Subcellular Distribution of Carbonic Anhydrase and Na⁺,K⁺‐ and HCO_3‐‐ATPases in Brains of DBA and C57 Mice

Abstract

DBA/2J mice are susceptible to audiogenic seizures (ASs) in an age-dependent manner, susceptibility being maximal at 21 days of age and declining thereafter. DBA, as compared with AS-resistant C57BL/6J (C57) mice, had higher carbonic anhydrase (CA) activity in cerebral cortex, brainstem, and cerebellum homogenates at 21 days of age. CA activity was also increased in cytosolic (82%), microsomal (167%), and myelin (68%) subcellular fractions from cerebral cortex, and in cytosolic (51%) and mitochondrial (102%) fractions from brainstem of DBA mice at 21 days of age. In addition, DBA mice had a higher Na+, K+-ATPase activity in myelin from cerebral cortex, and a lower HCO3--ATPase activity in mitochondria from brainstem. The differences in CA activity in the cerebral cortex and in HCO3--ATPase were not present at 110 days of age, when DBA mice are no longer susceptible to ASs. Because CA and HCO3--ATPase are involved in maintaining a proper ionic environment for neuronal function, these data suggest that alterations in activity of these enzymes are related to the age-dependent changes in AS susceptibility in DBA mice.

Acute and Chronic Acetazolamide Administration in DBA and C57 Mice: Effects of Age

“…In all three tissues examined there was a significant increase in CA activity in DBA control mice as compared with C57 control mice. This observation is in agreement with those previously reported (Engstrom et al, 1984b). In CC, CB, and BS, there was a significant decrease in CA activity in chronically treated as compared with control DBA mice.…”

“…Cerebral cortex (CC), cerebellum (CB), and brainstem (BS) tissues were collected, cleared of meningeal tissue, and homogenized. CA activity and protein content were determined on these homogenates according to the methods of Maren (1960) and Lowry et al (1951), respectively, as previously described by Engstrom et al (1984b). CA activity and protein content were also determined on brain tissues obtained from mice of the same age of both strains that had received no ACTZ.…”

“…AGS susceptibility in DBA mice begins between 14 and 16 days, is maximal at 21 days, and is absent by 80 days of age. These studies demonstrated an increase in CA activity in brain from DBA mice as compared with C57BL/6J (C57) non-AGS susceptible mice at 21 and 110 days of age (Engstrom et al, 1984b). The role of increased CA activity is uncertain; it may be part of a neurochemical defect responsible for seizure propensity or part of a compensatory response aimed at delimiting the spread of seizure discharges.…”

Water and Electrolyte Contents, Cell pH, and Membrane Potential of Primary Cultures of Astrocytes from DBA, C57, and SW Mice

“…Uptake of 36Cl-, 22Na+, and '"Iby astrocytes (C/M) of DBA, C57, and SW mice can either enhanced or inhibited by drugs acting on specific transport systems (Table 3). It is apparent that responses of these cultured astrocytes to drugs commonly used in transport studies are very similar to those in brain and other tissues reported previously (Chow et al, 1983~1, 1987(Chow et al, 1983~1, , 1990Engstrom et al, 19846;Woodbury et al, 1984).…”

Effects of Acute and Chronic Phenytoin on the Electrolyte Content and the Activities of Na+, K+‐, Ca2+, Mg2+ ‐, and HCO3‐‐ATPases and Carbonic Anhydrase of Neonatal and Adult Rat Cerebral Cortex

“…26, NO. l , 1985 thermore, Engstrom et al (1983) have recently demonstrated that in audiogenic seizure-susceptible DBA mice, carbonic anhydrase activity in cerebral and cerebellar cortex is highest at postnatal day 21, the period when the animals are maximally susceptible to audiogenic seizures. Thus, it appears that the increased activity of these two enzymes observed in various cerebral tissues of the audiogenicsusceptible mouse are compensatory for increased levels of neuronal activity.…”