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ETDs are only available to UIUC Users without author permission U of I Only AAI9026237 Best, Philip M. Kwok, Wai-Meng 2011-05-07T14:13:03Z 2011-05-07T14:13:03Z 10000-01-01 1990 The ability of myofilament space calcium to modulate the sarcoplasmic reticulum (s.r.) calcium release channel in skeletal muscle was investigated. Two different experimental techniques were used to study this phenomenon. Optical techniques were used to study the effect of myoplasmic calcium concentrations on s.r. calcium release in skinned (sarcolemma removed) single muscle fibers. Results showed an inactivating and an activating effect of myoplasmic calcium on the calcium release rate. As the myoplasmic calcium concentration was increased from pCa = 7.4, calcium release rates declined to a minimum at pCa = 6.9, where release was 78 $\pm$ 3% (mean $\pm$ s.e.m.) of control (pCa = 8.4). As myoplasmic calcium was increased beyond pCa = 6.9, release rates increased. Release rates at pCa = 6.1 and 7.4 were 126 $\pm$ 11% and 100 $\pm$ 3% of control, respectively. Patch-clamp technique was used to characterize the s.r. calcium release channel. Single channel recordings of inside-out patches of extruded native s.r. membrane were made. Four distinct levels of 31 $\pm$ 3, 49 $\pm$ 2, 81 $\pm$ 2, and 128 $\pm$ 7 pS were observed (n = 9 patches) in equimolar 50 mM calcium. Multiple states were also observed under physiological conditions with calcium concentrations of pCa = 7.4, 6.9, or 6.1 in the pipette and 50 mM calcium in the bath solution. The channel was sensitive to ryanodine. At -20 mV, the addition of 1 $\mu$M ryanodine to the bath increased the open probability, P$\sb{\rm o}$, from 0.17 to 0.83. Possible modulatory effects of calcium and of phosphorylation were also investigated. When the s.r. membrane was prepared in submicromolar calcium concentrations (pCa = 7.4 and 6.9), the probability of obtaining patches with an active channel was drastically less than when the preparatory solution contained millimolar calcium. This inactivating effect of submicromolar calcium concentrations in the bath was removed by the addition of phosphatase. Made available in DSpace on 2011-05-07T14:13:03Z (GMT). No. of bitstreams: 2 license.txt: 4922 bytes, checksum: 910b249b4beec47e7ab768910c8f966f (MD5) 9026237.pdf: 4187308 bytes, checksum: cfdb644c3ca2ff2bd956aaebec4b46bb (MD5) Previous issue date: 1990 Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding (hding2@illinois.edu) on 2011-05-07T15:04:15Z Item is restricted indefinitely. Restriction data tranferred 2014-07-01T11:30:41-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: ETDs are only available to UIUC Users without author permission (UMI)AAI9026237 http://hdl.handle.net/2142/23406 eng Copyright 1990 Kwok, Wai-Meng Biophysics, General Characterization of the sarcoplasmic reticulum calcium release channel in skeletal muscle text Biophysics Biophysics University of Illinois at Urbana-Champaign Dissertation Ph.D.