1,720,972 research outputs found
Guanylate cyclase in rod outer segments of the toad retina. Effect of light and calcium.
No full text
Characterization of ATP-dependent calcium uptake in rod outersegment disk membranes isolated from bovine retina
No full text
Structure of a protein catalyzing the formation of ll-cis retinal in the visual cycle of invertebrate eyes
No full textA1 and A2b adenosine receptors differentially modulate ATP-induced calcium responses in cultured cortical astrocytes
No full text
ATP synthesis in the disk membranes of rod outer segments of bovine retina
No full textATP is synthesized on the disk membrane isolated from rod outer segments of the bovine retina. Together with a slow component which accounted for a constant rate of about 22 nmol ATP/min/mg of protein and which was due to the adenylate kinase activity, a fast component with a maximal activity of about 58 nmol ATP/min/mg of protein was measured at physiological calcium concentrations. This fast activity disappeared in the presence of the Ca(2+) ionophore A23187, was inhibited by vanadate or thapsigargin but not by oligomycin, suggesting that this ATP synthesis is due to the reversal functioning of the Ca(2+)-ATPase previously found on the disk membranes
Sinusoidal ELF magnetic fields affect acetylcholinesterase activity in cerebellum synaptosomal membranes
No full textThe effects of extremely low frequency magnetic fields (ELF-MF) on acetylcholinesterase (AChE)
activity of synaptosomal membranes were investigated. Sinusoidal fields with 50 Hz frequency and
different amplitudes caused AChE activity to decrease about 27% with a threshold of about 0.74mT.
The decrease in enzymatic activity was independent of the time of permanence in the field and was
completely reversible. Identical results were obtained with exposure to static MF of the same
amplitudes. Moreover, the inhibitory effects on enzymatic activity are spread over frequency windows
with different maximal values at 60, 200, 350, and 475 Hz. When synaptosomal membranes were
solubilized with Triton, ELF-MF did not affect AChE activity, suggesting the crucial role of the
membrane, as well as the lipid linkage of the enzyme, in determining the conditions for inactivation.
The results are discussed in order to give an interpretation at molecular level of the macroscopic
effects produced by ELF-MF on biological systems, in particular the alterations of embryo
development in many organisms due to acetylcholine accumulation
- …
