title: Mechanosensitive modulation of myosin phosphorylation and phosphatidylinositol turnover in smooth muscle.
abstract: Myosin light chain phosphorylation and phosphatidylinositol turnover were measured at different muscle lengths in bovine tracheal smooth muscle. The relationship between myosin phosphorylation and muscle length was linear between optimal length (Lo) and 0.1 Lo in both unstimulated and carbachol-activated tissues. However, myosin phosphorylation in carbachol-activated tissues was more sensitive to changes in muscle length. As a result, suprabasal myosin phosphorylation induced by carbachol was significant at Lo but became insignificant at 0.1 Lo. Phosphatidylinositol turnover was assayed by measuring the formation of myo-[3H]inositol phosphates in unstimulated and carbachol-activated tissues using the Li+ method. Pairs of time-matched and length-matched muscle strips were used for control (unstimulated) and activation by carbachol. Phosphatidylinositol turnover in carbachol-activated tissues was more sensitive than that in unstimulated tissues to changing length. As a result, suprabasal phosphatidylinositol turnover induced by carbachol was significant at Lo but became insignificant at 0.1 Lo. These results indicated that myosin phosphorylation and phosphatidylinositol turnover mediated by muscarinic receptor activation were modulated by the mechanical state of smooth muscle.
authors: Division of Biology and Medicine, Brown University, Providence, Rhode Island 02912.
authors: J
authors: J
authors: Yoo
authors: R
authors: R
authors: Ellis
authors: K G
authors: KG
authors: Morgan
authors: C M
authors: CM
authors: Hai
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D002217:Carbachol / Q000494:pharmacology; D002417:Cattle; D018021:Lithium Chloride / Q000494:pharmacology; D009119:Muscle Contraction; D009130:Muscle, Smooth / Q000378:metabolism*; D009218:Myosins / Q000378:metabolism*; D010716:Phosphatidylinositols / Q000378:metabolism*; D010766:Phosphorylation; D014132:Trachea / Q000378:metabolism
chemical_list: D010716:Phosphatidylinositols; D002217:Carbachol; D009218:Myosins; D018021:Lithium Chloride; D002118:Calcium