhances breakdown of polyphosphoinositides, suggesting that this may be a primary event associated with Ca2+ mobilization in the guinea-pig ileum.
D000818:Animals; D001285:Atropine / Q000494:pharmacology; D002217:Carbachol / Q000494:pharmacology*; D005260:Female; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007294:Inositol / Q000378:metabolism; D008094:Lithium / Q000494:pharmacology; D009130:Muscle, Smooth / Q000378:metabolism*; D018129:Phosphatidylinositol Phosphates; D010716:Phosphatidylinositols / Q000378:metabolism*; D010743:Phospholipids / Q000378:metabolism; D011976:Receptors, Muscarinic / Q000187:drug effects / Q000378:metabolism*; D013268:Stimulation, Chemical
D018129:Phosphatidylinositol Phosphates; D010716:Phosphatidylinositols; D010743:Phospholipids; D011976:Receptors, Muscarinic; D007294:Inositol; D001285:Atropine; D002217:Carbachol; D008094:Lithium