Learn More
Ca2+ sensitivity of smooth muscle and nonmuscle myosin II reflects the ratio of activities of myosin light-chain kinase (MLCK) to myosin light-chain phosphatase (MLCP) and is a major, regulated determinant of numerous cellular processes. We conclude that the majority of phenotypes attributed to the monomeric G protein RhoA and mediated by its effector,(More)
We here review mechanisms that can regulate the activity of myosin II, in smooth muscle and non-muscle cells, by modulating the Ca2+ sensitivity of myosin regulatory light chain (RLC) phosphorylation. The major mechanism of Ca2+ sensitization of smooth muscle contraction and non-muscle cell motility is through inhibition of the smooth muscle myosin(More)
The sarcoplasmic reticulum (SR) was studied in the smooth muscles of rabbit main pulmonary artery, mesenteric vein, aorta, mesenteric artery, taenia coli, guinea pig mesenteric artery, and human uterus, and correlated with contractions of the smooth muscles in Ca-free media. SR volumes were determined in main pulmonary artery (5.1%), aorta (5%),(More)
1. Fura2 was loaded by permeation and hydrolysis of the acetoxymethyl ester into smooth muscle cells of intact thin sheets of the longitudinal layer of the small intestine of the guinea-pig, to record Ca2+ transients during contraction. 2. Cytoplasmic Ca2+ ([Ca2+]i) was monitored by computing the ratio of the fluorescence signal excited at 340 and 380 nm(More)
Approximately 60-70% of the total fiber calcium was localized in the terminal cisternae (TC) in resting frog muscle as determined by electron-probe analysis of ultrathin cryosections. During a 1.2 s tetanus, 59% (69 mmol/kg dry TC) of the calcium content of the TC was released, enough to raise total cytoplasmic calcium concentration by approximately 1 mM.(More)
Homogeneous populations of single myocytes showing good preservation of ultrastructure were obtained by enzymatic digestion of rabbit and rat hearts, and maintained in a relaxed state in the presence of free Ca2+ concentrations less than 10(-7) M. Ultrastructural details such as a cytoskeleton of 100-A filaments connected to the sarcolemma at the Z lines(More)
1. The free cytoplasmic Ca2+ concentration [( Ca2+]i) was measured in the tonic rabbit pulmonary artery and the phasic ileum smooth muscle. 2. Force development and [Ca2+]i were determined during either cumulative or non-cumulative additions of [Ca2+]o to smooth muscles depolarized with 140 mM-K+ solutions. 3. The level to which [Ca2+]i declined in(More)
The Ca2+ sensitivities of tonic (pulmonary and femoral artery) and phasic (portal vein and ileum) smooth muscles and the effects of guanosine 5'-O-(gamma-thiotriphosphate) (GTP gamma S) and norepinephrine on Ca2+ sensitivity of force development and myosin light chain (MLC20) phosphorylation were determined in permeabilized preparations that retained(More)