Biomedical subjects

C L Bowman

Publications and source records attributed to C L Bowman.

21 records · Page 2Linked to original sources

PubMed1983

Kinetics of Lucifer yellow CH efflux in giant mitochondria.

The fluorescent dye Lucifer yellow CH was microinjected electrophoretically into giant mitochondria isolated from mice maintained on a diet containing cuprizone. The dye was retained by the mitochondria, indicating that it was contained in a space bounded by a selectively permeable membrane. The labelling was reversible by reversing the polarity of the current. A study of the disappearance of the fluorescence indicates that the permeability of the mitochondrial membrane to the dye (probably the lithium and/or the potassium salts) ranges from 10(-7) to 10(-8) cm/s.

Animals↗

PubMed1976

Osmotic behavior and permeability of osmotically lysed mitochondria.

Experiments were carried out with water-treated isolated rat liver mitochondria (mitochondria ghosts) previously studied by Caplan and Greenawalt (Caplan, A.I., and J.W. Greenawalt. 1966. J. Cell Biol. 31:455-472) and Vasington and Greenawalt (Vasington, F., and J. Greenawalt. 1968. J. Cell Biol. 39:661-675). The ghosts have permeability properties and osmotic behavior comparable to those of isolated mitochondria. Although they have lost most of their internal contents, they must have resealed. Four properties were found which have not been previously described in systems derived from biological membranes: (a) an osmotic behavior in the virtual absence of internal components. (b) a self-arranging property in the formation of invaginations corresponding in morphology to the cristae. The results suggest that the assembly of the molecular components of the inner membrane is sufficient to specify the morphology. Hence the surface area to volume ratio of the vesicles may specify the presence or absence of cristae-like folds. (c) an increase in the permeability of the membranes to sucrose in the presence of iso-osmotic concentrations of sucrose. (d) an independence of the light transmitted by suspensions of the vesicles from the refractive index of the external medium. This observations run counter to the general previous experience with either mitochondria or liposomes.

Animals↗

PubMedDate not supplied

Excitatory amino acids directly depolarize rat brain astrocytes in primary culture.

L-glutamic acid (L-Glu) and L-aspartic acid (L-Asp) are considered to be major excitatory amino acid transmitters, causing depolarization and excitation of neurones in the mammalian central nervous system (CNS). These responses have been thought to be an exclusively neuronal property as the excitatory amino acids either did not affect the potential of electrophysiologically unresponsive glial cells, or when an effect was seen, it was attributed to changes in external [K+] (refs 5, 6). Here we report that L-Glu directly depolarizes immunocytochemically-identified astrocytes in primary culture. L- or D-Asp and kainic acid (KA) also depolarized these cells while none or minimal changes in the resting membrane potentials were found in response to N-methyl-D-aspartate, D-glutamate, taurine, L-glutamine or to the inhibitory amino acids gamma-aminobutyric acid (GABA) and glycine. We conclude that the membrane potential of astrocytes can no longer be thought of as being responsive only to K+ and that the electrophysiological effects of excitatory amino acids in situ may not be exclusively a neuronal property.

Amino Acids↗