X irradiation of isolated sarcoplasmic reticulum vesicles

Journal Article · Sun Mar 01 04:00:00 EST 1981 · Radiat. Res.; (United States)

DOI:https://doi.org/10.2307/3575421· OSTI ID:6442881

McConnell, V; McIntosh, D B; Berman, M C

X irradiation of sarcoplasmic reticulum vesicles isolated from skeletal muscle resulted in a biphasic inactivation of Ca/sup 2 +/ transport. An initial phase of inactivation (30% of the transport activity) occurred during the irradiative period and was followed by a first-order decline in Ca/sup 2 +/ transport during the postirradiative period. The irradiative period was associated with a partial inhibition of ionophore (X-537 A)-stimulated (Ca/sup 2 +/,Mg/sup 2 +/)-ATPase activity, an increase in malonaldehyde formation, and a decrease in the total number of 5,5'-dithiobis(2-nitrobenzoate)-titratable sulfhydryl groups. These parameters were essentially unchanged during the postirradiative period. Inactivation of Ca/sup 2 +/ transport was accompanied by an increase in Ca/sup 2 +/ and to a lesser extent sucrose permeability of the membrane, Ca/sup 2 +/ bound to high-affinity sites protected against inactivation of Ca/sup 2 +/ transport but had little effect on radiation-induced changes in ATPase activity, in sulfhydryl groups or formation of malonaldehyde. Inactivation of Ca/sup 2 +/ transport is therefore largely a secondary effect, distinguishable from the chemical changes and catalytic activity on a kinetic basis and through the protection afforded by Ca/sup 2 +/. It is postulated that x irradiation uncovers a Ca/sup 2 +/ channel in the ATPase which results in enhanced Ca/sup 2 +/ permeability and cessation of vectorial Ca/sup 2 +/ transport.

• Research Organization: Univ. of Cape Town, South Africa
• OSTI ID: 6442881
• Journal Information: Radiat. Res.; (United States), Journal Name: Radiat. Res.; (United States) Vol. 85:3; ISSN RAREA
• Country of Publication: United States
• Language: English

Related Subjects

560114* -- Radiation Effects on Biochemicals-- In Animals-- (-1987)
560152 -- Radiation Effects on Animals-- Animals
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ACID ANHYDRASES
ALKALINE EARTH METALS
ANIMALS
ATP-ASE
BIOASSAY
BIOLOGICAL EFFECTS
BIOLOGICAL RADIATION EFFECTS
CALCIUM
DOSE-RESPONSE RELATIONSHIPS
ELECTROMAGNETIC RADIATION
ELEMENTS
ENZYMES
HYDROLASES
INACTIVATION
INHIBITION
IONIZING RADIATIONS
MAGNESIUM
MAMMALS
MEMBRANE TRANSPORT
MEMBRANES
METABOLISM
METALS
MUSCLES
PHOSPHOHYDROLASES
RABBITS
RADIATION EFFECTS
RADIATIONS
RADIOINDUCTION
VERTEBRATES
X RADIATION