Characterization of the sarcoplasmic reticulum calcium release channel in skeletal muscle
Kwok, Wai-Meng
This item is only available for download by members of the University of Illinois community. Students, faculty, and staff at the U of I may log in with your NetID and password to view the item. If you are trying to access an Illinois-restricted dissertation or thesis, you can request a copy through your library's Inter-Library Loan office or purchase a copy directly from ProQuest.
Permalink
https://hdl.handle.net/2142/23406
Description
Title
Characterization of the sarcoplasmic reticulum calcium release channel in skeletal muscle
Author(s)
Kwok, Wai-Meng
Issue Date
1990
Doctoral Committee Chair(s)
Best, Philip M.
Department of Study
Biophysics
Discipline
Biophysics
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Biophysics, General
Language
eng
Abstract
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.
Use this login method if you
don't
have an
@illinois.edu
email address.
(Oops, I do have one)
IDEALS migrated to a new platform on June 23, 2022. If you created
your account prior to this date, you will have to reset your password
using the forgot-password link below.
